Dual-Energy CTを用いた肺血液量画像の定量的評価：急性肺血栓塞栓症患者に対する定量的重症度評価

BACKGROUND:Regional iodine distribution assessment on dual-energy computed tomography (DECT) has been suggested as useful for management of acute pulmonary thromboembolism (APTE) patients. However, no reported studies have made a direct comparison between quantitatively assessed DECT and right-to-left ventricular (RV/LV) ratio on CT for differentiation of right heart dysfunction (RHD) from non-right heart dysfunction (NRHD) in APTE patients. PURPOSE:To determine the capability of DECT for differentiation of RHD from NRHD in APTE patients. MATERIAL AND METHODS:Thirteen APTE patients underwent DECT and echocardiography at onset of APTE. Patients were divided into RHD (n = 7) and NRHD (n = 6) groups based on echocardiography. A normalized lung perfused blood volume map was generated, and two kinds of overall perfusion (OP) index were determined, one placed over each lung field (OP index A) and as the average from six regions of interest (ROIs) placed over each lung field (OP index B). The heterogeneity index was also determined as the standard deviation for the six ROIs. RV/LV ratio evaluations were also performed. To assess differences between the two groups, each index was statistically compared with the Mann-Whitney U test. The receiver-operating curve-based positive test was then performed to determine the feasible threshold value for dividing patients into the two groups. Finally, differentiation capabilities of the indexes were compared using McNemar's test. RESULTS:Significant differences between the two groups were found for both OP indexes and RV/LV ratio (P < 0.05). For each of the feasible threshold values, accuracy of each OP index with and without RV/LV ratio was better than that of the RV/LV ratio. CONCLUSION:Quantitative DECT has good potential for differentiation of APTE patients with and without right heart dysfunction.博士（医学）・乙第1350号・平成26年12月3日© The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav

Clinical Analysis of 110 Postoperative Deaths of the Patients with Permanent Implantable Pacemaker

During 14 years follow up of 754 patients received permanent cardiac pacemaker (PM) implantation, 110 cases have died. In this paper, the cause of death of them was clinically analyzed. The death to senility was most frequent, in 31 cases out of 110 deaths (28.2%), and then heart failure in 19 cases (17.3%), cerebrovascular disease in 16 cases (14.5%), sudden death in 14 cases (12.7%), malignancy in 7 cases (6.4%), acute myocardial infarction in 7 cases (6.4%), severe infectious disease in 4 cases (3.6%), unknown etiology in 4 cases (3.6%), renal failure and Disseminated Intravascular Coagulation Syndrome (DIC) in 2 cases (1.8%), respectively, suicide in one case (0.9%). Cause of death by underlying disease was rather characteristic. Senility was frequent in the patients with atrioventricular (A-V) block (38.5%), while cerebrovascular disease was highly observed in the patients with Sick Sinus Syndrome (SSS) (28.1%), and heart failure was highly observed in the patients with atrial fibrillation (46.2%). Senility was seen in 44.8% of the patients with coronary arteriosclerosis, cardiac death in 85. 7% of the patients with cardiomyopathy, and in 100.0% of the cases with valvular disease. The above mentioned fact suggests that cardiovascular check up is most important in postoperative follow up of the patients with PM. In old cases, senility and infection were major cause of death, so guidance concerning to dietary life and periodical health examination against wasting disease is important especially in this group. And, active care for heart failure is also more important in the patients with cardiomyopathy and valvular disease

Deep learning reconstruction for brain diffusion-weighted imaging: efficacy for image quality improvement, apparent diffusion coefficient assessment, and intravoxel incoherent motion evaluation in in vitro and in vivo studies

PURPOSEDeep learning reconstruction (DLR) to improve imaging quality has already been introduced, but no studies have evaluated the effect of DLR on diffusion-weighted imaging (DWI) or intravoxel incoherent motion (IVIM) in in vitro or in vivo studies. The purpose of this study was to determine the effect of DLR for magnetic resonance imaging (MRI) in terms of image quality improvement, apparent diffusion coefficient (ADC) assessment, and IVIM index evaluation on DWI through in vitro and in vivo studies.METHODSFor the in vitro study, a phantom recommended by the Quantitative Imaging Biomarkers Alliance was scanned and reconstructed with and without DLR, and 15 patients with brain tumors with normal-appearing gray and white matter examined using IVIM and reconstructed with and without DLR were included in the in vivo study. The ADCs of all phantoms for DWI with and without DLR, as well as the coefficient of variation percentage (CV%), and ADCs and IVIM indexes for each participant, were evaluated based on DWI with and without DLR by means of region-of-interest measurements. For the in vitro study, using the mean ADCs for all phantoms, a t-test was adopted to compare DWI with and without DLR. For the in vivo study, a Wilcoxon signed-rank test was used to compare the CV% between the two types of DWI. In addition, the Wilcoxon signed-rank test was used to compare the ADC, true diffusion coefficient (D), pseudodiffusion coefficient (D*), and percentage of water molecules in micro perfusion within 1 voxel (f) with and without DLR; the limits of agreement of each parameter were determined through a Bland–Altman analysis.RESULTSThe in vitro study identified no significant differences between the ADC values for DWI with and without DLR (P > 0.05), and the CV% was significantly different for DWI with and without DLR (P < 0.05) when b values ≥250 s/mm2 were used. The in vivo study revealed that D* and f with and without DLR were significantly different (P < 0.001). The limits of agreement of the ADC, D, and D* values for DWI with and without DLR were determined as 0.00 ± 0.51 × 10-3, 0.00 ± 0.06 × 10-3, and 1.13 ± 4.04 × 10-3 mm2/s, respectively. The limits of agreement of the f values for DWI with and without DLR were determined as −0.01 ± 0.07.CONCLUSIONDeep learning reconstruction for MRI has the potential to significantly improve DWI quality at higher b values. It has some effect on D* and f values in the IVIM index evaluation, but ADC and D values are less affected by DLR

Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications

Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases

Measurement Variability in Treatment Response Determination for Non-Small Cell Lung Cancer: Improvements using Radiomics

Multimodality imaging measurements of treatment response are critical for clinical practice, oncology trials, and the evaluation of new treatment modalities. The current standard for determining treatment response in non-small cell lung cancer (NSCLC) is based on tumor size using the RECIST criteria. Molecular targeted agents and immunotherapies often cause morphological change without reduction of tumor size. Therefore, it is difficult to evaluate therapeutic response by conventional methods. Radiomics is the study of cancer imaging features that are extracted using machine learning and other semantic features. This method can provide comprehensive information on tumor phenotypes and can be used to assess therapeutic response in this new age of immunotherapy. Delta radiomics, which evaluates the longitudinal changes in radiomics features, shows potential in gauging treatment response in NSCLC. It is well known that quantitative measurement methods may be subject to substantial variability due to differences in technical factors and require standardization. In this review, we describe measurement variability in the evaluation of NSCLC and the emerging role of radiomics. © 2019 Wolters Kluwer Health, Inc. All rights reserved

Pulmonary MR angiography and perfusion imaging—A review of methods and applications

The pulmonary vasculature and its role in perfusion and gas exchange is an important consideration in many conditions of the lung and heart. Currently the mainstay of imaging of the vasculature and perfusion of the lungs lies with CT and nuclear medicine perfusion scans, both of which require ionizing radiation exposure. Improvements in MRI techniques have increased the use of MRI in pulmonary vascular imaging. Here we review MRI methods for imaging the pulmonary vasculature and pulmonary perfusion, both using contrast enhanced and non-contrast enhanced methodology. In many centres pulmonary MR angiography and dynamic contrast enhanced perfusion MRI are now well established in the routine workflow of patients particularly with pulmonary hypertension and thromboembolic disease. However, these imaging modalities offer exciting new directions for future research and clinical use in other respiratory diseases where consideration of pulmonary perfusion and gas exchange can provide insight in to pathophysiology