We aimed to examine the accuracy of tumor staging of intrahepatic cholangiocarcinoma (ICC) by using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT). From January 2001 to December 2021, 202 patients underwent PET-CT, CT, and MRI for the initial staging of ICC in two institutions. Among them, 102 patients had undergone surgical treatment. Ninety patients who had a histopathological diagnosis of ICC were retrospectively reviewed. The sensitivity and specificity of 18F-FDG PET-CT, CT, and magnetic resonance imaging (MRI) in detecting tumors, satellite focus, vascular invasion, and lymph node metastases were analyzed. Ninety patients with histologically diagnosed ICC were included. PET-CT demonstrated no statistically significant advantage over CT and MR in the diagnosis of multiple tumors and macrovascular invasion, and bile duct invasion. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET-CT in lymph node metastases were 84%, 86%, 91%, 84%, and 86%, respectively. PET-CT revealed a significantly higher accuracy compared to CT or MRI (86%, 67%, and 76%, p < 0.01, respectively) in the diagnosis of regional lymph node metastases. The accuracy of tumor staging by PET-CT was higher than that by CT/MRI (PET-CT vs. CT vs. MRI: 68/90 vs. 47/90 vs. 51/90, p < 0.05). 18F-FDG PET-CT had sensitivity and specificity values for diagnosing satellite focus and vascular and bile duct invasion similar to those of CT or MRI; however, PET-CT showed higher accuracy in diagnosing regional lymph node metastases. 18F-FDG PET-CT exhibited higher tumor staging accuracy than that of CT/MRI. Thus, 18FDG PET-CT may support tumor staging in ICC.

Background: Poor subpleural perfusion (PSP) on dual-energy computed tomography (DE-CT) suggests microvasculopathy in chronic thromboembolic pulmonary hypertension (CTEPH). However, whether the microvasculopathy findings are equivalent to those in pulmonary arterial hypertension (PAH) remains unclear. The aim of this study was to elucidate the characteristics of microvasculopathy in CTEPH compared to those of that in PAH. Methods: We retrospectively reviewed subpleural perfusion on DE-CT and the hemodynamics of 23 patients with PAH and 113 with inoperable CTEPH. Subpleural perfusion on DE-CT was classified as poor (subpleural spaces in all segments with little or no perfusion) or normal. Results: PSP was observed in 51% of patients with CTEPH and in 4% of those with PAH (p < 0.01). CTEPH patients with PSP had poorer baseline hemodynamics and lower diffusing capacity for carbon monoxide divided by the alveolar volume (DLCO/VA) than those with CTEPH with normal perfusion (pulmonary vascular resistance [PVR]: 768 ± 445 dynes-sec/cm5 vs. 463 ± 284 dynes-sec/cm5, p < 0.01; DLCO/VA, 60.4 ± 16.8% vs. 75.9 ± 15.7%, p < 0.001). Despite the existence of PSP, hemodynamics improved to nearly normal in both groups after balloon pulmonary angioplasty. Conclusions: PSP on DE-CT, which is one of the specific imaging findings in CTEPH, might suggest a different mechanism of microvasculopathy from that in PAH.

The integrated positron emission tomography/magnetic resonance imaging (PET/MRI) scanner simultaneously acquires metabolic information via PET and morphological information using MRI. However, attenuation correction, which is necessary for quantitative PET evaluation, is difficult as it requires the generation of attenuation-correction maps from MRI, which has no direct relationship with the gamma-ray attenuation information. MRI-based bone tissue segmentation is potentially available for attenuation correction in relatively rigid and fixed organs such as the head and pelvis regions. However, this is challenging for the chest region because of respiratory and cardiac motions in the chest, its anatomically complicated structure, and the thin bone cortex. We propose a new method using unsupervised generative attentional networks with adaptive layer-instance normalisation for image-to-image translation (U-GAT-IT), which specialised in unpaired image transformation based on attention maps for image transformation. We added the modality-independent neighbourhood descriptor (MIND) to the loss of U-GAT-IT to guarantee anatomical consistency in the image transformation between different domains. Our proposed method obtained a synthesised computed tomography of the chest. Experimental results showed that our method outperforms current approaches. The study findings suggest the possibility of synthesising clinically acceptable computed tomography images from chest MRI with minimal changes in anatomical structures without human annotation.

OBJECTIVE: Both myocardial perfusion scintigraphy and 18F-fluorodeoxyglucose positron emission tomography (FDG PET) are useful for the diagnosis of cardiac sarcoidosis (CS). However, the association between the washout of 99mTc-labeled tracer and FDG PET has not been established. This study aimed to evaluate the association between the washout of 99mTc-labeled tracer and FDG PET findings in patients with CS. METHODS: We retrospectively analyzed 64 patients (65.0 ± 11.2 years, 53% male) with suspected CS who underwent myocardial single-photon emission computed tomography (SPECT) with 99mTc-labeled tracer and FDG PET. The SPECT images were acquired at 15 min (early images) and 3 h (delayed images) after injection and scored visually using a 17-segment model with a 5-point scoring system. The washout score was defined as the difference between the early and delayed total defect scores. FDG positivity was considered as focal or focal on diffuse patterns on visual assessment, and FDG uptake was quantified by measuring the standardized uptake value (SUV) of each of the 17 segments. RESULTS: The washout score was significantly higher for the CS group than for the non-CS group (3.0 [-1.0-5.0] vs. 0.0 [-0.5-1.0], p = 0.010). Receiver operating characteristic analysis showed that a washout score of ≥ 2 had the best accuracy for detecting CS (88% sensitivity and 56% specificity) and FDG positivity (71% sensitivity and 89% specificity). In the segment-based analysis of 833 segments from 49 patients, excluding 15 patients with diffuse FDG uptake, the median SUVs for FDG uptake for the washout scores of ≤ 0, 1, and 2 were 2.3 (1.8-3.6), 4.2 (2.9-7.8), and 8.3 (6.5-9.4), respectively (p < 0.001). CONCLUSIONS: The washout of 99mTc-labeled tracer can be a useful marker for the evaluation of FDG PET findings in patients with CS.

Background: Some of atrial fibrillation (AF) drivers are found in normal/mild late-gadolinium enhancement (LGE) areas, as well as moderate ones. The atrial wall thickness (AWT) has been reported to be important as a possible AF substrate. However, the AWT and degree of LGEs as an AF substrate has not been fully validated in humans. Objective: The purpose of this study was to evaluate the impact of the AWT in normal/mild LGE areas on AF drivers. Methods: A total of 287 segments in 15 persistent AF patients were assessed. AF drivers were defined as non-passively activated areas (NPAs), where rotational activation was frequently observed, and were detected by the novel real-time phase mapping (ExTRa Mapping), mild LGE areas were defined as areas with a volume ratio of the enhancement voxel of 0% to <10%. The AWT was defined as the minimum distance from the manually determined endocardium to the epicardial border on the LGE-MRI. Results: NPAs were found in 20 (18.0%) of 131 normal/mild LGE areas where AWT was significantly thicker than that in the passively activated areas (PAs) (2.5 ± 0.3 vs. 2.2 ± 0.3 mm, p < .001). However, NPAs were found in 41 (26.3%) of 156 moderate LGE areas where AWT was thinner than that of PAs (2.1 ± 0.2 mm vs. 2.23 ± 0.3 mm, p = .02). An ROC curve analysis yielded an optimal cutoff value of 2.2 mm for predicting the presence of an NPA in normal/mild LGE areas. Conclusion: The location of AF drivers in normal/mild LGE areas might be more accurately identified by evaluating AWT.

OBJECTIVE: Although previous studies have investigated age and gender effects on striatal subregional dopamine transporter (DaT) binding, these studies were mostly based on a conventional regions of interest-based analysis. Here, we investigated age and gender effects on striatal DaT binding at the voxel level, using a multicenter database of [ (123)I] N-omega-fluoropropyl-2beta-carbomethoxy-3beta-{4-iodophenyl}nortropane ([ (123)I] FP-CIT)-single photon emission computed tomography (SPECT) scans in 256 healthy Japanese adults. METHODS: We used the Southampton method to calculate the specific binding ratios (SBRs) of each subject's striatum and then converted the [123I] FP-CIT SPECT images to quantitative SBRs images. To investigate the effects of age and gender effects on striatal DaT binding, we performed a voxel-based analysis using statistical parametric mapping. Gender differences were also compared between young to middle-aged subjects and elderly subjects (age threshold: 60 years). RESULTS: When all subjects were explored as a group, DaT binding throughout the striatum decreased with advancing age. Among all subjects, the females showed higher DaT binding in the bilateral caudate compared to the males. In the young to middle-aged subjects, the females showed higher DaT binding throughout the striatum (with a slight caudate predominance) versus the males. In the elderly, there were no gender differences in striatal DaT binding. CONCLUSION: Our findings of striatal subregional age- and gender-related differences may provide useful information to construct a more detailed DaT database in healthy Japanese subjects.

BACKGROUND: The sigmoid septum has been generally evaluated subjectively and qualitatively, without detailed examination of its diversity, impact on the morphology of the left ventricular outflow tract (LVOT), and anatomical background. METHODS: We enrolled 100 patients without any background cardiac diseases (67.5 ± 12.8 years old; 43% women) who underwent cardiac computed tomography. Basal septal morphology was evaluated using antero-superior and medial bulging angles (bidirectional angulation of the basal septum relative to the LVOT). The eccentricity index of the LVOT, area narrowing ratio (LVOT/virtual basal ring area), aortic-to-left ventricular axial angle (angulation of the aortic root relative to the left ventricle), and wedged height (non-coronary aortic sinus to inferior epicardium distance) were also quantified. RESULTS: The antero-superior bulging, medial bulging, aortic-to-left ventricular axial angles, LVOT eccentricity index, area narrowing ratio, and wedged height were 76° ± 17°, 166° ± 27°, 127° ± 9°, 1.8 ± 0.5, 1.0 ± 0.2, and 41.2 ± 9.1 mm, respectively. Both bulging angles were correlated with each other and contributed to the narrowing and deformation of the LVOT. Angulated aortic root was not correlated with either bidirectional septal bulge or LVOT narrowing. Clockwise rotation of the aortic root rotation was an independent predictor of prominent antero-superior septal bulge. Deeper aortic wedging was a common independent predictor of bidirectional septal bulge. CONCLUSIONS: The extent of septal bulge varies in normal hearts. Along with deep aortic wedging, the bidirectional bulge of the basal septum deforms and narrows the LVOT without affecting the virtual basal ring morphology.

BACKGROUND: The impact of the extent of aortic atheroma on patients' prognosis after transcatheter aortic valve replacement (TAVR) has not been completely evaluated. This study aimed to evaluate the prognostic value of the aortic atheroma volume (AAV) derived from computed tomography, and the effect of its differences among the segments of the aorta, in patients undergoing TAVR. METHODS: In total, 143 patients with symptomatic severe aortic stenosis who underwent pre-procedural computed tomography before TAVR procedure indication were evaluated. AAV was calculated by measuring the aortic lumen and vessel volume using every 1-mm axial image and was further divided into thoracic (TAAV) and abdominal segments (AbAAV). RESULTS: During a median follow-up of 651 days, 24 all-cause and 14 cardiac deaths occurred. In the Kaplan-Meier analysis, the high AAV group had significantly higher all-cause and cardiac mortalities than the low AAV group (p = 0.016 and 0.023, respectively). Regarding segmental AAV, all-cause and cardiac mortalities did not have significant differences between the high and low TAAV groups. Moreover, all-cause and cardiac mortalities were significantly higher in the high AbAAV group than in the low AbAAV group (p = 0.0043 and 0.023, respectively). The multivariable analysis showed that only AbAAV was an independent predictor for all-cause mortality (hazard ratio: 1.06, p = 0.046). CONCLUSION: AAV was significantly associated with the mortality after TAVR. The current study suggests the pre-procedural assessment of AAV is valuable in predicting prognosis after TAVR. However, further investigation with a larger sample size is needed to validate our findings.

Background Myocardial extracellular volume fraction (ECV), measured by cardiac magnetic resonance imaging, is a useful prognostic marker for patients who have undergone aortic valve replacement (AVR) for aortic stenosis. However, the prognostic significance of ECV measurements based on computed tomography (CT) is unclear. This study evaluated the association between ECV measured with dual-energy CT and clinical outcomes in patients with aortic stenosis who underwent transcatheter or surgical AVR. Methods and Results We retrospectively enrolled 95 consecutive patients (age, 84.0±5.0 years; 75% women) with severe aortic stenosis who underwent preprocedural CT for transcatheter AVR planning. ECV was measured using iodine density images obtained by delayed enhancement dual-energy CT. The primary end point was a composite outcome of all-cause death and hospitalization for heart failure after AVR. The mean ECV measured with CT was 28.1±3.8%. During a median follow-up of 2.6 years, 22 composite outcomes were observed, including 15 all-cause deaths and 11 hospitalizations for heart failure. In Kaplan-Meier analysis, the high ECV group (≥27.8% [median value]) had significantly higher rates of composite outcomes than the low ECV group (<27.8%) (log-rank test, P=0.012). ECV was the only independent predictor of adverse outcomes on multivariable Cox regression analysis (hazards ratio, 1.25; 95% CI, 1.10‒1.41; P<0.001). Conclusions Myocardial ECV measured with dual-energy CT in patients who underwent aortic valve intervention was an independent predictor of adverse outcomes after AVR.

Detailed 3-dimensional analysis of mitral annular disjunction was undertaken in 3 comparative cases of mitral valve prolapse. A case of Barlow disease showed extensive disjunction, whereas cases of fibroelastic deficiency and forme fruste demonstrated less extensive disjunction. Considering the current controversies surrounding disjunction, these observations call for detailed research in the future. (Level of Difficulty: Advanced.).

BACKGROUND: A thorough understanding of the anatomy of the aortic valve is necessary for aortic valve-sparing surgery. Normal valvar dimensions and their relationships in the living heart, however, have yet to be fully investigated in a 3-dimensional fashion.Methods and Results:In total, 123 consecutive patients (66±12 years, Men 63%) who underwent coronary computed tomographic angiography were enrolled. Mid-diastolic morphology of the aortic roots, including height of the interleaflet triangles, geometric height, free margin length of each leaflet, effective height, and coaptation length were measured using multiplanar reconstruction images. Average height of the interleaflet triangle, geometric height, free margin length, effective height, and the coaptation length were 17.3±1.8, 14.7±1.3, 32.6±3.6, 8.6±1.4, and 3.2±0.8 mm, respectively. The right coronary aortic leaflet displayed the longest free margin length and shortest geometric height. Geometric height, free margin length, and effective height showed positive correlations with aortic root dimensions. Coaptation length, however, remained constant regardless of aortic root dimensions. CONCLUSIONS: Diversities, as well as characteristic relationships among each value involving the aortic root, were identified using living-heart datasets. The aortic leaflets demonstrated compensatory elongation along with aortic root dilatation to maintain constant coaptation length. These measurements will serve as the standard value for revealing the underlying mechanism of aortic regurgitation to plan optimal aortic valve-sparing surgery.

OBJECTIVES: This study analyzed an artificial intelligence (AI) deep learning method with a three-dimensional deep convolutional neural network (3D DCNN) in regard to diagnostic accuracy to differentiate malignant pleural mesothelioma (MPM) from benign pleural disease using FDG-PET/CT results. RESULTS: For protocol A, the area under the ROC curve (AUC)/sensitivity/specificity/accuracy values were 0.825/77.9% (81/104)/76.4% (55/72)/77.3% (136/176), while those for protocol B were 0.854/80.8% (84/104)/77.8% (56/72)/79.5% (140/176), for protocol C were 0.881/85.6% (89/104)/75.0% (54/72)/81.3% (143/176), and for protocol D were 0.896/88.5% (92/104)/73.6% (53/72)/82.4% (145/176). Protocol D showed significantly better diagnostic performance as compared to A, B, and C in ROC analysis (p = 0.031, p = 0.0020, p = 0.041, respectively). MATERIALS AND METHODS: Eight hundred seventy-five consecutive patients with histologically proven or suspected MPM, shown by history, physical examination findings, and chest CT results, who underwent FDG-PET/CT examinations between 2007 and 2017 were investigated in a retrospective manner. There were 525 patients (314 MPM, 211 benign pleural disease) in the deep learning training set, 174 (102 MPM, 72 benign pleural disease) in the validation set, and 176 (104 MPM, 72 benign pleural disease) in the test set. Using AI with PET/CT alone (protocol A), human visual reading (protocol B), a quantitative method that incorporated maximum standardized uptake value (SUVmax) (protocol C), and a combination of PET/CT, SUVmax, gender, and age (protocol D), obtained data were subjected to ROC curve analyses. CONCLUSIONS: Deep learning with 3D DCNN in combination with FDG-PET/CT imaging results as well as clinical features comprise a novel potential tool shows flexibility for differential diagnosis of MPM.

OBJECTIVES: To evaluate a deep learning model for predicting gestational age from fetal brain MRI acquired after the first trimester in comparison to biparietal diameter (BPD). MATERIALS AND METHODS: Our Institutional Review Board approved this retrospective study, and a total of 184 T2-weighted MRI acquisitions from 184 fetuses (mean gestational age: 29.4 weeks) who underwent MRI between January 2014 and June 2019 were included. The reference standard gestational age was based on the last menstruation and ultrasonography measurements in the first trimester. The deep learning model was trained with T2-weighted images from 126 training cases and 29 validation cases. The remaining 29 cases were used as test data, with fetal age estimated by both the model and BPD measurement. The relationship between the estimated gestational age and the reference standard was evaluated with Lin's concordance correlation coefficient (ρc) and a Bland-Altman plot. The ρc was assessed with McBride's definition. RESULTS: The ρc of the model prediction was substantial (ρc = 0.964), but the ρc of the BPD prediction was moderate (ρc = 0.920). Both the model and BPD predictions had greater differences from the reference standard at increasing gestational age. However, the upper limit of the model's prediction (2.45 weeks) was significantly shorter than that of BPD (5.62 weeks). CONCLUSIONS: Deep learning can accurately predict gestational age from fetal brain MR acquired after the first trimester. KEY POINTS: • The prediction of gestational age using ultrasound is accurate in the first trimester but becomes inaccurate as gestational age increases. • Deep learning can accurately predict gestational age from fetal brain MRI acquired in the second and third trimester. • Prediction of gestational age by deep learning may have benefits for prenatal care in pregnancies that are underserved during the first trimester.

AIMS: Mitral annular disjunction is fibrous separation between the attachment of the posterior mitral leaflet and the basal left ventricular myocardium initially described in dissected hearts. Currently, it is commonly evaluated by echocardiography, and potential relationships with mitral valve prolapse and ventricular arrhythmia have been suggested. However, controversy remains as its prevalence and extent have not been fully elucidated in normal living subjects. METHODS AND RESULTS: Systolic datasets of cardiac computed tomography obtained from 98 patients (mean age, 69.1 ± 12.6 years; 81% men) with structurally normal hearts were assessed retrospectively. Circumferential extent of both mitral leaflets and disjunction was determined by rotating orthogonal multiplanar reconstruction images around the central axis of the mitral valvar orifice. Distribution angle within the circumference of the mitral valvar attachment and maximal height of disjunction were quantified. In total, 96.0% of patients demonstrated disjunction. Average distribution angles of the anterior and posterior mitral leaflets were 91.3 ± 9.4° and 269.8 ± 9.7°, respectively. Average distribution angle of the disjunction was 105.1 ± 49.2°, corresponding to 39.0 ± 18.2% of the entire posterior mitral valvar attachment. Median value of the maximal height of disjunction was 3.0 (1.5-7.0) mm. Distribution prevalence map of the disjunction revealed characteristic double peaks, with frequent sites of the disjunction located at the anterior to antero-lateral and inferior to infero-septal regions. CONCLUSION: Mitral annular disjunction is a rather common finding in the normal adult heart with bimodal distribution predominantly observed involving the P1 and P3 scallops of the posterior mitral leaflet.

BACKGROUND: A computer simulation model has demonstrated that atrial fibrillation (AF) driver can be attached to heterogeneous fibrosis assessed by late gadolinium enhancement magnetic resonance imaging (LGE-MRI). However, it has not been well elucidated in patients with persistent AF. The aim of this study was to investigate whether radiofrequency (RF) applications in the fragmented LGE area (FLA) could terminate AF or convert it to atrial tachycardia (AT) and improve the rhythm outcome. METHODS: A total of 31 consecutive persistent AF patients with FLAs were enrolled (FLA ablation group, mean age: 69 ± 8 years, mean left atrial diameter: 42 ± 6 mm). A favorable response was defined as direct AF termination or AT conversion during RF applications at the FLA. The rhythm outcome was compared between the FLA ablation group and FLA burden-matched pulmonary vein isolation (PVI) group. RESULTS: Favorable responses were found in 15 (48%) of 31 patients in the FLA group (AF termination in seven, AT conversion in eight patients), but not in the PVI group. AF recurrence at 12 months follow-up was significantly less in the FLA ablation group than in the PVI group (4 [13%] vs. 12 [39%] of 31 patients, log-rank p = .023). In patients with a favorable response, AT recurred in 1 (7%) of 15 patients, but AF did not. CONCLUSIONS: FLA ablation could terminate AF or convert it to AT in half of the patients. No AF recurrence was documented in patients with a favorable response.

BACKGROUND: A computational model demonstrated that atrial fibrillation (AF) rotors could be distributed in patchy late-gadolinium enhancement (LGE) areas and play an important role in AF drivers. However, this was not validated in humans. OBJECTIVE: The purpose of this study was to evaluate the LGE properties of AF rotors in patients with persistent AF. METHODS: A total of 287 segments in 15 patients with persistent AF (long-standing persistent AF in 9 patients) that underwent AF ablation were assessed. Non-passively activated areas (NPAs), where rotational activation (AF rotor) was frequently observed, were detected by the novel real-time phase mapping (ExTRa Mapping). The properties of the LGE areas were assessed using the LGE heterogeneity and the density which was evaluated by the entropy (LGE-entropy) and the volume ratio of the enhancement voxel (LGE-volume ratio), respectively. RESULTS: NPAs were found in 61 (21%) of 287 segments and were mostly found around the pulmonary vein antrum. A receiver operating characteristic curve analysis yielded an optimal cutoff value of 5.7% and 10% for the LGE-entropy and LGE-volume ratio, respectively. The incidence of NPAs was significantly higher at segments with an LGE-entropy of >5.7 and LGE-volume ratio of >10% than at the other segments (38 [30%] of 126 vs. 23 [14%] of 161 segments; p = .001). No NPAs were found at segments with an LGE-volume ratio of >50% regardless of the LGE-entropy. Of five patients with AF recurrence, NPAs outside the PV antrum were not ablated in three patients and the remaining NPAs were ablated, but their LGE-entropy and LGE-volume ratio were low. CONCLUSION: AF rotors are mostly distributed in relatively weak and much more heterogenous LGE areas.

PURPOSE: To retrospectively assess the repeatability of physiological F-18 labeled fluorodeoxyglucose (FDG) uptake in the skin on positron emission tomography/magnetic resonance imaging (PET/MRI) and explore its regional distribution and relationship with sex and age. METHODS: Out of 562 examinations with normal FDG distribution on whole-body PET/MRI, 74 repeated examinations were evaluated to assess the repeatability and regional distribution of physiological skin uptake. Furthermore, 224 examinations were evaluated to compare differences in the uptake due to sex and age. Skin segmentation on PET was performed as body-surface contouring on an MR-based attenuation correction map using an off-line reconstruction software. Bland-Altman plots were created for the repeatability assessment. Kruskal-Wallis test was performed to compare the maximum standardized uptake value (SUVmax) with regional distribution, age, and sex. RESULTS: The limits of agreement for the difference in SUVmean and SUVmax of the skin were less than 30%. The highest SUVmax was observed in the face (3.09±1.04), followed by the scalp (2.07±0.53). The SUVmax in the face of boys aged 0-9 years and 10-20 years (1.33±0.64 and 2.05±1.00, respectively) and girls aged 0-9 years (0.98±0.38) was significantly lower than that of men aged ≥20 years and girls aged ≥10 years (p<0.001). In women, the SUVmax of the face (2.31±0.71) of ≥70-year-olds was significantly lower than that of 30-39-year-olds (3.83±0.82) (p<0.05). CONCLUSION: PET/MRI enabled the quantitative analysis of skin FDG uptake with repeatability. The degree of physiological FDG uptake in the skin was the highest in the face and varied between sexes. Although attention to differences in body habitus between age groups is needed, skin FDG uptake also depended on age.

We hypothesized that, in discrimination between benign and malignant parotid gland tumors, high diagnostic accuracy could be obtained with a small amount of imbalanced data when anomaly detection (AD) was combined with deep leaning (DL) model and the L2-constrained softmax loss. The purpose of this study was to evaluate whether the proposed method was more accurate than other commonly used DL or AD methods. Magnetic resonance (MR) images of 245 parotid tumors (22.5% malignant) were retrospectively collected. We evaluated the diagnostic accuracy of the proposed method (VGG16-based DL and AD) and that of classification models using conventional DL and AD methods. A radiologist also evaluated the MR images. ROC and precision-recall (PR) analyses were performed, and the area under the curve (AUC) was calculated. In terms of diagnostic performance, the VGG16-based model with the L2-constrained softmax loss and AD (local outlier factor) outperformed conventional DL and AD methods and a radiologist (ROC-AUC = 0.86 and PR-ROC = 0.77). The proposed method could discriminate between benign and malignant parotid tumors in MR images even when only a small amount of data with imbalanced distribution is available.

To investigate the feasibility of pre-procedural morphological assessment of coronary artery calcification in severely calcified lesions with electrocardiography (ECG)-gated non-contrast computed tomography (CT). Severely calcified coronary arteries in patients who underwent ECG-gated non-contrast CT prior to optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) were studied retrospectively. CT and OCT data were co-registered by marking landmark structures such as side branches and reviewed side by side with cross-sectional images. The maximum calcium angle (MCA) and presence of nodular calcification (NC) were evaluated. A total of 496 cross-sections in 16 lesions were included in this analysis. The Pearson correlation coefficient between CT- and OCT-derived MCA was 0.92 (p < 0.001). Bland-Altman plots of OCT-derived MCA in relation to CT-derived MCA showed a mean bias of 4.8 degrees with 95% limits of agreement of - 69.7 to 79.4 degrees. Sensitivity, specificity, and positive and negative predictive values of CT in identifying MCA > 270 degrees were 90.3%, 79.7%, 92.1%, and 97.4%, respectively. Sensitivity, specificity, and positive and negative predictive values of CT in identifying NC were 73.3%, 97.5%, 47.8%, and 99.2%, respectively. ECG-gated non-contrast coronary CT might be helpful to obtain detailed information of severe coronary artery calcification before PCI.

INTRODUCTION: Very few studies have been performed to evaluate both the severity and site of aortic calcification (AC) in both end-stage kidney disease (ESKD) and diabetes mellitus (DM). The purpose of our study was to examine the utility of a newly developed three-dimensional (3D) visualization and quantification method compared with other methods to evaluate vascular calcification in ESKD patients with and without DM. MATERIALS AND METHODS: Fifty patients with ESKD before initiating hemodialysis at our hospital were included in the present study. They were divided into the two groups, depending on the presence or absence of DM: Control group (n = 31) and DM group (n = 19). The volume and site of AC were evaluated via computed tomography (CT) scan using a 3D visualization and quantification method. RESULTS: Total calcification volume was significantly greater in the DM group than in the Control group. Calcification volume in the descending and abdominal aortas was greater in the DM group compared to the Control group. There were no significant differences in calcification volume in the aortic root, ascending aorta, and aortic arch. Calcification volume of the whole aorta, the descending aorta, and the abdominal aorta were each significantly correlated with age, diastolic blood pressure and pulse pressure. CONCLUSION: This study using a 3D visualization and quantification method demonstrated that AC was more severe and occurred more frequently in the abdominal aorta in ESKD patients with DM compared to those without DM. This method would enable us to precisely evaluate the volume and distribution of AC.

The usefulness of sparse-sampling CT with deep learning-based reconstruction for detection of metastasis of malignant ovarian tumors was evaluated. We obtained contrast-enhanced CT images (n = 141) of ovarian cancers from a public database, whose images were randomly divided into 71 training, 20 validation, and 50 test cases. Sparse-sampling CT images were calculated slice-by-slice by software simulation. Two deep-learning models for deep learning-based reconstruction were evaluated: Residual Encoder-Decoder Convolutional Neural Network (RED-CNN) and deeper U-net. For 50 test cases, we evaluated the peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) as quantitative measures. Two radiologists independently performed a qualitative evaluation for the following points: entire CT image quality; visibility of the iliac artery; and visibility of peritoneal dissemination, liver metastasis, and lymph node metastasis. Wilcoxon signed-rank test and McNemar test were used to compare image quality and metastasis detectability between the two models, respectively. The mean PSNR and SSIM performed better with deeper U-net over RED-CNN. For all items of the visual evaluation, deeper U-net scored significantly better than RED-CNN. The metastasis detectability with deeper U-net was more than 95%. Sparse-sampling CT with deep learning-based reconstruction proved useful in detecting metastasis of malignant ovarian tumors and might contribute to reducing overall CT-radiation exposure.

In the original publication of this article [1] the wording of '3Di-PMR' was different between the text and figures.

BACKGROUND: The left ventricular apex commonly has a paper-thin structure. However, available data about its structure are limited to variable samples, methodologies, and results. OBJECTIVE: To investigate the structural anatomy of the left ventricular apex using living heart datasets with the latest computed tomography scanner. METHODS: One hundred thirty-one consecutive patients (median age, 73 years; 58% men) who underwent cardiac computed tomography were retrospectively analyzed. Patients with severe aortic stenosis were analyzed separately. Thickness and diameters of the thinnest part of the left ventricular apex during mid-diastole were measured using orthogonal multiplanar reconstruction images. The area of thinning was estimated using the formula for the ellipse. RESULTS: In 88 patients without severe aortic stenosis, the median thickness of the thinnest area of the left ventricular apex was only 0.9 mm. Among them, 74%, 99%, and 100% of cases displayed a left ventricular apex thinner than 1.0, 3.0, and 5.0 mm, respectively. The median area of the thinnest region was 5.6 mm2 . In 43 patients with severe aortic stenosis, the median thickness of the thinnest area of the left ventricular apex was 1.2 mm. Among them, 51%, 93%, and 100% of cases displayed a left ventricular apex thinner than 1.0, 3.0, and 5.0 mm, respectively. The median area of the thinnest region was 3.9 mm2 . CONCLUSIONS: Localized thinning of the left ventricular apex is unexceptional, regardless of aortic stenosis with concentric left ventricular hypertrophy, thus highlighting the need for a reappreciation of this feature to avoid inadvertent catastrophic complications.

BACKGROUND: Periprocedural myocardial injury (pMI) is a common complication of elective percutaneous coronary intervention (PCI) that reduces some of the beneficial effects of coronary revascularization and impacts the risk of cardiovascular events. We developed a 3-dimensional volumetric cardiovascular magnetic resonance (CMR) method to evaluate coronary high intensity plaques and investigated their association with pMI after elective PCI. METHODS: Between October 2012 and October 2016, 141 patients with stable coronary artery disease underwent T1-weighted CMR imaging before PCI. A conventional 2-dimensional CMR plaque-to-myocardial signal intensity ratio (2D-PMR) and the newly developed 3-dimensional integral of PMR (3Di-PMR) were measured. 3Di-PMR was determined as the sum of PMRs above a threshold of > 1.0 for voxels in a target plaque. pMI was defined as high-sensitivity cardiac troponin T > 0.07 ng/mL. RESULTS: pMI following PCI was observed in 46 patients (33%). 3Di-PMR was significantly higher in patients with pMI than those without pMI. The optimal 3Di-PMR cutoff value for predicting pMI was 51 PMR*mm3 and the area under the receiver operating characteristic curve (0.753) was significantly greater than that for 2D-PMR (0.683, P = 0.015). 3Di-PMR was positively correlated with lipid volume (r = 0.449, P < 0.001) based on intravascular ultrasound. Stepwise multivariable analysis showed that 3Di-PMR ≥ 51 PMR*mm3 and the presence of a side branch at the PCI target lesion site were significant predictors of pMI (odds ratio [OR], 11.9; 95% confidence interval [CI], 4.6-30.4, P < 0.001; and OR, 4.14; 95% CI, 1.6-11.1, P = 0.005, respectively). CONCLUSIONS: 3Di-PMR coronary assessment facilitates risk stratification for pMI after elective PCI. TRIAL REGISTRATION: retrospectively registered.

AIMS: To investigate the clinical impact of T1 mapping for detecting myocardial impairment in takotsubo cardiomyopathy (TTC) over time. METHODS AND RESULTS: In 23 patients with the apical ballooning type of TTC, the following 3T magnetic resonance (MR) examinations were performed at baseline and 3 months after TTC onset: T2-weighted imaging, T2 mapping, native T1 mapping, extracellular volume fraction (ECV), and late gadolinium enhancement. Eight healthy controls underwent the same MR examinations. Serial echocardiography was performed daily for ≥7 days and monthly until 3 months after onset. The median time from onset to MR examination was 7 days. During the acute phase, patients had, relative to controls, higher native T1 (1438 ± 162 vs. 1251 ± 90 ms, P < 0.001), ECV (35 ± 5% vs. 29 ± 4%, P < 0.001), and T2 (90 ± 34 vs. 68 ± 12 ms, P < 0.001) for the entire heart. Per-region analysis showed that higher native T1 and T2 in the basal region were correlated with lower left ventricular ejection fraction (r = -0.599, P = 0.004 and r = -0.598, P = 0.003, respectively). Receiver operator characteristic analysis showed that the area under the curve for native T1 (0.96) was significantly larger than that for T2 (0.86; P = 0.005) but similar to that for ECV (0.92; P = 0.104). At 3-month follow-up, native T1, ECV, and T2 in the apical region remained significantly elevated in all patients with TTC. The number of left ventricular (LV) segments with elevated native T1 (cut-off value 1339 ms) was significantly correlated with prolonged LV wall motion recovery time (r = 0.494, P = 0.027). CONCLUSION: Characterization of myocardium with native T1 mapping is a promising method for predicting LV wall motion restoration in TTC.

BACKGROUND: Because endovascular abdominal aortic repair (EVAR) lowers the lumbar arterial blood flow, we hypothesized that the volume of the psoas muscle decreases after surgery. When internal iliac artery (IIA) embolization is performed, the lumbar arterial blood flow further decreases; therefore, we also hypothesized that the decrease in the volume of the psoas muscle becomes more significant. This study was performed to assess the volume change in the psoas muscle after EVAR. METHODS: Fifty-three consecutive patients who underwent EVAR from January 2016 to December 2016 were included. The psoas muscle volume was measured by preoperative and postoperative computed tomography (CT). Postoperative CT scans were performed 6-12 months after EVAR. Axial CT images with a 2-mm slice thickness were used to measure the psoas muscle volume. Data were transferred to a 3-dimensional workstation, and the psoas muscle volume was measured. RESULTS: In the EVAR group, the volume of the psoas muscle decreased by an average of 5.8 mL (4.6%) from 114.8 ± 32.0 mL preoperatively to 109.0 ± 30.3 mL postoperatively (P < 0.01). There was a significant difference in the change in the psoas muscle volume between patients with and without IIA embolization (embolization group: preoperative 118.1 ± 31.0 mL, postoperative 107.5 ± 29.2 mL, mean volume change rate -8.8%; nonembolization group: preoperative 114.0 ± 32.3 mL, postoperative 109.4 ± 30.7 mL, mean volume change rate -3.6%; P < 0.05). CONCLUSIONS: The psoas muscle volume is reduced with EVAR. Moreover, when the IIA is embolized, the psoas muscle volume is further reduced.

PURPOSE: The reliability of assessment of the artery of Adamkiewicz before the aortic repair is highly dependent on the display of the continuity of this artery with the aorta, mainly around the vertebral pedicle, by computed tomography angiography (CTA). We hypothesized that the sharp filter kernel can improve visualization of this continuity of the vessel structure because of its edge enhancement and high-spatial resolution. This study was performed to compare the subjective and objective image quality of spinal CTA reconstructed with sharp and smooth filter kernels. METHODS: We retrospectively reviewed 40 consecutive patients who had undergone 80-kV CTA to detect the artery of Adamkiewicz before aortic repair. We measured the CT number and the contrast-to-noise ratio of the anterior spinal artery to the spinal cord. Furthermore, the continuity of the artery of Adamkiewicz was evaluated using a 3-point scale (2 points, absolute; 0 points, undetectable). RESULTS: CTA with the sharp filter kernel showed a significantly higher CT number and contrast-to-noise ratio of the spinal artery than did CTA with the smooth filter kernel (P < .001 for both). Moreover, the sharp filter kernel showed a significantly higher continuity of the artery of Adamkiewicz with the aorta than did the smooth filter kernel (P < .001). CONCLUSIONS: The sharp filter kernel significantly improved the image quality in low-tube-voltage CTA for the assessment of the artery of Adamkiewicz. Thus, CTA with the sharp filter kernel can generate a high-confidence level in the evaluation of the artery of Adamkiewicz.

PURPOSE: The aim of this multicenter trial was to generate a [123I]FP-CIT SPECT database of healthy controls from the common SPECT systems available in Japan. METHODS: This study included 510 sets of SPECT data from 256 healthy controls (116 men and 140 women; age range, 30-83 years) acquired from eight different centers. Images were reconstructed without attenuation or scatter correction (NOACNOSC), with only attenuation correction using the Chang method (ChangACNOSC) or X-ray CT (CTACNOSC), and with both scatter and attenuation correction using the Chang method (ChangACSC) or X-ray CT (CTACSC). These SPECT images were analyzed using the Southampton method. The outcome measure was the specific binding ratio (SBR) in the striatum. These striatal SBRs were calibrated from prior experiments using a striatal phantom. RESULTS: The original SBRs gradually decreased in the order of ChangACSC, CTACSC, ChangACNOSC, CTACNOSC, and NOACNOSC. The SBRs for NOACNOSC were 46% lower than those for ChangACSC. In contrast, the calibrated SBRs were almost equal under no scatter correction (NOSC) conditions. A significant effect of age was found, with an SBR decline rate of 6.3% per decade. In the 30-39 age group, SBRs were 12.2% higher in women than in men, but this increase declined with age and was absent in the 70-79 age group. CONCLUSIONS: This study provided a large-scale quantitative database of [123I]FP-CIT SPECT scans from different scanners in healthy controls across a wide age range and with balanced sex representation. The phantom calibration effectively harmonizes SPECT data from different SPECT systems under NOSC conditions. The data collected in this study may serve as a reference database.

It is known that calcium-containing phosphate binders are more closely associated with the progression of vascular calcification than non-calcium-containing phosphate binders. In this study, we investigated the effect of the non-calcium-containing phosphate binder, lanthanum carbonate on the progression of coronary artery calcification and cardiovascular abnormalities compared to that of calcium-containing phosphate binder in chronic kidney disease patients during the early period after initiating hemodialysis. This was a randomized open-label study in which patients were divided into the calcium carbonate or lanthanum carbonate group. We evaluated blood samples, coronary artery calcification using high-resolution computed tomography, and cardiac abnormalities using echocardiography prior to and after initiating hemodialysis. Cardiac dimension and systolic function were significantly improved in the lanthanum carbonate group compared to those in the calcium carbonate group. Although statistically significant differences were not observed in all the patients, only among patients with moderate coronary artery calcification, the changes in coronary artery calcification score at 18 months were significantly smaller in the lanthanum carbonate group than those in the calcium carbonate group. The percent change in coronary artery calcification at 18 months was significantly correlated with the serum fibroblast growth factor 23 levels at 18 months (r = 0.245, P <  0.05). This significant correlation was particularly strong in patients with moderate coronary artery calcification (r = 0.593, P <  0.001). Our study suggests that lanthanum carbonate ameliorates cardiac abnormalities, and may slow coronary artery calcification development in patients with moderate coronary artery calcification, during the early period following hemodialysis initiation.

BACKGROUND AND PURPOSE: Preprocedural identification of the Adamkiewicz artery is crucial in patients with aortic diseases. This study aimed to compare 70-kV CTA with conventional 120-kV CTA for the identification of the Adamkiewicz artery, examining differences in radiation dose and image quality. MATERIALS AND METHODS: We retrospectively analyzed 2 equal groups of 60 patients who had undergone 70-kV or 120-kV CTA to detect the Adamkiewicz artery before aortic repair. Size-specific dose estimate, the CT number of the aorta, and the contrast-to-noise ratio of the anterior spinal artery to the spinal cord were recorded. Furthermore, detectability of the Adamkiewicz artery was evaluated by using a 4-point continuity score (3, definite to 0, undetectable). RESULTS: There was significantly lower radiation exposure with 70-kV CTA than 120-kV CTA (median size-specific dose estimate, 23.1 versus 61.3 mGy, respectively; P < .001). CT number and contrast-to-noise ratio were both significantly higher in the 70-kV CTA group than the 120-kV group (999.1 HU compared with 508.7 HU, and 5.6 compared with 3.4, respectively; P < .001 for both). Detectability of the Adamkiewicz artery was not impaired in the 70-kV CTA group (90.0% versus 83.3% in the 120-kV group, P = .28). Moreover, the Adamkiewicz artery was detected with greater confidence with 70-kV CTA, reflected by a significantly superior continuity score (median, 3) compared with 120-kV CTA (median, 2; P = .001). CONCLUSIONS: Seventy-kilovolt CTA has substantial advantages for the identification of the Adamkiewicz artery before aortic repair, with a significantly lower radiation exposure and superior image quality than 120-kV CTA.

© 2017 IEEE. This paper proposes an automated method to track the tag intersections in the Tagged Magnetic Resonance Image (MRI) to diagnose Heart failure. Heart Failure brings about declining of a function to supply blood by contraction of myocardium. Physician always analyzes myocardial motion using the images. The proposed method employs Mean shift belief propagation (MSBP) that integrates all information about image to track tag intersections. This method enables us to extract tag intersections with disappearing tags over time. The experimental results show a clinical ability of tracking tag intersections.

Coronary artery calcification (CAC), cardiac valve calcification (CVC) and left ventricular hypertrophy (LVH) are frequently observed in chronic kidney disease (CKD) patients. These abnormalities significantly affect morbidity and mortality. The aim of this study was to investigate the relationship between CAC, CVC and LVH in CKD patients. This study included 96 patients who were hospitalized and initiated hemodialysis between December 2011 and July 2014 at our five institutions. Multi-detector computed tomography for the quantification of CAC using the Agatston score and transthoracic echocardiography for assessing CVC and LVH were performed for all patients included in the study. We semi-quantitatively evaluated the severity of CVC as a valvular calcification score. We also assessed the presence of LVH in patients with CAC and/or CVC. Among the 96 patients, the prevalence of CAC was 81.3% and CVC was 65.0%. The severity of CAC was closely and significantly associated with that of CVC. The percentage of patients with LVH was the greatest in those with both severe CAC and CVC. CAC was significantly more severe in patients with concentric hypertrophy compared to those with normal geometry. At the initiation of hemodialysis, most CKD patients had CAC, CVC and LVH. In addition, cardiac calcification was significantly associated with LVH in these patients.

The objective of the present study was the determination of the potential dosimetric benefits of using metal-artefact-suppressed dual-energy computed tomography (DECT) images for cases involving pedicle screw implants in spinal sites. A heterogeneous spinal phantom was designed for the investigation of the dosimetric effect of the pedicle-screw-related artefacts. The dosimetric comparisons were first performed using a conventional two-directional opposed (AP-PA) plan, and then a volumetric modulated arc therapy (VMAT) plan, which are both used for the treatment of spinal metastases in our institution. The results of Acuros (R) XB dose-to-medium (Dm) and dose-to-water (Dw) calculations using different imaging options were compared with experimental measurements including the chamber and film dosimetries in the spinal phantom. A dual-energy composition image with a weight factor of -0.2 and a dual-energy monochromatic image (DEMI) with an energy level of 180 keV were found to have superior abilities for artefact suppression. The Dm calculations revealed greater dosimetric effects of the pedicle screwrelated artefacts compared to the Dw calculations. The results of conventional single-energy computed tomography showed that, although the pedicle screws were made from low-Z titanium alloy, the metal artefacts still have dosimetric effects, namely, an average (maximum) Dm error of 4.4% (5.6%) inside the spinal cord for a complex VMAT treatment plan. Our findings indicate that metal-artefact suppression using the proposed DECT (DEMI) approach is promising for improving the dosimetric accuracy near the implants and inside the spinal cord (average (maximum) Dm error of 1.1% (2.0%)).

OBJECTIVES The aim of this study was to investigate the individual and combined accuracy of dynamic computed tomography (CT) myocardial perfusion imaging (MPI) and computed tomography angiography (CTA) fractional flow reserve (FFR) for the identification of functionally relevant coronary artery disease (CAD). BACKGROUND Coronary CTA has become an established diagnostic test for ruling out CAD, but it does not allow interpretation of the hemodynamic severity of stenotic lesions. Two recently introduced functional CT techniques are dynamic MPI and CTA FFR using computational fluid dynamics. METHODS From 2 institutions, 74 patients (n - 62 men, mean age 61 years) planned for invasive angiography with invasive FFR measurement in 142 vessels underwent CTA imaging and dynamic CT MPI during adenosine vasodilation. A patient-specific myocardial blood flow index was calculated, normalized to remote myocardial global left ventricular blood flow. CTA FFR was computed using an on-site, clinician-operated application. Using binary regression, a single functional CT variable was created combining both CT MPI and CTA FFR. Finally, stepwise diagnostic work-up of CTA FFR with selective use of CT MPI was simulated. The diagnostic performance of CT MPI, CTA FFR, and CT MPI integrated with CTA FFR was evaluated using C statistics with invasive FFR, with a threshold of 0.80 as a reference. RESULTS Sensitivity, specificity, and accuracy were 73% (95% confidence interval [CI]: 61% to 86%), 68% (95% CI: 56% to 80%), and 70% (95% CI: 62% to 79%) for CT MPI and 82% (95% CI: 72% to 92%), 60% (95% CI: 48% to 72%), and 70% (63% to 80%) for CTA FFR. For CT MPI integrated with CTA FFR, diagnostic accuracy was 79% (95% CI: 71% to 87%), with improvement of the area under the curve from 0.78 to 0.85 (p < 0.05). Accuracy of the stepwise approach was 77%. CONCLUSIONS CT MPI and CTA FFR both identify functionally significant CAD, with comparable accuracy. Diagnostic performance can be improved by combining the techniques. A stepwise approach, reserving CT MPI for intermediate CTA FFR results, also improves diagnostic performance while omitting nearly one-half of the population from CT MPI examinations. (C) 2017 by the American College of Cardiology Foundation. Published by Elsevier. All rights reserved.

The aortic root is wedged within the cardiac base. The precise extent of aortic wedging, however, and its influence on the surrounding cardiac structures, has not been systematically investigated. We analysed 100 consecutive patients, who underwent coronary arterial computed tomographic angiography. We assessed the extent of aortic wedging by measuring the vertical distance between the non-adjacent aortic sinus and the inferior epicardium. A shorter distance indicates deeper aortic wedging. We assessed the tilt angle and diameter of the ascending aorta, the relative heights of the left atrial roof and the oval fossa, the shape of the proximal right coronary artery, the angle of the aorta relative to the left ventricular axis, and the lung volume. The mean extent of wedging was 42.7 +/- 9.8mm. Multivariate analysis revealed that ageing, male gender, increased body mass index, patients without cardiomyopathy, the extent of tilting and dilation of the ascending aorta, and lung volume were all independent predictors for deeper aortic wedging (R-2=0.7400, P<0.0001). The extent of wedging was additionally correlated with a relatively high left atrial roof (R-2=0.1394, P<0.0001) and oval fossa (R-2=0.1713, P<0.0001), the shepherd's crook shape of the proximal right coronary artery (R-2=0.2376, P<0.0001), and the narrowness of the angulation of the root relative to the left ventricular axis (R-2=0.2544, P<0.0001). In conclusion, ageing, male gender, obesity, background cardiac disease, aortic tilting and dilation, and lung volume are all correlated with the extent of wedging of the aortic root within the cardiac base.

To investigate the additional value of transmural perfusion ratio (TPR) in dynamic CT myocardial perfusion imaging for detection of haemodynamically significant coronary artery disease compared with fractional flow reserve (FFR). Subjects with suspected or known coronary artery disease were prospectively included and underwent a CT-MPI examination. From the CT-MPI time-point data absolute myocardial blood flow (MBF) values were temporally resolved using a hybrid deconvolution model. An absolute MBF value was measured in the suspected perfusion defect. TPR was defined as the ratio between the subendocardial and subepicardial MBF. TPR and MBF results were compared with invasive FFR using a threshold of 0.80. Forty-three patients and 94 territories were analysed. The area under the receiver operator curve was larger for MBF (0.78) compared with TPR (0.65, P = 0.026). No significant differences were found in diagnostic classification between MBF and TPR with a territory-based accuracy of 77 % (67-86 %) for MBF compared with 70 % (60-81 %) for TPR. Combined MBF and TPR classification did not improve the diagnostic classification. Dynamic CT-MPI-based transmural perfusion ratio predicts haemodynamically significant coronary artery disease. However, diagnostic performance of dynamic CT-MPI-derived TPR is inferior to quantified MBF and has limited incremental value. aEuro cent The transmural perfusion ratio from dynamic CT-MPI predicts functional obstructive coronary artery disease aEuro cent Performance of the transmural perfusion ratio is inferior to quantified myocardial blood flow aEuro cent The incremental value of the transmural perfusion ratio is limited.

The location of the heart within the thorax varies significantly between individuals. The resultant diversity of the anatomical cardiac long axis, however, and its determinants, have yet to be systematically investigated. We enrolled 100 consecutive patients undergoing coronary arterial computed tomographic angiography, decomposing the vector of the anatomical cardiac long axis by projecting it to horizontal, frontal, and sagittal planes. The projected vectors on each plane were then converted into three rotation angles using coordinate transformation. We then measured the extent of aortic wedging, using the vertical distance between the inferior margins of the non-adjacent aortic sinus and the epicardium. We took the aortic root rotation angle to be zero when an "en face" view of the right coronary aortic sinus was obtained in the frontal view, defining leftward rotation to be positive. The mean horizontal, frontal, and sagittal rotation angles were 48.7 degrees +/- 9.5 degrees, 52.3 degrees +/- 12.0 degrees, and 34.0 degrees +/- 11.2 degrees, respectively. The mean extent of aortic wedging, and the aortic root rotation angle, were 42.7 +/- 9.8 mm, and 5.3 degrees +/- 16.4 degrees. Horizontal rotation of the anatomical axis was associated with leftward and ventral rotation, and vice versa. Multivariate analysis showed aortic root rotation to be associated with horizontal cardiac rotation, while aortic wedging is associated with frontal and sagittal cardiac rotation. We have quantified the marked individual variation observed in the anatomical axis of the living heart, identifying the different mechanisms involved in producing the marked three-dimensional diversity of the living heart. (C) 2017 Wiley Periodicals, Inc.

Objectives: To achieve the efficient usage of contrast material (CM) in high-pitch CT aortography, an appropriate duration of the CM injection is crucial. We used a modification of the double-level test bolus method for determination of proper injection duration with the aim of evaluating the image quality of tailored-duration CM injection compared with that of a fixed duration. Materials and Methods: The institutional review board approved retrospective review of 80 consecutive subjects who had undergone high-pitch 70-kVp CT aortography with a modified double-level test bolus method. The interval between peak enhancement at the aortic root and femoral artery was derived from the time/attenuation curves. A total of 40 subjects underwent CT aortography with individually set duration time from the results. The remaining subjects underwent CT aortography with a fixed-duration time. The density values at several parts of the aorta were assessed. The differences in image quality and CM amount used for each method were assessed by Welch test. Results: The injection duration was almost 50% shorter (median, 15 seconds; range, 11-25 seconds) when individually tailored. The mean CM amount was reduced by 50% (46.2-23.9 mL, P < 0.01). The range of mean CT attenuation throughout the aorta was not significantly different between the 2 methods (316-327 HU and 305-321 HU, P > 0.05, respectively). Conclusions: The modified double-level test bolus method in high-pitch CT aortography can significantly reduce the amount of CM without adversely affecting image quality.

Background: It is axiomatic that the diameter of the virtual basal ring of the aortic root, which is elliptical rather than circular, will differ when assessed using between bisecting as opposed to off--center cuts. Such differences, however, which pertain directly to echocardiographic assessments of the so-called valvar annulus, have yet to be systematically explored. Methods: We retrospectively analyzed 30 patients undergoing coronary computed tomographic angiography, measuring the virtual basal ring diameter using routine multiplanar reconstructions. We made orthogonal bisecting cuts from the nadir of the hinge of the right coronary aortic leaflet to the center of the opposite inter-leaflet fibrous triangle between the noncoronary and left coronary aortic leaflets. We compared these measurements with orthogonal off-center cuts made through the nadirs of the hinges of the adjacent leaflets. Results: The measured diameter of the virtual basal ring was significantly longer when measured using the bisecting cut as opposed to all off-center cuts (mean difference: 1.35 +/- 1.34 mm, P<.0001; 0.77 +/- 0.95 mm, P=.0001, respectively). The measured diameters of the sinuses of Valsalva, in contrast, were significantly shorter when measured using the bisecting cut (mean difference: 3.24 +/- 1.38 mm, P<.0001; N 2.86 +/- 1.61 mm, P<.0001). Conclusions: There are significant differences in the diameters of the aortic root, which represent the echocardiographic annulus, when measured using bisecting as opposed to off-center cuts. Account should be taken of these differences when using cross-sectional echocardiographic measurements to assess the dimensions of the aortic root.

Late-onset amyloidogenic transthyretin (ATTR) type familial amyloid polyneuropathy (FAP) shows features distinct from those of early-onset hereditary ATTR type FAP. We herein describe an asymptomatic 68-year-old man with late-onset ATTR type FAP whose serial annual electrocardiograms demonstrated progressive left bundle branch block. Latent but severe cardiac involvement seems to be one feature of late-onset ATTR type FAP, similar to senile systemic amyloidosis (SSA). Early differential diagnosis of late-onset ATTR type FAP from SSA is important because, currently, only the former has new therapeutic options available in Japan. The present case report, therefore, highlights the necessity of careful observation for periodic electrocardiograms.

BackgroundRoof-dependent atrial tachycardia (roof AT) sometimes occurs after pulmonary vein isolation (PVI) of atrial fibrillation (AF). This study aimed to investigate the relationship between the anatomy of the residual left atrial posterior wall and occurrence of roof AT. MethodsA total of 265 patients with AF who underwent PVI were enrolled. After the PVI, induced or recurrent roof AT was confirmed by an entrainment maneuver or activation mapping using a three-dimensional (3D) mapping system. To identify the predictors of roof AT, the minimum distance between both PVI lines (d-PVI) was measured by a 3D mapping system and the anatomical parameters, including the left atrial (LA) diameter, left atrial volume index (LAVi), and shape of the left atrial roof, were analyzed by 3D computed tomography. ResultsRoof AT was documented in 11 (4.2%) of 265 patients. A multivariable analysis demonstrated that the d-PVI, Deep V shape of the LA roof, and LAVi were associated with roof AT occurrences (d-PVI: odds ratio: 0.72, confidence interval [CI]: 0.61-0.86, P < 0.001; Deep V shape: odds ratio: 0.19, CI: 0.04-0.82, P = 0.03; LAVi: odds ratio: 1.05, CI: 1.02-1.07, P = 0.001). A receiver-operating characteristic curve analysis yielded an optimal cut-off value of 15.5 mm and 55.7 mL/m(2) for the d-PVI and LAVi, respectively. ConclusionThe shorter d-PVI at the LA roof, greater LAVi, and Deep V shape were associated with the occurrence of a roof AT.

Background: A high serum phosphate level is a well-known risk factor for vascular calcification (VC) in patients on hemodialysis (HD). However, the association between the serum phosphate level and VC in non-HD patients is unclear. Our aim was to assess the impact of serum phosphate level on aortic calcification (AC) volume in non-HD patients undergoing cardiovascular surgery. Methods: A total of 117 patients who underwent thoracoabdominal computed tomography as a preoperative general evaluation before cardiovascular surgery were enrolled. The total AC volume was quantified using the volume-rendering method by extracting the area >= 130 HU within the entire aorta. The total AC volume index (AC-VI) was estimated as the total AC volume divided by the body surface area. Results: In the 117 patients (64.7 +/- 13.1 years, 39% women), the median total AC-VI was 1.23 mL/m(2). The mean estimated glomerular filtration rate (eGFR), adjusted serum calcium levels, and serum phosphate levels were 63.8 +/- 19.9 mi./min/1.73 m(2), 9.1 +/- 0.4 mg/dL, and 3.6 +/- 0.6 mgidL, respectively. When the patients were classified into four quartiles based on their total AC-VI value, the serum phosphate level showed a positive correlation with a probability of being in the highest AC-VI quartile (R-2 = 0.0146, p = 0.0383) whereas the adjusted serum calcium level did not show a significant correlation (R-2 = 0.0040, p = 0.2615). A similar relationship between the serum phosphate level, adjusted serum calcium level, and AC-VI was confirmed when the total AC-VI was divided into the thoracic AC-VI and abdominal AC-VI. Multivariate analysis indicated that the serum phosphate level was an independent positive predictor of higher total AC-VI quartiles (beta = 0.8013, p = 0.0160). Conclusions: An increase in serum phosphate level was associated with an increased AC burden in non HD patients undergoing cardiovascular surgery. (C) 2015 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

The coronary sinus is located within the inferior pyramidal space, which is the part of the epicardial visceral fibroadipose tissue wedging between the four cardiac chambers from the bottom of the heart. Therefore, this region is susceptible to the morphological changes of the cardiac chambers. We present a case of slit-like deformation of the coronary sinus orifice due to compression of the inferior pyramidal space by the severely dilated left ventricle, which has not been previously described.

Cardiologists are increasingly becoming involved in procedures associated with the atrial septum and ventricular septum, such as transseptal puncture and selective site pacing. Moreover, detailed knowledge about the architecture of the atrial septum and ventricular septum is now available from studies by radiologists and anatomists. However, from the viewpoint of clinical cardiologists, many questions about the three-dimensional cardiac structural anatomy that relate closely to routine invasive procedures remain unresolved. Although modern multidetector-row computed tomography could provide answers, interventional cardiologists might have not considered the potential of this equipment, as only a few have performed studies with both radiological imaging and cadaveric hearts. Detailed knowledge of the three-dimensional fluoroscopic cardiac structural anatomy could help to reduce the need for contrast medium injection and radiation exposure, and to perform safe interventions. In this article, we present a series of cardiac structural images, including images of the atrial septum and ventricular septum, reconstructed in combination with the cardiac contour using multidetector-row computed tomography. We also discuss the clinical implications of the findings on the basis of accumulated insights of research pioneers. We hope that the present images will serve as a bridge between the fields of cardiology, radiology, and anatomy, and encourage cardiologists to integrate their accumulated insights into the three-dimensional clinical images of the living heart. Clin. Anat. 29:342-352, 2016. (c) 2015 Wiley Periodicals, Inc.

It is essential for the interventional cardiologist to have in-depth anatomical information about the three-dimensional arrangement and location of the cardiac valves relative to the various projections of the cardiac contour as revealed fluoroscopically. Multidetector-row computed tomography is useful for providing information about the three-dimensional arrangements of each structure. This article presents cardiac structural images, focusing on the arrangement and location of the cardiac valves, which were reconstructed with the cardiac contour and surrounding structures using multidetector-row computed tomography. We discuss the clinical implications of the findings. We hope these images will serve as a bridge between cardiology, radiology, and anatomy, and will prompt scientists in the field of cardiology to integrate their accumulated insights into three-dimensional clinical images of the living heart. Clin. Anat. 29:364-370, 2016. (c) 2015 Wiley Periodicals, Inc.

The left ventricular outflow tract (LVOT) is a common site of idiopathic ventricular arrhythmia. Many electrocardiographic characteristics for predicting the origin of arrhythmia have been reported, and their prediction rates are clinically acceptable. Because these approaches are inductive, based on QRS-wave morphology during the arrhythmia and endocardial or epicardial pacing, three-dimensional anatomical accuracy in identifying the exact site of the catheter position is essential. However, fluoroscopic recognition and definition of the anatomy around the LVOT can vary among operators, and three-dimensional anatomical recognition within the cardiac contour is difficult because of the morphological complexity of the LVOT. Detailed knowledge about the three-dimensional fluoroscopic cardiac structural anatomy could help to reduce the need for contrast medium injection and radiation exposure, and to perform safe interventions. In this article, we present a series of structural images of the LVOT reconstructed in combination with the cardiac contour using multidetector-row computed tomography. We also discuss the clinical implications of these findings based on the accumulated insights of research pioneers. Clin. Anat. 29:353-363, 2016. (c) 2015 Wiley Periodicals, Inc.

Background: Recently several publications described the diagnostic value of coronary CT angiography (coronary CTA) derived fractional flow reserve (CTA-FFR). For a recently introduced on-site CTA-FFR application, detailed methodology and factors potentially affecting performance have not yet been described. Objective: To provide a methodological background for an on-site CTA-FFR application and evaluate the effect of patient and acquisition characteristics. Methods: The on-site CTA-FFR application utilized a reduced-order hybrid model applying pressure drop models within stenotic regions. In 116 patients and 203 vessels the diagnostic performance of CTA-FFR was investigated using invasive FFR measurements as a reference. The effect of several potentially relevant factors on CTA-FFR was investigated. Results: 90 vessels (44%) had a hemodynamically relevant stenosis according to invasive FFR (threshold <= 0.80). The overall vessel-based sensitivity, specificity and accuracy of CTA-FFR were 88% (CI 95%: 79 -94%), 65% (55-73%) and 75% (69-81%). The specificity was significantly lower in the presence of misalignment artifacts (25%, CI: 6-57%). A non-significant reduction in specificity from 74% (60-85%) to 48% (26-70%) was found for higher coronary artery calcium scores. Left ventricular mass, diabetes mellitus and large vessel size increased the discrepancy between invasive FFR and CTA-FFR values. Conclusions: On-site calculation of CTA-FFR can identify hemodynamically significant CAD with an overall per-vessel accuracy of 75% in comparison to invasive FFR. The diagnostic performance of CTA-FFR is negatively affected by misalignment artifacts. CTA-FFR is potentially affected by left ventricular mass, diabetes mellitus and vessel size. (C) 2016 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Backgrounds. This study examines the hypothesis that four-dimensional noise reduction (4DNR) with short interval times reduces noise in cardiac computed tomography (CCT) using "padding" phases. Furthermore, the capability of reducing the reduction dose in CCT using this post-processing technique was assessed. Methods. Using base and quarter radiation doses for CCT (456 and 114 mAs/rot with 120 kVp), a static phantom was scanned ten times with retrospective electrocardiogram gating, and 4DNR with short interval times (50 ins) was performed using a post-processing technique. Differences in the computed tomography (CT) attenuation,contrast-to-noise ratio (CNR) and spatial resolution with modulation transfer function in each dose image obtained with and without 4DNR were assessed by conducting a Tukey-Kramer's test and non-inferiority test. Results. For the base dose, by using 4DNR, the CNR was improved from 1.18 +/- 0.15 to 2.08 +/- 0.20 (P = 0.001), while the CT attenuation and spatial resolution of the image of 4DNR did not were significantly inferior to those of reference image (P < 0.001). CNRs of the quarter-dose image in 4DNR also improved to 1.28 +/- 0.11, and were not inferior to those of the non-4DNR images of the base dose (P < 0.001). Conclusions. 4DNR with short interval times significantly reduced noise. Furthermore, applying this method to CCT would have the potential of reducing the radiation dose by 75%, while maintaining a similar image noise level.

A 23-year-old asymptomatic woman was referred to our hospital for further examination of a systolic ejection murmur with fixed splitting of the second heart sound auscultated at the third left sternal border. Initial echocardiography could not detect the cause. Subsequently performed low-dose computed tomography, however, ruled out the possibility of any congenital heart diseases, but revealed a markedly shortened anteroposterior diameter of the chest, which led us to a diagnosis of straight back syndrome. A vertically oriented "pan-cake" appearance of the heart, straight vertebral column, and compression of the right ventricular outflow tract were clearly demonstrated on the reconstructed images.

BACKGROUND AND PURPOSE: Pretreatment diagnosis for the location of shunts and arterial feeders of spinal arteriovenous fistulas is crucial. This study aimed to evaluate the utility of subtracted CT angiography imaging by using nonrigid registration (R-CTA) in patients with spinal arteriovenous fistulas compared with conventional CTA imaging. MATERIALS AND METHODS: The records of 15 consecutive subjects (mean age, 65 years; 2 women) who had undergone CTA and digital subtraction angiography for clinically suspected spinal arteriovenous fistula were reviewed. From CTA images obtained at the arterial and late arterial phases, warped images of the late arterial phase were obtained by using nonrigid registration that was adjusted to the arterial phase images. R-CTA images were then obtained by subtracting the warped images from the arterial phase images. The accuracies of using nonrigid registration and conventional spinal CTA and the time required for detecting arterial feeders in spinal arteriovenous fistulas were analyzed for each patient with DSA results as a standard reference. The difference between R-CTA and conventional spinal CTA was assessed by the Welch test and the McNemar chi(2) test. RESULTS: R-CTA had a higher accuracy compared with conventional spinal CTA (80% versus 47%, P=.025). The time for interpretation was reduced in R-CTA compared with conventional spinal CTA (45.1 versus 97.1 seconds, P=.002). CONCLUSIONS: Our subtracted CTA imaging by using nonrigid registration detects feeders of spinal arteriovenous fistulas more accurately and quickly than conventional CTA.

The inferior pyramidal space (IPS) comprises the epicardial visceral adipose tissue wedged between the bottoms of the four cardiac chambers from the postero-inferior epicardial surface of the heart. Understanding the complex anatomy around the IPS is important for clinical cardiologists. Although leading anatomists and radiologists have clarified the anatomy of the IPS in detail, few studies have demonstrated this anatomy in three dimensions. The aim of this study was to visualize the three-dimensional anatomy of the IPS reconstructed from the living heart using multidetector-row computed tomography. We also developed an original paper model of the IPS to enhance understanding of its intricate structure. Clin. Anat. 28:878-887, 2015. (c) 2014 Wiley Periodicals, Inc.

Clinical Anatomy of the Inferior Pyramidal Space Although many studies have described the detailed anatomy of the inferior pyramidal space, it may not be easy for cardiologists who have few chances to study cadaveric hearts to understand the correct morphology of the structure. The inferior pyramidal space is the part of extracardiac fibro-adipose tissue wedging between the 4 cardiac chambers from the diaphragmatic surface of the heart. Many cardiologists have interests in pericardial adipose tissue, but the inferior pyramidal space seems to have been neglected. A number of important structures, including the coronary sinus, atrioventricular node, atrioventricular nodal artery, membranous septum, muscular atrioventricular sandwich (previously called the muscular atrioventricular septum), atrial septum, ventricular septum, aortic valvar complex, mitral valvar attachment, and tricuspid valvar attachment are associated with the inferior pyramidal space. We previously revealed its 3-dimensional live anatomy using multidetector-row computed tomography. Moreover, the 3-dimensional understanding of the anatomy in association with the cardiac contour is important from the viewpoints of clinical cardiac electrophysiology. The purpose of this article is to demonstrate extended findings regarding the clinical structural anatomy of the inferior pyramidal space, which was reconstructed in combination with the cardiac contour using multidetector-row computed tomography, and discuss the clinical implications of the findings.

Separate assessment of changes in blood oxygenation and blood volume is required in blood oxygen level-dependent (BOLD) imaging. We developed a calculated echo time (TE) imaging technique designed to minimize effects of blood oxygenation and to evaluate blood volume specifically. Dynamic 3T multi-echo BOLD images of calf muscle were acquired from six healthy volunteers by use of a cuff-compression model. Calculated TE images at TE = 0 ms (cTE(0)) and map () were calculated from acquired multi-echo images. The time courses of the mean value for the entire calf muscles in cTE(0), in acquired BOLD images at TE = 45.2 ms (aTE(45)), and in were obtained. The Euclidean distances between the two pairs of time courses were calculated: distance between aTE(45) and (D (at)), and that between cTE(0) and (D (ct)). The difference between D (at) and D (ct) was tested by use of the Wilcoxon signed rank test. D (at) was significantly different from D (ct) (P = 0.031), indicating that the time course of cTE(0) was significantly different from that of blood oxygenation-weighted images ( and aTE(45)). The effect of blood oxygenation could be minimized using cTE(0). Thus, signal intensity changes of cTE(0) reflected changes in blood volume more specifically.

An optimal image intensifier angulation used for obtaining an en face view of a target structure is important in electrophysiologic procedures performed around each coronary aortic sinus (CAS). However, few studies have revealed the fluoroscopic anatomy of the target area. This study investigated the optimal angulation for each CAS and the interventricular septum (IVS). The study included 102 consecutive patients who underwent computed tomography coronary angiography. The optimal angle for each CAS was determined by rotating the volume-rendered image around the vertical axis. The angle formed between the anteroposterior axis and IVS was measured using the horizontal section. The frontal direction was defined as zero, positive, or negative if the en face view of the target CAS was obtained in the frontal view, left anterior oblique (LAO) direction, or right anterior oblique (RAO) direction, respectively. The optimal angles for the left, right, and non-CASs were 120.3 +/- 10.5 degrees, 4.8 +/- 16.3 degrees, and -110.0 +/- 13.8 degrees, respectively. The IVS angle was 42.6 +/- 8.5 degrees. Accordingly, the optimal image intensifier angulations for the left, right, and non-CASs and the IVS were estimated to be RAO 60 degrees, LAO 5 degrees, LAO 70 degrees, and RAO 50 degrees, respectively. The IVS angle was the most common independent predictor of the optimal angle for each CAS. Differences in the optimal angulations for each CAS and the IVS are demonstrated. The biplane angulation needs to be tailored according to the individual patients and target structures for electrophysiologic procedures. Clin. Anat. 28:494-505, 2015. (c) 2015 Wiley Periodicals, Inc.

Objective: Three-dimensional (3-D) visualization and quantification of vascular calcification (VC) are important to accelerate the multidisciplinary investigation of VC. Agatston scoring is the standard approach for evaluating coronary artery calcification. However, regarding aortic calcification (AC), quantification methods appear to vary among studies. The aim of this study was to introduce a simple technique of simultaneous quantification and 3-D visualization of AC and provide validation data. Methods: The main study comprised of 126 patients who underwent the thoracoabdominal plain computed tomography scan as preoperative general evaluation. AC was quantified using a volume-rendering (VR) method (VR AC volume) by extracting the volume with a density >= 130 HU within the total aorta. The concordance and reproducibility of the VR AC volume were validated in comparison with the conventional slice-by-slice voxel-based AC quantification (volumetric AC score) using the Agatston scoring software. Results: Excellent concordance between the VR AC volume and volumetric AC score was confirmed (Spearman correlation coefficient = 0.9997, mean difference = -0.05 +/- 0.23 mL, p < 0.0001). Excellent intraobserver and interobserver reliabilities were demonstrated using the Bland -Altman analysis as the mean intraobserver difference was 0.00 mL (p = 0.9863) and the mean interobserver difference was -0.01 mL (p = 0.6612). Conclusion: The VR method was validated to be feasible. This simple approach could overcome the limitation of the current method based on slice-by-slice pixel or voxel summation, which lacks 3-D visual information. Accordingly, this approach would be promising for accelerating the investigation of VC. (C) 2014 Elsevier Ireland Ltd. All rights reserved.

Purpose: To validate an on-site algorithm for computation of fractional flow reserve (FFR) from coronary computed tomographic (CT) angiography data against invasively measured FFR and to test its diagnostic performance as compared with that of coronary CT angiography. Materials and Methods: The institutional review board provided a waiver for this retrospective study. From coronary CT angiography data in 106 patients, FFR was computed at a local workstation by using a computational fluid dynamics algorithm. Invasive FFR measurement was performed in 189 vessels (80 of which had an FFR <= 0.80); these measurements were regarded as the reference standard. The diagnostic characteristics of coronary CT angiography-derived computational FFR, coronary CT angiography, and quantitative coronary angiography were evaluated against those of invasively measured FFR by using C statistics. Sensitivity and specificity were compared by using a two-sided McNemar test. Results: For computational FFR, sensitivity was 87.5% (95% confidence interval [CI]: 78.2%, 93.8%), specificity was 65.1% (95% CI: 55.4%, 74.0%), and accuracy was 74.6% (95% CI: 68.4%, 80.8%), as compared with the finding of lumen stenosis of 50% or greater at coronary CT angiography, for which sensitivity was 81.3% (95% CI: 71.0%, 89.1%), specificity was 37.6% (95% CI: 28.5%, 47.4%), and accuracy was 56.1% (95% CI: 49.0%, 63.2%). C statistics revealed a larger area under the receiver operating characteristic curve (AUC) for computational FFR (AUC, 0.83) than for coronary CT angiography (AUC, 0.64). For vessels with intermediate (25%69%) stenosis, the sensitivity of computational FFR was 87.3% (95% CI: 76.5%, 94.3%) and the specificity was 59.3% (95% CI: 47.8%, 70.1%). Conclusion: With use of a reduced-order algorithm, computation of the FFR from coronary CT angiography data can be performed locally, at a regular workstation. The diagnostic accuracy of coronary CT angiography-derived computational FFR for the detection of functionally important coronary artery disease (CAD) was good and was incremental to that of coronary CT angiography within a population with a high prevalence of CAD. (C)RNSA, 2014.

Purpose An MRI-based pre-test to determine the probability of pediatric leukemia prior to bone marrow aspiration would be useful to prevent unnecessary exposure to this invasive test. We aimed to evaluate the clivus-to-pons signal intensity ratio (CPR) and visual scoring (VS) on T-1-weighted images (T1WI) and diffusion-weighted images (DWI) to distinguish pediatric leukemia patients from normal controls. Materials and methods We retrospectively reviewed 1.5-T brain MR images of 13 consecutive leukemia patients (3 girls, 10 boys; mean age, 8.23 years; range, 1-17 years) and 40 age- and gender-matched normal controls. We evaluated differences between leukemia patients and normal controls using Wilcoxon rank-sum and Mann-Whitney U tests with respect to the following parameters: (1) CPR on T1WI (CPRT1WI); (2) CPR on DWI (CPRDWI); (3) VS on T1WI (VST1WI); and (4) VS on DWI (VSDWI). Results The CPRT1WI values for leukemia patients and normal controls were 0.77 +/- 0.12 and 1.39 +/- 0.47, respectively (P < 0.001). The corresponding CPRDWI values were 1.03 +/- 0.38 and 0.50 +/- 0.17, respectively (P < 0.001). VST1WI and VSDWI were significantly different between the groups (P < 0.001 for both). Conclusion MRI-based quantitative and qualitative analyses of clival bone marrow on T1WI and DWI can distinguish pediatric leukemia patients from normal subjects.

Objectives The purpose of this study was to estimate the myocardial area at risk (MAAR) using coronary computed tomography angiography (CTA) and Voronoi algorithm-based myocardial segmentation in comparison with single-photon emission computed tomography (SPECT). Methods Thirty-four patients with coronary artery disease underwent 128-slice coronary CTA, stress/rest thallium-201 SPECT, and coronary angiography (CAG). CTA-based MAAR was defined as the sum of all CAG stenosis (>50 %) related territories (the ratio of the left ventricular volume). Using automated quantification software (17-segment model, 5-point scale), SPECT-based MAAR was defined as the number of segments with a score above zero as compared to the total 17 segments by summed stress score (SSS), difference (SDS) score map, and comprehensive SPECT interpretation with either SSS or SDS best correlating CAG findings (SSS/SDS). Results were compared using Pearson's correlation coefficient. Results Forty-nine stenoses were observed in 102 major coronary territories. Mean value of CTA-based MAAR was 28.3 +/- 14.0 %. SSS-based, SDS-based, and SSS/SDS-based MAAR was 30.1 +/- 6.1 %, 20.1 +/- 15.8 %, and 26.8 +/- 15.7 %, respectively. CTA-based MAAR was significantly related to SPECT-based MAAR (r=0.531 for SSS; r=0.494 for SDS; r=0.814 for SSS/SDS; P<0.05 in each). Conclusions CTA-based Voronoi algorithm myocardial segmentation reliably quantifies SPECT-based MAAR.

Purpose: The role of early stage functional assessment of muscle blood flow response (MFR) by dynamic muscle blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging is unknown. We investigated the effect of smoking on vascular function according to MFR derived from dynamic muscle BOLD MR imaging during postocclusive reactive hyperemia in young smokers and nonsmokers. Methods: Sixteen healthy male volunteers (8 smokers, 8 nonsmokers; mean age, 30.4 +/- 4.6 years) underwent BOLD MR imaging of the left calf muscle. During reactive hyperemia provoked by a cuff-compression technique, we measured muscle BOLD (mB) using a 3-tesla single-shot multi-echo gradient-echo echo-planar imaging sequence. The 2 key mB variables in the reactive hyperemic phase that we studied were times to half hyperemic peak (T-1/2peak) and peak (TTP), each measured from cuff deflation. We used the Welch test to assess differences in these between smokers and nonsmokers. Results: T-1/2peak and TTP were significantly longer in smokers (P < 0.05) in reactive hyperemia. T-1/2peak was 13.8 +/- 5.4s in smokers and 7.6 +/- 1.5 s in nonsmokers, and TTP was 67.5 +/- 18.8 s in smokers and 45.4 +/- 7.1 s in nonsmokers. Conclusion: Dynamic BOLD MR imaging of calf muscle during postocclusive reactive hyperemia demonstrated statistically significant differences in T-1/2peak and TTP between young smokers and nonsmokers, indicating the presence of early stage smoking-related deterioration in MFR.

Fistulas between systemic and pulmonary arteries are associated with various underlying etiologies and cause pulmonary hypertension (PH). Diagnosis of this condition requires several imaging studies and the exclusion of other possible causes of PH. We herein report a case of a patient with interstitial pneumonia and scleroderma. The imaging revealed multiple fistulas involving the inferior phrenic and left lower pulmonary arteries. The fistulas were closed using coils, but the PH remained presumably due to other undiagonosed fistulas. The improvement of symptoms following use of a supplementary pulmonary vasodilator provides the hope that the chosen treatment could be a viable alternative approach for other similar cases.

This study aimed to develop software for tumor segmentation on 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). To segment the tumor from the background, we used graph cut, whose segmentation energy was generally divided into two terms: the unary and pairwise terms. Locally connected conditional random fields (LCRF) was proposed for the pairwise term. In LCRF, a three-dimensional cubic window with length L was set for each voxel, and voxels within the window were considered for the pairwise term. To evaluate our method, 64 clinically suspected metastatic bone tumors were tested, which were revealed by FDG-PET. To obtain ground truth, the tumors were manually delineated via consensus of two board-certified radiologists. To compare the LCRF accuracy, other types of segmentation were also applied such as region-growing based on 35%, 40%, and 45% of the tumor maximum standardized uptake value (RG35, RG40, and RG45, respectively), SLIC superpixels (SS), and region-based active contour models (AC). To validate the tumor segmentation accuracy, a dice similarity coefficient (DSC) was calculated between manual segmentation and result of each technique. The DSC difference was tested using the Wilcoxon signed rank test. The mean DSCs of LCRF at L = 3, 5, 7, and 9 were 0.784, 0.801, 0.809, and 0.812, respectively. The mean DSCs of other techniques were RG35, 0.633 RG40, 0.675 RG45, 0.689 SS, 0.709 and AC, 0.758. The DSC differences between LCRF and other techniques were statistically significant (p < 0.05). In conclusion, tumor segmentation was more reliably performed with LCRF relative to other techniques.

Objective Metaiodobenzylguanidine (MIBG) scintigraphy is used to assess heart failure (HF) severity and to predict cardiac functional recovery. Cardiovascular magnetic resonance (CMR) imaging has recently been used to diagnosis HF. We evaluated CMR T2 mapping and MIBG scintigraphy in dilated cardiomyopathy (DCM) patients. Methods Consecutively, 22 DCM patients [aged 56.8 +/- 13.4 years; 6 women and 16 men; left ventricular ejection fraction (LVEF), 31.9 +/- 10.7%] who underwent T2 mapping and MIBG scintigraphy were retrospectively evaluated. Echocardiography results were recorded at baseline and the 6-month follow-up. Patients with an increased LVEF >= 15% between the 2 measures were considered to be responders. We measured each patient's T2 values and MIBG indices [the heart-to-mediastinum ratio (H/M) in the early phase, H/M in the delayed phase, and the washout rate (WOR)] at baseline. We compared these values between the 12 responders and 10 non-responders. Results The mean T2 value for all patients was 64.5 +/- 6.6 ms. The mean values of early H/M, delayed H/M, and WOR were 2.06 +/- 0.25, 1.94 +/- 0.35, and 43.5 +/- 11.8%, respectively. The T2 values were found to correlate with MIBG indices (p<0.05 for all) and were lower in the responders than non-responders (61.4 vs. 68.1 ms, p=0.013). MIBG indices were not significantly different. Conclusion Our study shows that the T2 values correlated with the MIBG indices and were increased in non-responders. T2 mapping may be useful in assessing the cardiac function and functional recovery in DCM patients.

This study aimed to develop software for tumor segmentation on 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET). To segment the tumor from the background, we used graph cut, whose segmentation energy was generally divided into two terms: the unary and pairwise terms. Locally connected conditional random fields (LCRF) was proposed for the pairwise term. In LCRF, a three-dimensional cubic window with length L was set for each voxel, and voxels within the window were considered for the pairwise term. To evaluate our method, 64 clinically suspected metastatic bone tumors were tested, which were revealed by FDG-PET. To obtain ground truth, the tumors were manually delineated via consensus of two board-certified radiologists. To compare the LCRF accuracy, other types of segmentation were also applied such as region-growing based on 35%, 40%, and 45% of the tumor maximum standardized uptake value (RG35, RG40, and RG45, respectively), SLIC superpixels (SS), and region-based active contour models (AC). To validate the tumor segmentation accuracy, a dice similarity coefficient (DSC) was calculated between manual segmentation and result of each technique. The DSC difference was tested using the Wilcoxon signedrank test. The mean DSCs of LCRF at L = 3, 5, 7, and 9 were 0.784, 0.801, 0.809, and 0.812, respectively. The mean DSCs of other techniques were RG35, 0.633; RG40, 0.675; RG45, 0.689; SS, 0.709; and AC, 0.758. The DSC differences between LCRF and other techniques were statistically significant (p < 0.05). In conclusion, tumor segmentation was more reliably performed with LCRF relative to other techniques.

Objectives: Quantitative myocardial perfusion imaging by computed tomography (CT) was recently introduced to calculate myocardial blood flow (MBF). Because absolute MBF thresholds may be affected by technique, methodology, and the microvasculature, we investigated whether a relative measure of MBF improves accuracy to identify hemodynamically significant coronary stenosis. Materials and Methods: In this prospective study, 42 patients (mean [SD] age, 62.3[8.7] years; 8 women) with suspected or known coronary disease underwent dynamic CT myocardial perfusion imaging using adenosine vasodilation, before invasive angiography (coronary angiography) with fractional flow reserve (FFR). Within each myocardial territory MBF, the MBF relative to remote myocardium (MBFratio) was calculated and compared with coronary angiography and FFR. Results: Of the 91 vessels interrogated by FFR (median, 0.81; interquartile range, 0.73-0.94), 45 vessels (49%) had an FFR value lower than 0.8 and were considered hemodynamically significant. Hyperemic MBF was lower in ischemic territories: 75.6 +/- 22.5 mL per 100 mL/min versus 98.3 +/- 23.1 mL per 100 mL/min (P < 0.0001). The MBFratio correlated better with FFR (P = 0.76) than the absolute MBF did (P = 0.52). Receiver operating curve analysis showed better discrimination by MBFratio: area under the curve of 0.85 versus 0.75 (P = 0.02). The MBF of remote myocardium varied between 60.7 and 167.2 mL per 100 mL/min and was lower in patients without heart rate acceleration (P = 0.0035). Conclusions: The MBFratio seems to better identify hemodynamically significant coronary artery disease than does the absolute MBF determined by dynamic CT perfusion imaging. This may be caused by microvascular status or related to the methodology.

To evaluate the details of myocardial dysfunction in dilated cardiomyopathy (DCM) patients using tagging images and the correlation of tagging imaging with tissue characteristics. Circumferential strain (Ecc) derived from tagging images was measured in 15 normal (NML) subjects (15 males; mean age 28.5 years) and 12 DCM patients (7 males; mean age 48.9 years). The following parameters were compared: (1) the magnitude of peak Ecc (Ecc*); (2) the coefficient of variation of the time of Ecc* (CVtime*), which indexes dyssynchrony; and (3) descriptive findings of time-Ecc curves. We also evaluated the correlations of Ecc* in DCM patients with ejection fraction (EF), myocardial T2 values, and late gadolinium enhancement (LGE). Mean Ecc*s in DCM patients and NML subjects were -12.7 and -23.5 %, respectively (P < 0.0001). Mean CVtime*s were 15.2 and 4.5 %, respectively (P = 0.0002). The findings of pre-systolic extension and systolic stretch in the septum were observed in 6 (50 %) and 10 (83.3 %) DCM patients and in none of the NML participants. Ecc* was correlated with EF (P < 0.0001, R (2) = 0.90) and T2 values (P = 0.018, R (2) = 0.44) but not with LGE (P = 0.072, R (2) = 0.28). Tagging images revealed the reduction of myocardial function as well as dyssynchrony in DCM patients. Myocardial dysfunction occurred coincidently with myocardial inflammation.

Age-related morphological changes of the aorta, including dilatation and elongation, have been reported. However, rotation has not been fully investigated. We focused on the rotation of the ascending aorta and investigated its relationship with tortuosity. One hundred and two consecutive patients who underwent computed tomography coronary angiography were studied. The angle at which the en face view of the volume-rendered image of the right coronary aortic sinus (RCS) was obtained without foreshortening was defined as the rotation index. It was defined as zero if the RCS was squarely visible in the frontal view, positive if it rotated clockwise toward the left anterior oblique (LAO) direction, and negative if it rotated counter-clockwise toward the right anterior oblique (RAO) direction. The tortuosity was evaluated by measuring the biplane tilt angles formed between the ascending aorta and the horizontal line. The mean rotation index, posterior tilt angle viewed fromthe RAO direction (alpha(RAO)), and anterior tilt angle viewed from the LAO direction (alpha(LAO)) were 4.8 +/- 16.3, 60.7 +/- 7.0 degrees, and 63.6 +/- 9.0 degrees, respectively. Although no correlation was observed between the rotation index and the alpha(LAO) (beta=-0.0761, P=0.1651), there was a significant negative correlation between the rotation index and alpha(RAO) (beta=-0.1810, P<0.0001). In multivariate regression analysis, the rotation index was an independent predictor of the alpha(RAO) (beta=-0.1274, P50.0008). Clockwise rotation of the proximal ascending aorta exacerbates the tortuosity by tilting the aorta toward the posterior direction. (C) 2014 Wiley Periodicals, Inc.

Myocardial edema and inflammation play an important role in dilated cardiomyopathy (DCM). This pathologic condition can be identified noninvasively using cardiovascular magnetic resonance imaging (CMR). The purpose of this study was to determine the effectiveness of T2 values obtained with T2 mapping in the detection of edema in DCM patients, compared with that of conventional T2-weighted imaging (T2WI). CMR was used for 15 normal controls (NML) and 26 DCM patients. The DCM patients were classified as having either mild dysfunction with a left ventricular ejection fraction (EF) > 35 % or severe dysfunction with an EF a parts per thousand currency sign35 %. Myocardial edema was assessed by both T2 mapping and T2WI. The differences between the T2 values determined from T2 mapping and the T2 ratios that were calculated from the T2WI were compared among the NML, mild DCM, and severe DCM patients. The T2 values for the NML, mild DCM, and severe DCM patients were 51.2 +/- A 1.6, 61.2 +/- A 0.37, and 67.4 +/- A 6.8, respectively (P < 0.05 for each pair), and the corresponding T2 ratios were 1.88 +/- A 0.09, 2.12 +/- A 0.37, and 2.04 +/- A 0.34, respectively (P > 0.05). T2 mapping clearly showed that the myocardial water content was larger in DCM patients than in NML controls and that the myocardial water content increased as the disease progressed. Thus, T2 mapping is a useful technique for the diagnosis and quantitation of diffuse myocardial edema.

Purpose: To ascertain the role of respiratory-gated PET/CT with F-18-fluorodeoxyglucose (F-18-FDG) for accurate diagnosis of liver metastasis. Materials and methods: Forty patients with suspected liver metastasis underwent conventional whole-body PET/CT scan initially, followed by respiratory-gated PET/CT scan covering the liver. Visual detectability (using a 5-point confidence scale), maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) of hepatic metastatic lesions were assessed for three data sets including ordinary whole-body (WB) scan, and non-respiratory-gated (nRG) and respiratory-gated (RG) scans. Results of enhanced CT and/or MRI, or clinical and radiological follow-up were used for reference. Results: Sixteen of the patients were found to have 53 metastatic lesions in the liver. Patient-based accuracy of WB, nRG, and RG was 92.5%, 95.0%, and 97.5%, respectively, with a lesion-based detection rate of 67.9%, 73.6%, and 73.6%, respectively. The average SUVmax of 34 liver metastatic lesions for WB, nRG, and RG was 6.60 +/- 2.34, 7.19 +/- 2.66, and 8.08 +/- 3.24, respectively. SUVmax for RG was significantly higher than that for WB (p = 0.0069). The average MTV of these 40 lesions for the three protocols was 5.32 +/- 4.78 cm(3), 5.07 +/- 4.73 cm(3), and 4.73 +/- 4.67 cm(3), respectively. Among the three protocols, RG showed the best visual and quantitative evaluation for diagnosis of liver metastasis. Conclusion: Respiratory-gated PET/CT allows more accurate identification of liver metastases than nonrespiratory-gated PET/CT. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

Background and Purpose:Dural ectasia is well recognized in Marfan syndrome (MFS) as one of the major diagnostic criteria, but the exact prevalence of dural ectasia is still unknown in Loeys-Dietz syndrome (LDS), which is a recently discovered connective tissue disease. In this study, we evaluated the prevalence of dural ectasia in LDS according by using qualitative and quantitative methods and compared our findings with those for with MFS and normal controls.Material and Methods:We retrospectively studied 10 LDS (6 males, 4 females, mean age 36.3 years) and 20 MFS cases (12 males, 8 females, mean age 37.1 years) and 20 controls (12 males, 8 females, mean age 36.1 years) both qualitatively and quantitatively using axial CT images and sagittal multi-planar reconstruction images of the lumbosacral region. For quantitative examination, we adopted two methods: method-1 (anteroposterior dural diameter of S1> L4) and method-2 (ratio of anteroposterior dural diameter/vertebral body diameter> cutoff values). The prevalence of dural ectasia among groups was compared by using Fisher's exact test and the Tukey-Kramer test.Results:In LDS patients, the qualitative method showed 40% of dural ectasia, the quantitative method-1 50%, and the method-2 70%. In MFS patients, the corresponding prevalences were 50%, 75%, and 85%, and in controls, 0%, 0%, and 5%. Both LDS and MFS had a significantly wider dura than controls.Conclusions:While the prevalence of dural ectasia varied depending on differences in qualitative and quantitative methods, LDS as well as MFS, showed, regardless of method, a higher prevalence of dural ectasia than controls. This finding should help the differentiation of LDS from controls. © 2013 Kono et al.

A variety of different tumors can arise from any of the tissues present in the retroperitoneum, and they exhibit a wide range of pathologic types. Although computed tomography (CT) and magnetic resonance imaging (MRI) can demonstrate important characteristics of these tumors, diagnosis is often challenging for radiologists. The purpose of this pictorial essay is to review F-18-fluorodeoxyglucose positron emission tomography/CT (FDG-PET/CT) features of different kinds of benign and malignant retroperitoneal tumors in comparison with CT or MRI findings alone and to become familiar with the wide variety of imaging characteristics.

Purpose: Myocardial fibrosis is considered to be an important factor in myocardial dysfunction and sudden cardiac death in hypertrophic cardiomyopathy (HCM). The purpose of this study was to compare myocardial fibrosis detected by late gadolinium enhancement (LGE) on cardiac MRI with myocardial perfusion and fatty acid metabolism assessed by single photon emission computed tomography in HCM. Materials and Methods: We retrospectively evaluated 20 consecutive HCM patients (female, 7 mean age, 53.4 years) who underwent LGE, technetium-99m methoxyisobutylisonitrile/tetrofosmin (99mTc-MIBI/tetrofosmin), and iodine-123 beta-methyl-iodophenylpentadecanoic acid (123I-BMIPP) imaging. We calculated the myocardium-to-lumen signal ratio (M/L) for LGE in 17 segments based on the American Heart Association statement. Scoring of 99mTc-MIBI/tetrofosmin (PI) and 123I-BMIPP (BM) was performed for each segment using a 5-point scale (0, normal 4, highly decreased). Results: Nineteen of 20 patients (95%) and 153 of 340 segments (45%) showed LGE. M/Ls were 0.42±0.16, 0.55±0.17, and 0.65±0.24 in PI0/BM0, PI0/BM1-4 and PI1-4/BM1-4, respectively. All M/Ls were significantly higher than that of a normal control (0.34±0.14) (p< 0.001). Conclusions: Myocardial fibrosis in HCM can occur despite normal perfusion and fatty acid metabolism, and is more strongly associated with disorders of fatty acid metabolism than with perfusion abnormalities. M/L may be a useful indicator of disease severity.

Identification of the Adamkiewicz artery (AKA) using CT angiography (CTA) is crucial in patients with thoracic aortic aneurysm (TAA) or aortic dissection (AD). The purpose of this study was to compare the AKA detection rate of intravenous injection with a 64-slice MDCT (IV64) versus a 16-slice MDCT (IV16) as well as by CTA using intra-arterial injection with a 16-slice MDCT (IA16). A retrospective review of 160 consecutive patients who underwent CTA was performed. There were 108 TAA and 52 AD cases, 105 of whom were examined with IV64, 15 with IV16, and 40 with IA16. The AKA detectability for each imaging method was assessed, and the factors influencing the detectability were analyzed by multivariate analysis. The detection rates for IV64, IV16, and IA16 were 85.7, 60.0, and 80.0 %, respectively, with IV64 being more sensitive than IV16 (P = 0.025). The detection rate for AD patients was 66.7 % with IV64, which was similar to IV16 (57.1 %) and IA16 (66.8 %). On the other hand, the detection rate for TAA patients was 93.3 % with IV64, which was higher than IV16 (62.5 %, P = 0.021) and similar to IA16 (88.0 %). Multivariate analysis demonstrated the independent factors for AKA detectability were TAA versus AD (P = 0.005, Odds ratio = 3.98) and IV64 versus IV16 (P = 0.037, Odds ratio = 4.03). The detection rate was higher for IV64 than for IV16, especially for TAA patients, while the rate was similar between IV64 and invasive IA16. A 64-slice MDCT thus provides a less invasive visualization of the AKA. © Springer Science+Business Media Dordrecht 2013.

Purpose: To evaluate potential benefits of using multiplanar reconstruction (MPR) in computer-aided detection (CAD) of lung nodules on multidetector computed tomography (MDCT). Materials and methods: MDCT datasets of 60 patients with suspected lung nodules were retrospectively collected. Using "second-read" CAD, two radiologists (Readers 1 and 2) independently interpreted these datasets for the detection of non-calcified nodules (>= 4mm) with concomitant confidence rating. They did this task twice, first without MPR (using only axial images), and then 4 weeks later with MPR (using also coronal and sagittal MPR images), where the total reading time per dataset, including the time taken to assess the detection results of CAD software (CAD assessment time), was recorded. The total reading time and CAD assessment time without MPR and those with MPR were statistically compared for each reader. The radiologists' performance for detecting nodules without MPR and the performance with MPR were compared using jackknife free-response receiver operating characteristic (JAFROC) analysis. Results: Compared to the CAD assessment time without MPR (mean, 69 s and 57 s for Readers 1 and 2), the CAD assessment time with MPR (mean, 46 s and 45 s for Readers 1 and 2) was significantly reduced (P < 0.001). For Reader 1, the total reading time was also significantly shorter in the case with MPR. There was no significant difference between the detection performances without MPR and with MPR. Conclusion: The use of MPR has the potential to improve the workflow in CAD of lung nodules on MDCT. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Purpose: To detect abnormal myocardial tissue in patients with diffuse myocardial disease, we propose a simple technique of late gadolinium enhancement (LGE) using routine myocardial imaging modalities. Materials and Methods: We retrospectively reviewed LGE Images from 51 patients with normal myocardium and 10 patients with pathologically proven cardiac amyloidosis (CA). We obtained sequential WE images from patients at 2, 5, 10, and 20 minutes after injection of Gd-DTPA (0.15 mmol/kg) with a fixed inversion time of 300 msec. We evaluated the signal intensity ratio of the myocardium to the left ventricular lumen (M/L) in one long and two short axial sections within 463 and 120 segments of normal myocardium and CA, respectively. Visually unenhanced and enhanced regions of myocardium were evaluated in each segment of patients with CA. Results: Among normal myocardium, M/L (means standard deviation; SD) was stable with time (2, 5, 10, and 20 min: 0.34 +/- 0.03, 0.31 +/- 0.05, 0.34 +/- 0.07, and 0.42 +/- 0.11, respectively). The calculated M/L of unenhanced (0.60 +/- 0.20, 0.68 +/- 0.19, 0.76 +/- 0.20, and 1.09 +/- 0.25, respectively) and enhanced myocardium (0.77 +/- 0.27, 0.99 +/- 0.29, 1.20 +/- 0.40, and 1.45 +/- 0.54, respectively) in patients with CA was significantly greater than that seen for the normal myocardium at each time and increased over time. Conclusion: In patients with CA, diffuse myocardial abnormalities can be demonstrated using M/L, and this technique may be useful for the characterization of other myocardial diseases.

Purpose: The purpose of this study was to determine the utility of three-dimensional (3D) automatic exposure control (AEC) for low-dose CT examination in a chest phantom study. Materials and methods: A chest CT phantom including simulated focal ground-glass opacities (GGOs) and nodules was scanned with a 64-detector row CT with and without AEC. Performance of 3D AEC included changing targeted standard deviations (SDs) of image noise from scout view. To determine the appropriate targeted SD number for identification, the capability of overall identification with the CT protocol adapted to each of the targeted SDs was compared with that obtained with CT without AEC by means of receiver operating characteristic analysis. Results: When targeted SD values equal to or higher than 250 were used, areas under the curve (Azs) of nodule identification with CT protocol using AEC were significantly smaller than that for CT protocol without AEC (p < 0.05). When targeted SD numbers at equal to or more than 180 were adapted, Azs of CT protocol with AEC had significantly smaller than that without AEC (p < 0.05). Conclusion: This phantom study shows 3D AEC is useful for low-dose lung CT examination, and can reduce the radiation dose while maintaining good identification capability and good image quality. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Purpose: The purpose of this study was to assess the influence of reconstruction algorithm on identification and image quality of ground-glass opacities (GGOs) and partly solid nodules on low-dose thin-section CT. Materials and methods: A chest CT phantom including simulated GGOs and partly solid nodules was scanned with five different tube currents and reconstructed by using standard(A) and newly developed (B) high-resolution reconstruction algorithms, followed by visually assessment of identification and image quality of GGOs and partly solid nodules by two chest radiologists. Inter-observer agreement, ROC analysis and ANOVA were performed to compare identification and image quality of each data set with those of the standard reference. The standard reference used 120 mA s in conjunction with reconstruction algorithm A. Results: Kappa values (kappa) of overall identification and image qualities were substantial or almost perfect (0.60 < kappa). Assessment of identification showed that area under the curve of 25 mA reconstructed with reconstruction algorithm A was significantly lower than that of standard reference (p < 0.05), while assessment of image quality indicated that 50 mA s reconstructed with reconstruction algorithm A and 25 mA s reconstructed with both reconstruction algorithms were significantly lower than standard reference (p < 0.05). Conclusion: Reconstruction algorithm may be an important factor for identification and image quality of ground-glass opacities and partly solid nodules on low-dose CT examination. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Late gadolinium enhancement (LGE) during cardiac magnetic resonance imaging (MRI) can be seen in patients with myocardial fibrosis accompanied by myocardial infarction and cardiomyopathy. Some idiopathic dilated cardiomyopathy (DCM) patients have fibrosis in the myocardium and show LGE during cardiac MRI. The purpose of this study was to investigate the clinical significance of LGE in patients with DCM. We recruited 32 DCM patients who had a left ventricular ejection fraction (LVEF) of < 40% by echocardiography and performed cardiac MRI. LGE images were obtained 15 min after injection of Gd-DTPA (0.1 mmol/kg) using an inversion recovery gradient echo sequence. We compared LGE(+) and LGE(-) groups in terms of their nonsustained ventricular tachycardia (NSVT) properties. We also compared LGE and the frequency of an implantable cardioverter defibrillator (ICD) implantation. In total, 18 patients (56.3%) had LGE and a higher incidence of NSVT (P = 0.01). ICD implantation was more frequent in the LGE(+) group (P = 0.04). Because the LGE(+) patients showed a higher incidence of NSVT and ICD implantation, cardiac MRI could prove to be a useful tool in the management of DCM patients.

Loeys-Dietz syndrome (LDS) is a connective tissue disease caused by mutations in the genes encoding the transforming growth factor-beta receptor (TGFBR). LDS is associated with aneurysms or dissections of the aorta similar to Marfan syndrome (MFS) as well as arterial tortuosity and aneurysms in the peripheral arteries. The purpose of this study was to evaluate the arterial diseases of LDS to differentiate it from MFS. A total of 10 LDS patients with an identified mutation in TGFBR (6 male, 4 female; mean age 36.3 years) and 20 MFS patients with an identified mutation in fibrilin-1 who were age- and sex-matched to the LDS subjects (12 male, 8 female; mean age 37.1 years) were reviewed. The prevalence of vertebral arterial tortuosity (VAT) and peripheral aneurysm (PAN) was studied using computed tomography angiography. In all, 9 of the 10 LDS patients had VAT, and five PANs were observed in 3 patients. In contrast, 8 (40%) of the MFS patients had VAT, and 1 patient had a PAN. LDS had a higher prevalence of VAT (P = 0.017) by Fisher's exact test. The VAT was highly prevalent among LDS patients. Thus, the presence of VAT has the potential to differentiate LDS from MFS.

Purpose: Loeys-Dietz syndrome (LDS) is a connective tissue disease caused by mutations in the genes encoding the transforming growth factor-β receptor (TGFBR). LDS is associated with aneurysms or dissections of the aorta similar to Marfan syndrome (MFS) as well as arterial tortuosity and aneurysms in the peripheral arteries. The purpose of this study was to evaluate the arterial diseases of LDS to differentiate it from MFS. Materials and methods: A total of 10 LDS patients with an identified mutation in TGFBR (6 male, 4 female mean age 36.3 years) and 20 MFS patients with an identified mutation in fibrilin-1 who were age- and sex-matched to the LDS subjects (12 male, 8 female mean age 37.1 years) were reviewed. The prevalence of vertebral arterial tortuosity (VAT) and peripheral aneurysm (PAN) was studied using computed tomography angiography. Results: In all, 9 of the 10 LDS patients had VAT, and five PANs were observed in 3 patients. In contrast, 8 (40%) of the MFS patients had VAT, and 1 patient had a PAN. LDS had a higher prevalence of VAT (P = 0.017) by Fisher's exact test. Conclusion: The VAT was highly prevalent among LDS patients. Thus, the presence of VAT has the potential to differentiate LDS from MFS. © 2010 Japan Radiological Society.

Purpose: Late gadolinium enhancement (LGE) during cardiac magnetic resonance imaging (MRI) can be seen in patients with myocardial fibrosis accompanied by myocardial infarction and cardiomyopathy. Some idiopathic dilated cardiomyopathy (DCM) patients have fibrosis in the myocardium and show LGE during cardiac MRI. The purpose of this study was to investigate the clinical significance of LGE in patients with DCM. Materials and methods: We recruited 32 DCM patients who had a left ventricular ejection fraction (LVEF) of < 40% by echocardiography and performed cardiac MRI. LGE images were obtained 15 min after injection of Gd-DTPA (0.1 mmol/kg) using an inversion recovery gradient echo sequence. We compared LGE(+) and LGE(-) groups in terms of their nonsustained ventricular tachycardia (NSVT) properties. We also compared LGE and the frequency of an implantable cardioverter defibrillator (ICD) implantation. Results: In total, 18 patients (56.3%) had LGE and a higher incidence of NSVT (P = 0.01). ICD implantation was more frequent in the LGE(+) group (P = 0.04). Conclusion: Because the LGE(+) patients showed a higher incidence of NSVT and ICD implantation, cardiac MRI could prove to be a useful tool in the management of DCM patients. © 2010 Japan Radiological Society.

Purpose: To compare the utility of phase contrast MR imaging (PC-MRI) for assessment of pulmonary flow and pressure estimation with that of right heart catheterization and echocardiography (cardiac US) in patients with pulmonary arterial hypertension (PAH). Materials and Methods: Twenty consecutive patients with suspected PAH underwent PC-MRI, cardiac US, and right heart catheterization. In each patient, PC-MRI was acquired by cine 2D-PC method on a 1.5 Tesla scanner, and stroke volume (SV) and pulmonary arterial systolic pressure (PASP) were assessed by using the modified Bernoulli's equation. To evaluate the agreements of SV and PASP among the three methods, correlations and limits of agreement among the three methods were statistically assessed by using the Bland-Altman's analyses. Results: The correlations and limits of agreement for SV and PASP between PC-MRI and catheterization (r = 0.96, r(2) = 0.94, 1.1 +/- 6.9 mL and r = 0.94, r(2) = 0.88, -3.2 +/- 14.5 mmHg, respectively) were better than between cardiac US and catheterization (r = 0.01, r(2) < 0.01, 8.9 +/- 42.1 mL and r = 0.86, r(2) = 0.72, -5.9 +/- 27.7 mmHg, respectively). Conclusion: PC-MRI is more compatible with right heart catheterization than cardiac US in pulmonary flow and pressure estimation.

We evaluated quantification of calcified carotid stenosis by dual-energy (DE) CTA and dual-energy head bone and hard plaque removal (DE hard plaque removal) and compared the results to those of digital subtraction angiography (DSA). Eighteen vessels (13 patients) with densely calcified carotid stenosis were examined by dual-source CT in the dual-energy mode (tube voltages 140 kV and 80 kV). Head bone and hard plaques were removed from the dual-energy images by using commercial software. Carotid stenosis was quantified according to NASCET criteria on MIP images and DSA images at the same plane. Correlation between DE CTA and DSA was determined by cross tabulation. Accuracies for stenosis detection and grading were calculated. Stenosis could be evaluated in all vessels by DE CTA after applying DE hard plaque removal. In contrast, conventional CTA failed to show stenosis in 13 out of 18 vessels due to overlapping hard plaque. Good correlation between DE plaque removal images and DSA images was observed (r (2) = 0.9504) for stenosis grading. Sensitivity and specificity to detect hemodynamically relevant (> 70%) stenosis was 100% and 92%, respectively. Dual-energy head bone and hard plaque removal is a promising tool for the evaluation of densely calcified carotid stenosis.

Purpose The aim of this study was to investigate the regional differences between the morphologic and functional changes in the same patients with frontotemporal dementia (FTD) using statistical parametric mapping and voxel-based morphometry (VBM). Methods Thirteen FTD patients (mean age, 64.9 years old; mean MMSE score, 17.7), 20 sex-matched Alzheimer's disease (AD) patients (mean age, 65.0 years old; mean MMSE score, 17.5), and 20 normal volunteers (mean age, 65.2 years old; mean MMSE score, 29.0) underwent both [ (18)F]FDG positron emission tomography and three-dimensional spoiled gradient echo MRI. Statistical parametric mapping was used to conduct a VBM analysis of the morphologic data, which were compared voxel by voxel with the results of a similar analysis of glucose metabolic data. Results FTD patients showed decreased grey matter volume and decreased glucose metabolism in the frontal lobe and anterior temporal lobe. In addition, there was a clear asymmetry in grey matter volume in FTD patients by the VBM analysis while the glucose metabolic data showed little asymmetry. In AD patients, glucose metabolic reduction occurred in the bilateral posterior cingulate gyri and parietal lobules while grey matter density decreased the least in the same patients. Conclusion In FTD, metabolic and morphologic changes occur in the bilateral frontal lobe and temporal lobe with a limited asymmetry whereas there was considerable discordance in the AD group.

This study aimed at prospectively compared efficacy of non-contrast-enhanced (non-CE) MRI and MDCT for management of pulmonary nodules. A total of 161 patients with 200 nodules underwent MDCT and non-CE MRI (T1WI, T2WI, and STIR) in conjunction with pathological and/or more than 2 years of follow-up examinations. To compare qualitative detection rates between both modalities, all nodules were visually assessed. To compare quantitative and qualitative diagnostic capabilities of MRI, calculation of contrast ratio and visual assessment of probability for malignancy in each nodule were performed. Then, detection rate and diagnostic capability were statistically compared. Although the overall detection rate of each MR sequence (82.5%) was significantly lower than that of MDCT (97.0%, p < 0.05), that of malignant nodules showed no significant difference (p > 0.05). The diagnostic capability of STIR was significantly higher than those of other MR sequences (p < 0.05). Non-CE MR imaging was found to be as useful as MDCT for management of pulmonary nodules.

BACKGROUND AND PURPOSE: CT and MR angiographies have been reported to visualize the artery of Adamkiewicz (AKA) noninvasively to prevent spinal cord ischemia in surgery of thoracic descending aortic aneurysms. The purpose of this work was to compare the usefulness of CT angiography (CTA) with intra-arterial contrast injection (ACTA) with that of conventional CTA with intravenous contrast injection (IVCTA). MATERIALS AND METHODS: We enrolled 32 consecutive patients with thoracic or thoracoabdominal aortic aneurysms who were scheduled for surgical repair or endovascular stent-graft treatment. All of the CTA images were obtained using a 16-detector row CT scanner and 100 mL of contrast material (370 mg/mL) injected at a rate of 5 mL/s. Contrast was injected via the antecubital veins of 15 patients and via a pig-tail catheter placed at the proximal portion of the descending aorta in 17 patients who underwent IVCTA and IACTA, respectively. Two datasets were reconstructed from 2 consecutive scans. The AKA was identified as a characteristic hairpin curved vessel in the anterior midsagittal surface of the spine and by the absence of further enhancement in the second rather than in the first phase. Continuity between the AKA and aorta was confirmed when the vessel could be traced continuously by paging the oblique coronal multiplanar reconstruction or original axial images. RESULTS: Intra-arterial contrast injection was significantly more sensitive in identifying the AKA than IVCTA: 16 (94.1 %) of 17 versus 9 (60.0%) of 15 (P =.033). Continuity between the AKA and aorta through intercostal or lumbar artery was confirmed in 14 (87.5%) of 16 and 5 (55.6%) of 9 of the IACTA and IVCTA groups, respectively. CONCLUSION: Intra-arterial contrast injection detected the AKA at a high rate and verified continuity from the aorta to the AKA.

Purpose To evaluate a fully automatic computer-assisted diagnostic system for mild dementia with Lewy bodies (DLB), permitting distinction from mild Alzheimer's disease (AD). Methods Using F-18-fluorodeoxyglucose and positron emission tomography (FDG-PET), glucose metabolic images were obtained from mild DLB and mild AD patients. Two groups consisting of 16 mild DLB patients and 21 mild AD patients were recruited for diagnostic evaluation between mild DLB and mild AD. The mean age +/- SD of the mild DLB group and the mild AD group was 74.3 +/- 4.9 and 71.7 +/- 2.1 years, respectively, and the mean scores of the MMSE for the mild DLB and the mild AD group were 21.7 +/- 1.9 and 23.1 +/- 2.1, respectively. A receiver operating characteristic (ROC) analysis was performed to compare the diagnostic performance, in terms of discrimination between DLB and AD, of conventional axial FDG-PET images inspected visually by experts and beginners with that of our fully automatic diagnosis system using the statistical brain mapping method and Z scores obtained with the DLB template. Results The diagnostic performance of the automatic system was comparable to that of visual inspection by experts. The area under the ROC curve for the automatic diagnosis system was 0.77. The mean area under the ROC curve for visual inspection by experts and beginners was 0.76 and 0.65, respectively. Conclusion The fully automatic differential diagnosis system for distinction between mild DLB and AD showed a similar diagnostic accuracy to visual inspection by experts. It would be a useful diagnostic tool to distinguish mild DLB from mild AD in clinical practice.

The aim of this study was to investigate regional differences between morphologic and functional changes in patients with mild dementia with Lewy bodies (DLB) compared with those with Alzheimer's disease (AD). Methods: Twenty patients with very mild DLB (mean age, 74.5 y; mean Mini-Mental State Examination [MMSE] score, 24.0), 20 patients with very mild AD (mean age, 74.1 y; mean MMSE score, 24.0), and 20 age- and sex-matched healthy volunteers (normal controls [NC]) underwent both F-18-FDG PET and 3-dimensional spoiled gradient echo MRI. Fully automatic volumetry of the MRI data was used to obtain whole brain, hippocampal, occipital, and striatal volumes, which were compared with the results of a similar analysis of glucose metabolic data. Results: In DLB patients, volumetric data indicated a significant volume decrease in the striatum, whereas F-18-FDG PET showed significant glucose metabolic reductions in the temporal, parietal, and frontal areas-including in the occipital lobe-compared with those in the NC group. In contrast, in AD patients, both the hippocampal volume and glucose metabolism were significantly decreased, whereas the occipital volume and metabolism were preserved. Conclusion: Comparison of very mild DLB and AD revealed different morphologic and metabolic changes occurring in the medial temporal lobes and the occipital lobe, demonstrating characteristic pathophysiologic differences between these 2 diseases.

Objectives: To investigate the specific pattern of cerebral blood flow (CBF) in subjects with idiopathic normal pressure hydrocephalus (iNPH) using voxel-based analysis. Methods: N-isopropyl-p-[I-123]iodoamphetamine (IMP) single photon emission computed tomography (SPECT) images were performed in 30 iNPH patients, who met probable iNPH criteria, 30 Alzheimer disease (AD) patients and 15 normal control (NC) subjects. Inter-group comparisons between iNPH patients and NC subjects and between AD patients and NC subjects were performed using three-dimensional stereotactic surface projection (3D-SSP) analysis. Individual 3D-SSP images of the iNPH patients were assessed by visual inspection. Results: On the Z-score maps, areas of relative hypoperfusion were recognized around the corpus callosum in all 30 iNPH patients, as well as in the Sylvian fissure regions in 19 of 30 iNPH patients which included artifacts by dilated ventricles and the Sylvian fissures. Ten frontal dominant, eight parietotemporal dominant, and 12 diffuse hypoperfusion types were demonstrated. Inter-group comparison between iNPH and NC subjects showed relative hypoperfusion in the frontal and parietotemporal areas and severe hypoperfusion around the corpus callosum and Sylvian fissure regions, while parietotemporal and posterior cingulate CBF reduction was demonstrated between the AD and NC groups. Conclusion: Voxel-based analysis showed a characteristic pattern of regional CBF reduction with frontal dominant or diffuse cerebral hypoperfusion accompanying severe hypoperfusion around the corpus callosum and Sylvian fissures with artifacts.

We report successful stent implantation and secondary coil embolization in a wide-necked dissecting aneurysm in the vertebral artery. Intravascular ultrasonography (IVUS) showed the thrombosed pseudolumen clearly and enabled precise determination of the appropriate stent size. After stent implantation, Guglielmi detachable coil embolization was performed. Further experience is necessary to refine the technique, but IVUS may be useful to improve the safety of stent-assisted embolization. © 2006 Japan Radiological Society.

Purpose. The purpose of this study was to produce a fully automatic volumetric segmented brain image system (AVSIS) and to evaluate its utility for measuring hippocampal volumes and total intracranial volume (TIV). Materials and methods. We developed a combination technique comprising an anatomical standardization technique to measure TIV, whole brain volume (WBV), and hippocampal volume obtained by magnetic resonance (MR) imaging. Altogether, 15 healthy volunteers and 15 patients with Alzheimer's disease (AD) underwent three-dimensional spoiled gradient echo (3D-SPGR) imaging. Three measurements were performed by manual volumetry as the gold standard, a previous semiautomatic method, and our new method, AVSIS. Results. WBV and hippocampal volume in the AD group were significantly smaller than those in the healthy volunteer group measured by the semiautomatic method, manual method, and AVSIS. Each volume measured by AVSIS or semiautomatic method correlated with that measured by the manual method. The correlation coefficients between TIVs, WBVs, or hippocampal volumes measured by AVSIS and the manual method were 0.910, 0.902, and 0.918, respectively the correlation coefficients between TIVs, or WBVs, measured by the previous semiautomatic method and the manual method were 0.875, and 0.886, respectively. Conclusion. We developed a system for a fully automatic measurement of segmented brain structures and obtained good results. © Japan Radiological Society 2006.

We report computed tomography (CT) findings that demonstrated early disappearance of ectopic calcification in the bilateral posterior paraspinal muscles in a patient with rhabdomyolysis. A 37-year-old man with acute renal failure due to rhabdomyolysis caused by neuroleptic malignant syndrome underwent studies with CT and bone scintigraphy. First, bone scintigraphy showed high radiotracer uptake in bilateral posterior paraspinal muscles then CT demonstrated ectopic calcification in those muscles. After 2.5 months, CT showed that the calcification had completely disappeared. Bone scintigraphy anticipated calcification, and CT demonstrated a unique course of early disappearance of the calcification. © Japan Radiological Society 2006.

Purpose: The purpose of this study was to design a fully automatic computer-assisted diagnostic system for early- and late-onset mild Alzheimer's disease (AD). Methods: Glucose metabolic images were obtained from mild AD patients and normal controls using positron emission tomography (PET) and F-18-fluorodeoxyglucose (FDG). Two groups of 20 mild AD patients with different ages of onset were examined. A fully automatic diagnostic system using the statistical brain mapping method was established from the early-onset (EO) and late-onset (LO) groups, with mean ages of 59.1 and 70.9 years and mean MMSE scores of 23.3 and 22.8, respectively. Aged-matched normal subjects were used as controls. We compared the diagnostic performance of visual inspection of conventional axial FDG PET images by experts and beginners with that of our fully automatic diagnostic system in another 15 EO and 15 LO AD patients (mean age 58.4 and 71.7, mean MMSE 23.6 and 23.1, respectively) and 30 age-matched normal controls. A receiver operating characteristic (ROC) analysis was performed to compare data. Results: The diagnostic performance of the automatic diagnostic system was comparable with that of visual inspection by experts. The area under the ROC curve for the automatic diagnostic system was 0.967 for EO AD patients and 0.878 for LO AD patients. The mean area under the ROC curve for visual inspection by experts was 0.863 and 0.881 for the EO and LO AD patients, respectively. The mean area under the ROC curve for visual inspection by beginners was 0.828 and 0.717, respectively. Conclusion: The fully automatic diagnostic system for EO and LO AD was able to perform at a similar diagnostic level to visual inspection of conventional axial images by experts.

Purpose: The aim of this study was to investigate regional differences between morphologic and functional changes in the same patients with mild Alzheimer's disease (AD) using statistical parametric mapping (SPM) and voxel-based morphometry (VBM). Methods: Thirty patients with very mild AD (mean age 66.8 years, mean MMSE score 24.0) and 30 age- and sex-matched normal volunteers underwent both F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) and three-dimensional spoiled gradient echo (SPGR) magnetic resonance imaging (MRI). Statistical parametric mapping was used to conduct VBM analysis of the morphological data, which were compared voxel by voxel with the results of a similar analysis of the glucose metabolic data. Results: In AD patients, VBM data indicated a significant gray matter volume density decrease in bilateral amygdala/hippocampus complex (p < 0.05, corrected), while FDG-PET analysis showed significant glucose metabolic reductions in the posterior cingulate gyri and the right parietal lobule, compared with those in the normal control group. Conclusion: In very mild AD, morphological change occurs in the medial temporal lobes, while in contrast, metabolic changes occur in the posterior cingulate gyri and parietal lobule.

BACKGROUND AND PURPOSE: Voxel-based morphometry (VBM), used for detecting brain atrophy, permits comparison of local gray matter concentration at every voxel in an image between two groups. We sought to delineate the specific patterns of cerebral gray matter loss with regard to onset of Alzheimer's disease (AD) by using MR imaging and VBM and to evaluate the diagnostic performance of VBM with Z score images. METHODS: Two groups of 30 patients with mild AD of different ages of onset were examined. Mean ages in the early- and late-onset groups were 60.2 +/- 5.2 and 71.5 +/- 2.6 years, respectively. Control subjects were aged-matched healthy volunteers. Regions of gray matter loss in early- and late-onset AD were examined with VBM. Diagnostic performance of Z score images obtained with the VBM method was evaluated in patients and control subjects by calculating the area under the receiver operating characteristic curve (A(z)). RESULTS: Both AD groups had significantly reduced gray matter in the bilateral medial temporal regions. In addition, the early-onset group had more severe gray matter loss in the bilateral parietal and posterior cingulate cortices and precuneus region. No difference was noted in diagnostic performance of Z score images between the early- (A(z) = 0.9435) and late-onset (A(z) = 0.9018) groups. CONCLUSION. Differences were noted in the patterns of regional gray matter loss in patients with early-onset AD versus those with late-onset AD. Parietotemporal and posterior cingulate gray matter loss was found in early-onset AD but not in late-onset AD. Z score images obtained with VBM had a great diagnostic performance for mild AD and can be applied for detecting mild AD in clinical examinations.

後腹膜転移を契機に発見された後腹膜腫瘍の1例を報告

腫瘍性骨軟化症のMRI, CT, PET像などを解説

近年，CT装置の発展に伴い，従来法であるフィルター逆投影（FBP法）より低被曝で撮像できる，逐次近似法（IR法）を用いた冠動脈CT検査が臨床に導入されてきた．しかし，患者の臨床転帰に対する影響については，撮像法を比較検討したデータが不足している． 本研究は，IR法がFBP法と比較して，患者の短期臨床転帰を有意に変えることがないことを明らかにするための，国内多施設が参加する無作為化比較試験である．本研究により「IR法は，患者の短期臨床転帰を変えることなく，冠動脈CTの低被曝化を可能である」ことを示し，低被曝CT検査の標準化を図ることができる． 本研究では狭心症患者を対象とし，従来の方法であるフィルター逆投影法を用いた冠動脈CT検査と比べた場合の，逐次近似再構成法を応用した低被曝冠動脈CT検査について，以下の2 点を国内多施設で前向きに評価する． 1．登録から90 日内に，侵襲的カテーテル検査(ICA; invasive coronary angiography)を行い，有意な狭窄病変を認めなかった患者の割合を主要評価項目とし，低被曝冠動脈CTの診療への影響を評価すること． 2．逐次近似再構成法を応用した低被曝冠動脈CT検査が画像解析法に与える影響について，臨床的に有益な情報を発信すること． 2020年度は，本研究の倫理委員会承認を取得し，患者登録の準備を行った．しかしCOVID-19の蔓延に伴い，患者登録を行うことが出来なかった．

The present study using clinical images has shown that our proposed noise-reduction method is compatible with image quality improvement with substantial noise reduction and security of quantitative parameters obtained from the CT examination. Further, we could maintain the image quality as well as the radiation dose reduction and the contrast agent amount reduction using this noise-reduction method. However, there is a limitation in this noise-reduction method that a sufficient effect can not be obtained in terms of heart rate and arrhythmia at the time of CT examination.

Assessment of muscle blood flow response (MFR) by dynamic muscle blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging is unknown. First, we developed the method to assess BOLD effect in the muscle by using 3 tesla MR and performed its validation with a new developed in-house software. Second, we investigated the effect of smoking on vascular function according to MFR during postocclusive reactive hyperemia in young smokers and nonsmokers. We underwent BOLD imaging in sixteen healthy male volunteers. The 2 key mBOLD variables such as times to half hyperemic peak (T1/2peak) and times to peak (TTP) were evaluated. This study showed that T1/2peak and TTP were significantly longer in smokers in reactive hyperemia. Dynamic BOLD MR imaging of calf muscle during postocclusive reactive hyperemia demonstrated statistically significant differences in T1/2peak and TTP between young smokers and nonsmokers, indicating the presence of early stage smoking-related deterioration in MFR.

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