Yasutoshi Ohta's research while affiliated with National Cerebral and Cardiovascular Center and other places

Purpose This study examines the hepatic extracellular volume fraction (ECV) disparity between the left and right lobes (ECV_left and ECV_right) in patients with chronic thromboembolic pulmonary hypertension (CTEPH), its association with right heart catheterization (RHC) metrics, and with intolerance to increased pulmonary hypertension (PH)-targeted medication dosages. Methods We retrospectively analyzed 72 CTEPH-diagnosed patients who underwent equilibrium-phase abdominal dual-energy CT (DECT) and RHC. Hepatic ECVs, derived from DECT’s iodine maps using circular regions of interest in the liver and aorta, were correlated with RHC parameters via Spearman’s rank correlation and lobe differences through the Wilcoxon signed-rank test. Logistic regression assessed cases with ECV_left exceeding ECV_right by > 0.05, while receiver operating characteristic curve analysis gauged ECVs’ predictive power for medication intolerance. Results Of the 72 patients (57 females; median age 69), ECV_total (0.24, IQR 0.20–0.27) moderately correlated with RHC parameters (rs = 0.28, −0.24, 0.3 for mean pulmonary arterial pressure, cardiac index [CI], and pulmonary vascular resistance index, respectively). ECV_left significantly surpassed ECV_right (0.25 vs. 0.22, p < 0.001), with a greater ECV_left by > 0.05 indicating notably lower CI (p < 0.001). In 27 patients on PH medication, ECV_left effectively predicted medication intolerance (AUC = 0.84). Conclusion In CTEPH patients, hepatic ECV correlated with RHC metrics, where elevated left lobe ECV suggested reduced CI and potential medication intolerance. Graphical Abstract The hepatic extracellular volume fraction (ECV), measured via dual-energy CT, was notably higher in the left lobe compared to the right in patients with chronic thromboembolic pulmonary hypertension, with elevated ECV in the left lobe correlating with reduced cardiac index and intolerance to medication.

Introduction: Liver fibrosis is associated with heart failure and left ventricular diastolic dysfunction. The fibrosis 4 (FIB-4) index is calculated from transaminases, age, and platelet count and can be used to screen patients with liver fibrosis. The myocardial extracellular volume fraction (ECVf) can be evaluated using contrast-enhanced cardiac magnetic resonance imaging (CMR). Hypothesis: ECVf is increased in patients with high FIB-4 index. AIMS: This study aimed to clarify the association between FIB-4 index and ECVf. Methods: A retrospective analysis was performed on patients aged ≥ 45 years with left ventricular ejection fraction (LVEF) > 40 % who underwent CMR at two Japanese institutions. Patients were divided into 3 groups according to the FIB-4 index: Low: FIB-4 index < 1.3; Intermediate: 1.3 ≤ FIB-4 index < 2.67; High: 2.67 ≤ FIB-4 index. The association between the FIB-4 index and ECVf was evaluated using multiple regression analysis, with the FIB-4 index treated as a continuous and nominal variable. Results: A total of 244 patients were included in the analysis, 136 of whom underwent contrast-enhanced CMR and could be evaluated for ECVf. The ECVf of the high FIB-4 index group was significantly higher than that of the other two groups (High: 31.0 ± 4.3 %; Intermediate: 27.9 ± 3.4 %; Low: 27.6 ± 3.7 %. High vs. Intermediate, p = 0.014; High vs. Low, p = 0.008; Intermediate vs. Low, p = 0.65). Multivariate analysis showed that both the FIB-4 index (continuous variable) and high FIB-4 index (nominal variable) were associated with higher ECVf (continuous variable, p = 0.043; nominal variable, p = 0.016). Conclusions: The high FIB-4 index was independently associated with increased ECVf. In contrast, patients with the intermediate FIB-4 index did not have increased ECVf. These suggested the usefulness of FIB-4 index as a cardiac fibrotic parameter.

Backgrounds: The lung-to-heart ratio (L/H ratio) in myocardial perfusion scintigraphy (MPS) is a useful marker that complements the sensitivity of ischemia detection. However, it requires planar imaging acquired following a separate protocol in addition to single-photon emission computed tomography (SPECT). We developed a novel method for constructing virtual planar image (VPI) from SPECT data. Methods: Myocardial phantoms using Tl-201 were built with different amounts of radioactivity in the lungs. SPECT data and conventional planar images of these phantoms were collected with an Anger-type gamma camera. VPIs were constructed by adding all coronal images reconstructed from SPECT data. The clinical utility of VPIs obtained from 52 patients who underwent MPS with Tc-99m sestamibi was evaluated. Results: The radioactivity linearity of VPIs was satisfactory, with a correlation coefficient of r ≥ .99 between the measured amounts of radioactivity and image counts. The L/H ratios obtained from VPI analysis were strongly correlated with those of conventional planar images with a correlation coefficient of r ≥ .99 in the phantom study and r = .929 in clinical application. Conclusion: The accuracy of VPI-based L/H ratio analysis was comparable to that of conventional planar image-based analysis. VPIs could be used as an alternative method of obtaining planar images in clinical settings.

Rationale and objectives: Coronary inflammation related to high-risk hemorrhagic plaques can be captured by the perivascular fat attenuation index (FAI) using coronary computed tomography angiography (CCTA). Since the FAI is susceptible to image noise, we believe deep learning (DL)-based post hoc noise reduction can improve diagnostic capability. We aimed to assess the diagnostic performance of the FAI in DL-based denoised high-fidelity CCTA images compared with coronary plaque magnetic resonance imaging (MRI) delivered high-intensity hemorrhagic plaques (HIPs). Materials and methods: We retrospectively reviewed 43 patients who underwent CCTA and coronary plaque MRI. We generated high-fidelity CCTA images by denoising the standard CCTA images using a residual dense network that supervised the denoising task by averaging three cardiac phases with nonrigid registration. We measured the FAIs as the mean CT value of all voxels (range of -190 to -30 HU) located within a radial distance from the outer proximal right coronary artery wall. The diagnostic reference standard was defined as HIPs (high-risk hemorrhagic plaques) using MRI. The diagnostic performance of the FAI in the original and denoised images was assessed using receiver operating characteristic curves. Results: Of 43 patients, 13 had HIPs. The denoised CCTA improved the area under the curve (0.89 [95% confidence interval (CI) 0.78-0.99]) of the FAI compared with that in the original image (0.77 [95% CI, 0.62-0.91], p = 0.008). The optimal cutoff value for predicting HIPs in denoised CCTA was -69 HU with 0.85 (11/13) sensitivity, 0.79 (25/30) specificity, and 0.80 (36/43) accuracy. Conclusion: DL-based denoised high-fidelity CCTA improved the AUC and specificity of the FAI for predicting HIPs.

Objectives To determine the optimal inversion time (TI) from Look-Locker scout images using a convolutional neural network (CNN) and to investigate the feasibility of correcting TI using a smartphone.Methods In this retrospective study, TI-scout images were extracted using a Look-Locker approach from 1113 consecutive cardiac MR examinations performed between 2017 and 2020 with myocardial late gadolinium enhancement. Reference TI null points were independently determined visually by an experienced radiologist and an experienced cardiologist, and quantitatively measured. A CNN was developed to evaluate deviation of TI from the null point and then implemented in PC and smartphone applications. Images on 4 K or 3-megapixel monitors were captured by a smartphone, and CNN performance on each monitor was determined. Optimal, undercorrection, and overcorrection rates using deep learning on the PC and smartphone were calculated. For patient analysis, TI category differences in pre- and post-correction were evaluated using the TI null point used in late gadolinium enhancement imaging.ResultsFor PC, 96.4% (772/749) of images were classified as optimal, with under- and overcorrection rates of 1.2% (9/749) and 2.4% (18/749), respectively. For 4 K images, 93.5% (700/749) of images were classified as optimal, with under- and overcorrection rates of 3.9% (29/749) and 2.7% (20/749), respectively. For 3-megapixel images, 89.6% (671/749) of images were classified as optimal, with under- and overcorrection rates of 3.3% (25/749) and 7.0% (53/749), respectively. On patient-based evaluations, subjects classified as within optimal range increased from 72.0% (77/107) to 91.6% (98/107) using the CNN.Conclusions Optimizing TI on Look-Locker images was feasible using deep learning and a smartphone.Key Points • A deep learning model corrected TI-scout images to within optimal null point for LGE imaging. • By capturing the TI-scout image on the monitor with a smartphone, the deviation of the TI from the null point can be immediately determined. • Using this model, TI null points can be set to the same degree as that by an experienced radiological technologist.

Background To assess low-contrast areas such as plaque and coronary artery stenosis, coronary computed tomography angiography (CCTA) needs to provide images with lower noise without increasing radiation doses. Purpose To develop a deep learning-based noise-reduction method for CCTA using four-dimensional noise reduction (4DNR) as the ground truth for supervised learning. Material and Methods \We retrospectively collected 100 retrospective ECG-gated CCTAs. We created 4DNR images using non-rigid registration and weighted averaging three timeline CCTA volumetric data with intervals of 50 ms in the mid-diastolic phase. Our method set the original reconstructed image as the input and the 4DNR as the target image and obtained the noise-reduced image via residual learning. We evaluated the objective image quality of the original and deep learning-based noise-reduction (DLNR) images based on the image noise of the aorta and the contrast-to-noise ratio (CNR) of the coronary arteries. Further, a board-certified radiologist evaluated the blurring of several heart structures using a 5-point Likert scale subjectively and assigned a coronary artery disease reporting and data system (CAD-RADS) category independently. Results DLNR CCTAs showed 64.5% lower image noise ( P < 0.001) and achieved a 2.9 times higher CNR of coronary arteries than that in original images, without significant blurring in subjective comparison ( P > 0.1). The intra-observer agreement of CAD-RADS in the DLNR image was excellent (0.87, 95% confidence interval = 0.77–0.99) with original CCTAs. Conclusion Our DLNR method supervised by 4DNR significantly reduced the image noise of CCTAs without affecting the assessment of coronary stenosis.

Purpose: To evaluate the image quality of high-spatial-resolution two-dimensional (2D) late gadolinium enhancement (LGE) cardiac MRI compared with conventional normal-resolution LGE MRI. Materials and methods: This prospective study included participants suspected of having cardiomyopathy who underwent cardiac MRI between March 2021 and December 2021. Normal-resolution and high-resolution 2D LGE sequences (inversion recovery [IR] and phase-sensitive inversion recovery [PSIR]) were performed at 3 T. Resolution was compared between normal-resolution and high-resolution images obtained in a quality assurance phantom. In vivo image quality and resolution were evaluated qualitatively using a five-point scoring system. Receiver operating characteristic curve analysis was used for LGE detection performance. Border sharpness was assessed with profile curve measurement. The contrast-to-noise ratio (CNR) between hyperenhancement and remote myocardium and LGE detection performance were calculated using normal-resolution IR images as the reference. Results: In total, 120 participants were evaluated (mean age, 56 years ± 17 [SD]; 72 men). Features smaller than 1 mm were detectable only on high-resolution images of the phantom. In vivo, the image resolution score with high-resolution LGE was 4.14-4.24, which was higher than the normal-resolution LGE reference score of 2.99 (P < .05). Border sharpness was higher in high-resolution images (P < .001). Receiver operating characteristic curve analysis revealed no evidence of a difference in LGE detection between normal-resolution and high-resolution images. There was also no evidence of a change in CNR of LGE in IR and PSIR magnitude compared with reference images. Conclusion: Comparison of image quality in 2D high-resolution and normal-resolution LGE cardiac MRI demonstrated the highest resolution for high-resolution IR and high-resolution PSIR magnitude sequences.Keywords: Cartilage Imaging, MRI, Cardiac, Heart, Imaging Sequences, Comparative Studies Supplemental material is available for this article. © RSNA, 2022.

Background: Although catheter ablation (CA) has become a standard therapeutic approach to atrial fibrillation (AF), it imposes a low but relevant risk of thromboembolic complications of around 0.5%-1%, including ischemic strokes, and has an additional risk of clinically silent cerebral embolisms (SCEs) of 10%-40%. Both cryoballoon (CB) and radiofrequency (RF) ablation are routinely used clinically worldwide, yet there are few prospective data comparing the incidence of cerebral embolism after CA of AF between CB and RF ablation. Methods: The aim of the Embo-Abl study will be to compare the incidence of cerebral embolisms on 3 T diffusion-weighted image magnetic resonance imaging (MRI) after CA of AF between CB and RF ablation in patients with AF in a prospective, multicenter, open-label, controlled, randomized fashion. The primary endpoint of the Embo-Abl study will be the occurrence of MRI-detected SCE 1-3 days after CA. The patients will be registered and randomly assigned to either the CB or RF ablation group in a 1:1 ratio. The study cohort will include 230 patients with AF from a multicenter in Japan. Results: The results of this study are currently under investigation. Conclusion: The Embo-Abl study will be the first to compare the incidence of periprocedural cerebral embolisms caused by CA of AF between CB and RF ablation in a prospective, multicenter, randomized, controlled fashion.