Publications by authors named "Osamu Abe"

342 Publications

Using modulated and smoothed data improves detectability of volume difference in group comparison, but reduces accuracy with atlas-based volumetry using Statistical Parametric Mapping 12 software.

Acta Radiol 2021 Jul 19:2841851211032442. Epub 2021 Jul 19.

Department of Radiological Technology, Faculty of Health Science, 12847Juntendo University, Juntendo University, Tokyo, Japan.

Background: Atlas-based volumetry using three-dimensional T1-weighted (3D-T1W) magnetic resonance imaging (MRI) has been used previously to evaluate the volumes of intracranial tissues.

Purpose: To evaluate the detectability of volume difference and accuracy for volumetry using smoothed data with an atlas-based method.

Material And Methods: Twenty healthy individuals and 24 patients with idiopathic normal-pressure hydrocephalus (iNPH) underwent 3-T MRI, and sagittal 3D-T1W images were obtained in all participants. Signal values (as tissue probability) of voxels in five segmented data types (gray matter, white matter, cerebrospinal fluid [CSF], skull, soft tissue) derived from the 3D-T1W images with SPM 12 software were assigned simulated 3D-T1W signal intensities to each tissue image. The assigned data were termed "reference data." We created a reference 3D-T1W image that included the reference data of all five tissue types. Standard volumes were measured for the reference CSF data with region of interest of lateral ventricle in native space, and measured volumes were obtained for non-smoothed and smoothed-modulated data. Detectability was evaluated between measured volumes in the healthy control and iNPH groups. Accuracy was evaluated as the difference between the mean measured and standard volumes.

Results: In group comparison of measured volumes between the healthy control and iNPH groups, the lowest value was for smoothed-modulated CSF data. In both groups, the largest difference from the standard volume was found for the mean of the measured volumes for smoothed-modulated CSF data.

Conclusion: Our study shows that using smoothed data can improve detectability in group comparison. However, using smoothed data reduces the accuracy of volumetry.
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http://dx.doi.org/10.1177/02841851211032442DOI Listing
July 2021

Physiological 2-deoxy-2-[fluorine-18] fluoro-D-glucose accumulation in the thenar eminence in adults: a single-center retrospective study.

Ann Nucl Med 2021 Jul 16. Epub 2021 Jul 16.

Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Objective: This study evaluated the frequency, and effect of physiological 2-deoxy-2-[fluorine-18] fluoro-D-glucose (FDG) tracer injection and its association with the penetration rates of mobile devices.

Methods: This retrospective analysis included 213 patients (mean age ± standard deviation, 66.2 ± 14.1 years; range 23-93 years; 125 men) who underwent FDG-positron emission tomography examination. Elevated FDG activity in the thenar eminence with maximum standardized uptake value (SUVmax) ≥ 2.5 was considered positive. Differences according to age, sex, laterality, and tracer injection side were evaluated using Fisher's exact test. Associations were assessed using Pearson's correlation coefficient.

Results: Twenty-three percent (49/213) of the patients had elevated FDG activity in the thenar eminence (mean SUVmax, 3.50 ± 1.04; range 2.5-6.3), including 18 with bilateral findings. No significant difference existed according to age (< 50 years vs. 50-69 years vs. ≥ 70 years), sex, laterality, or tracer injection side. No significant correlation existed between penetration rates of mobile devices and the findings (p = 0.08).

Conclusion: Elevated FDG activity in the thenar eminence occurs in adults, regardless of age, sex, laterality, or tracer injection side. This should be considered a common physiological change that does not warrant any further investigation.
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http://dx.doi.org/10.1007/s12149-021-01654-zDOI Listing
July 2021

Arterial Transit Time-Based Multidelay Combination Strategy Improves Arterial Spin Labeling Cerebral Blood Flow Measurement Accuracy in Severe Steno-Occlusive Diseases.

J Magn Reson Imaging 2021 Jul 15. Epub 2021 Jul 15.

Department of Neurosurgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.

Background: Although perfusion imaging plays a key role in the management of steno-occlusive diseases, the clinical usefulness of arterial spin labeling (ASL) is limited by technical issues.

Purpose: To examine the effect of arterial transit time (ATT) prolongation on cerebral blood flow (CBF) measurement accuracy and identify the best CBF measurement protocol for steno-occlusive diseases.

Study Type: Prospective.

Population: Moyamoya (n = 10) and atherosclerotic diseases (n = 8).

Field Strength/sequence: A 3.0T/3DT -weighted and ASL.

Assessment: Hadamard-encoded multidelay ASL scans with/without vessel suppression (VS) and single-delay ASL scans with long-label duration (LD) and long postlabeling delay (PLD), referred to as long-label long-delay (LLLD), were acquired. CBF measurement accuracy and its ATT dependency, measured as the correlation between the relative CBF measurement difference (ASL-single-photon emission computed tomography [SPECT]) and ATT, were compared among 1) Combo (incorporating multidelay and LLLD data based on ATT), 2) standard (LD/PLD = 1333/2333 msec), and 3) LLLD (LD/PLD = 4000/4000 msec) protocols, using whole-brain voxel-wise correlation with reference standard SPECT CBF. The effect of VS on CBF measurement accuracy was also assessed.

Statistical Tests: Pearson's correlation coefficient, repeated-measures analysis of variance, t-test. P< 0.05 was considered significant.

Results: Pearson's correlation coefficients between ASL and SPECT CBF measurements were as follows: Combo = 0.55 ± 0.09; standard = 0.52 ± 0.12; LLLD = 0.41 ± 0.10. CBF measurement was least accurate in LLLD and most accurate in Combo. VS significantly improved overall CBF measurement accuracy in the standard protocol and in moyamoya patients for the Combo. ATT dependency analysis revealed that, compared with Combo, the standard and LLLD protocols showed significantly lower and negative and significantly higher and positive correlations, respectively (standard = -0.12 ± 0.04, Combo = -0.04 ± 0.03, LLLD = 0.17 ± 0.03).

Data Conclusion: By using ATT-corrected CBF derived from LD/PLD = 1333/2333 msec as a base and by compensating underestimation in delayed regions using multidelay scans, the ATT-based Combo strategy improves CBF measurement accuracy compared with single-delay protocols in severe steno-occlusive diseases.

Evidence Level: 1 TECHNICAL EFFICACY: Stage 2.
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http://dx.doi.org/10.1002/jmri.27823DOI Listing
July 2021

Delayed cerebral enhancement on post-mortem computed tomography due to residual contrast medium administered shortly before death.

Radiol Case Rep 2021 Aug 8;16(8):2056-2060. Epub 2021 Jun 8.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.

Postmortem computed tomography (CT) is currently a well-known procedure and helps in postmortem investigations. In this case report, we report a unique postmortem CT finding: delayed cerebral enhancement associated with the antemortem infusion of contrast medium. A 72-year-old female lost consciousness at a restaurant and was taken to a hospital in an ambulance. Despite resuscitation efforts, she died of hypoxic-ischemic encephalopathy caused by cardiac arrest. About 6 h before her death, she underwent enhanced antemortem CT of the head. No abnormal enhancement was observed in the cerebral parenchyma. Then, 11 h after her death, she underwent unenhanced postmortem CT, which showed bilateral hyperdense caudate nucleus and putamina, due to residual iodinated contrast medium, in addition to other characteristic findings of hypoxic-ischemic encephalopathy. The mechanism underlying this phenomenon could be the destruction of the blood-brain barrier, and/or selective vulnerability, due to hypoxic-ischemic changes in the gray matter. Enhancement of basal ganglia on postmortem CT due to antemortem infusion of iodinated contrast medium might suggest hypoxic-ischemic encephalopathy, which should be noted in postmortem CT interpretations.
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http://dx.doi.org/10.1016/j.radcr.2021.04.065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8203565PMC
August 2021

Longitudinal stability of resting-state networks in normal aging, mild cognitive impairment, and Alzheimer's disease.

Magn Reson Imaging 2021 Oct 19;82:55-73. Epub 2021 Jun 19.

Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.

Test-retest reliability is essential for using resting-state functional magnetic resonance imaging (rs-fMRI) as a potential biomarker for Alzheimer's disease (AD), especially when monitoring longitudinal changes and treatment effects. In addition, test-retest variability itself might represent a feature of AD. Using 3.0 T rs-fMRI data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, we examined the long-term (1-year) test-retest reliability of resting-state networks (RSNs) in 31 healthy elderly subjects, 63 patients with mild cognitive impairment (MCI), and 17 patients with AD by applying temporal concatenation group independent component analysis and dual regression. The intraclass correlation coefficient estimates of RSN amplitudes ranged from 0.44 to 0.77 in healthy elderly subjects, from 0.31 to 0.62 in patients with MCI, and from -0.06 to 0.44 in patients with AD. The overall test-retest reliability of RSNs was lower in patients with MCI than in healthy elderly subjects, and was lower in patients with AD than in patients with MCI. The differences in the test-retest reliabilities were due to the RSN amplitudes rather than the RSN shapes. Head motion was not significantly different among the three groups of subjects. The results indicate that the test-retest stability of RSNs generally declines with progression to MCI and AD, mainly due to the RSN amplitudes rather than the RSN shapes. The test-retest instability in MCI and AD may reflect progressive neurofunctional alterations related to the pathology of AD.
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http://dx.doi.org/10.1016/j.mri.2021.06.020DOI Listing
October 2021

Structural connectivity changes in the cerebral pain matrix in burning mouth syndrome: a multi-shell, multi-tissue-constrained spherical deconvolution model analysis.

Neuroradiology 2021 Jun 18. Epub 2021 Jun 18.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.

Purpose: Burning mouth syndrome (BMS) is a chronic intraoral pain syndrome. Previous studies have attempted to determine the brain connectivity features in BMS using functional and structural magnetic resonance imaging. However, no study has investigated the structural connectivity using multi-shell, multi-tissue-constrained spherical deconvolution (MSMT-CSD), anatomically constrained tractography (ACT), and spherical deconvolution informed filtering of tractograms (SIFT). Therefore, this study aimed to assess the differences in brain structural connectivity of patients with BMS and healthy controls using probabilistic tractography with these methods, and graph analysis.

Methods: Fourteen patients with BMS and 11 age- and sex-matched healthy volunteers underwent 3-T magnetic resonance imaging. MSMT-CSD-based probabilistic structural connectivity was computed using the second-order integration over fiber orientation distributions algorithm based on nodes set in 84 anatomical cortical regions with ACT and SIFT. A t-test was performed for comparisons between the BMS and healthy control brain networks.

Results: The betweenness centrality was significantly higher in the left insula, right amygdala, and right lateral orbitofrontal cortex and significantly lower in the right inferotemporal cortex in the BMS group than that in healthy controls. However, no significant difference was found in the clustering coefficient, node degree, and small-worldness between the two groups.

Conclusion: Graph analysis of brain probabilistic structural connectivity, based on diffusion imaging using an MSMT-CSD model with ACT and SIFT, revealed alterations in the regions comprising the pain matrix and medial pain ascending pathway. These results highlight the emotional-affective profile of BMS, which is a type of chronic pain syndrome.
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http://dx.doi.org/10.1007/s00234-021-02732-9DOI Listing
June 2021

Tumor size in patients with severe pulmonary emphysema might be underestimated on preoperative CT.

Eur Radiol 2021 Jun 16. Epub 2021 Jun 16.

Department of Diagnostic Radiology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan.

Objectives: To evaluate the effect of emphysema on tumor diameter measured on preoperative computed tomography (CT) images versus pathological specimens.

Materials And Methods: We investigated patients who underwent primary lung cancer surgery: 55 patients (57 tumors) with severe emphysema and 57 patients (57 tumors) without emphysema. The tumor diameters measured in the postoperative pathological specimens were compared with those measured on the axial CT images and on multiplanar reconstruction (MPR) CT images by two independent radiologists; a subgroup analysis according to tumor size was also performed. A paired or unpaired t test was performed, depending on the tested subjects.

Results: In the emphysema group, the mean axial CT diameter was significantly smaller than the mean pathological diameter (p = 0.025/0.001 for reader 1/2), whereas in the non-emphysema group, the mean axial CT diameter was not significantly different from the pathological one for both readers. The difference between CT axial diameter and pathological diameter (= CT diameter - pathological diameter) was significantly smaller (i.e., had a stronger tendency toward underestimation on radiological measurements) in the emphysema group compared with the non-emphysema group (p = 0.014/0.008 for reader 1/2), and the difference was significantly smaller in tumors sized > 30 mm than tumors sized ≤ 20 mm in both groups.

Conclusions: Tumor size is significantly smaller on preoperative CT in patients with severe emphysema compared to patients without emphysema, especially in the case of large tumors. MPR measurement using the widest of three dimensions should be used to select T-stage for patients with severe emphysema.

Key Points: • The presence of emphysema affects the accuracy of tumor size measurements on CT. • Compared to patients without emphysema, the tumor size in severe emphysema patients tends to be measured smaller in preoperative CT than the pathological specimen. • This trend is more evident when large tumors are measured on axial CT images alone.
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http://dx.doi.org/10.1007/s00330-021-08105-3DOI Listing
June 2021

Performance changes due to differences in training data for cerebral aneurysm detection in head MR angiography images.

Jpn J Radiol 2021 Jun 14. Epub 2021 Jun 14.

Department of Radiology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Purpose: The performance of computer-aided detection (CAD) software depends on the quality and quantity of the dataset used for machine learning. If the data characteristics in development and practical use are different, the performance of CAD software degrades. In this study, we investigated changes in detection performance due to differences in training data for cerebral aneurysm detection software in head magnetic resonance angiography images.

Materials And Methods: We utilized three types of CAD software for cerebral aneurysm detection in MRA images, which were based on 3D local intensity structure analysis, graph-based features, and convolutional neural network. For each type of CAD software, we compared three types of training pattern, which were two types of training using single-site data and one type of training using multisite data. We also carried out internal and external evaluations.

Results: In training using single-site data, the performance of CAD software largely and unpredictably fluctuated when the training dataset was changed. Training using multisite data did not show the lowest performance among the three training patterns for any CAD software and dataset.

Conclusion: The training of cerebral aneurysm detection software using data collected from multiple sites is desirable to ensure the stable performance of the software.
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http://dx.doi.org/10.1007/s11604-021-01153-1DOI Listing
June 2021

Automated detection of brain metastases on non-enhanced CT using single-shot detectors.

Neuroradiology 2021 Jun 10. Epub 2021 Jun 10.

Department of Radiology, The Graduate School of Medicine, University of Tokyo, 7‑3‑1 Hongo, Bunkyo‑ku, Tokyo, 113‑8655, Japan.

Purpose: To develop and investigate deep learning-based detectors for brain metastases detection on non-enhanced (NE) CT.

Methods: The study included 116 NECTs from 116 patients (81 men, age 66.5 ± 10.6 years) to train and test single-shot detector (SSD) models using 89 and 27 cases, respectively. The annotation was performed by three radiologists using bounding-boxes defined on contrast-enhanced CT (CECT) images. NECTs were coregistered and resliced to CECTs. The detection performance was evaluated at the SSD's 50% confidence threshold using sensitivity, positive-predictive value (PPV), and the false-positive rate per scan (FPR). For false negatives and true positives, binary logistic regression was used to examine the possible contributing factors.

Results: For lesions 6 mm or larger, the SSD achieved a sensitivity of 35.4% (95% confidence interval (CI): [32.3%, 33.5%]); 51/144) with an FPR of 14.9 (95% CI [12.4, 13.9]). The overall sensitivity was 23.8% (95% CI: [21.3%, 22.8%]; 55/231) and PPV was 19.1% (95% CI: [18.5%, 20.4%]; 98/ of 513), with an FPR of 15.4 (95% CI [12.9, 14.5]). Ninety-five percent of the lesions that SSD failed to detect were also undetectable to radiologists (168/176). Twenty-four percent of the lesions (13/50) detected by the SSD were undetectable to radiologists. Logistic regression analysis indicated that density, necrosis, and size contributed to the lesions' visibility for radiologists, while for the SSD, the surrounding edema also enhanced the detection performance.

Conclusion: The SSD model we developed could detect brain metastases larger than 6 mm to some extent, a quarter of which were even retrospectively unrecognizable to radiologists.
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http://dx.doi.org/10.1007/s00234-021-02743-6DOI Listing
June 2021

Fat-forming solitary fibrous tumor of the sacrum: A case report and literature review.

Radiol Case Rep 2021 Jul 25;16(7):1874-1877. Epub 2021 May 25.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8655, Japan.

Fat-forming variant of solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm. Here we report the case of a 33-year-old woman who developed pain and muscle weakness from the posterior aspect of the right hip to lower extremity. Imaging examinations revealed a mass with fatty components and hypervascular solid components filling the sacral spinal canal and sacral foramen. The sacral mass was resected and histological examination of the specimens revealed patternless proliferation of short spindle-shaped cells with staghorn blood vessels. A number of mature adipocyte-like cells were also observed. The tumor cells were positive for STAT6 and the nuclei of the adipocytes were also positive, which was diagnostic for fat-forming SFT.
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http://dx.doi.org/10.1016/j.radcr.2021.04.052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8170013PMC
July 2021

Prognostic value of pre-treatment maximum standardized uptake value and CRP in radiotherapy of esophageal cancer.

Mol Clin Oncol 2021 Jul 25;15(1):146. Epub 2021 May 25.

Department of Radiology, University of Tokyo Hospital, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.

The aim of the present study was to evaluate the prognostic value of the pre-treatment maximum standardized uptake value (SUV) and CRP in patients who underwent chemoradiotherapy for esophageal squamous cell carcinoma. A retrospective review of 69 consecutive patients with esophageal cancer who underwent concurrent chemoradiotherapy between 2013 and 2016 was performed. The total radiotherapy doses were 50, 50.4 or 60 Gy. The endpoints of the present study were overall survival (OS) and disease-free survival (DFS). The median follow-up for censored cases was 45.7 months. In 56 patients, F-fluorodeoxyglucose positron emission tomography was performed within 1 month prior to chemoradiotherapy. Data on CRP within 1 month prior to chemoradiotherapy were available for all patients. In the group of SUV >12.85, the rates of 2-year OS and DFS were 49.0 and 35.7%, respectively. In the group of SUV ≤12.85, these values were 72.4 and 67.1%, respectively (P=0.048 and P=0.057, respectively). In the group of CRP ≥1 mg/dl, these percentages were 38.5 and 25.0%, respectively. In the group of CRP <1 mg/dl, these rates were 71.2 and 59.7%, respectively (P=0.013 and P<0.001, respectively). A multivariate analysis revealed that pre-treatment serum CRP levels remained an independent prognostic factor for both OS and DFS [OS: hazard ratio (HR), 0.25, P=001; DFS: HR, 0.28, P=0.005]. In conclusion, high SUV was associated with lower OS, while high CRP was associated with lower OS and DFS.
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http://dx.doi.org/10.3892/mco.2021.2308DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8165700PMC
July 2021

Volumetric differences in gray and white matter of cerebellar Crus I/II across the different clinical stages of schizophrenia.

Psychiatry Clin Neurosci 2021 Jun 3. Epub 2021 Jun 3.

Center for Evolutionary Cognitive Science, Graduate School of Art and Sciences, The University of Tokyo, Tokyo, Japan.

Aim: Schizophrenia is considered to be a disorder of progressive structural brain abnormalities. Previous studies have indicated that the cerebellar Crus I/II plays a critical role in schizophrenia. We aimed to investigate how specific morphological features in the Crus I/II at different critical stages of the schizophrenia spectrum contribute to the disease.

Methods: The study involved 73 participants on the schizophrenia spectrum (28 with ultra-high risk for psychosis [UHR], 17 with first-episode schizophrenia [FES], and 28 with chronic schizophrenia) and 79 healthy controls. We undertook a detailed investigation into differences in Crus I/II volume using a semiautomated segmentation method optimized for the cerebellum. We analyzed the effects of group and sex, as well as their interaction, on Crus I/II volume in gray matter (GM) and white matter (WM).

Results: Significant group × sex interactions were found in WM volumes of the bilateral Crus I/II; the males with UHR demonstrated significantly larger WM volumes compared with the other male groups, whereas no significant group differences were found in the female groups. Additionally, WM and GM volumes of the Crus I/II had positive associations with symptom severity in the UHR group, whereas, in contrast, GM volumes in the FES group were negatively associated with symptom severity.

Conclusions: The present findings provide evidence that the morphology of Crus I/II is involved in schizophrenia in a sex- and disease stage-dependent manner. Additionally, alterations of WM volumes of Crus I/II may have potential as a biological marker of early detection and treatment for individuals with UHR.
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http://dx.doi.org/10.1111/pcn.13277DOI Listing
June 2021

Multichannel three-dimensional fully convolutional residual network-based focal liver lesion detection and classification in Gd-EOB-DTPA-enhanced MRI.

Int J Comput Assist Radiol Surg 2021 Jun 1. Epub 2021 Jun 1.

Department of Radiology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Purpose: Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) has high diagnostic accuracy in the detection of liver lesions. There is a demand for computer-aided detection/diagnosis software for Gd-EOB-DTPA-enhanced MRI. We propose a deep learning-based method using one three-dimensional fully convolutional residual network (3D FC-ResNet) for liver segmentation and another 3D FC-ResNet for simultaneous detection and classification of a focal liver lesion in Gd-EOB-DTPA-enhanced MRI.

Methods: We prepared a five-phase (unenhanced, arterial, portal venous, equilibrium, and hepatobiliary phases) series as the input image sets and labeled focal liver lesion (hepatocellular carcinoma, metastasis, hemangiomas, cysts, and scars) images as the output image sets. We used 100 cases to train our model, 42 cases to determine the hyperparameters of our model, and 42 cases to evaluate our model. We evaluated our model by free-response receiver operating characteristic curve analysis and using a confusion matrix.

Results: Our model simultaneously detected and classified focal liver lesions. In the test cases, the detection accuracy for whole focal liver lesions had a true-positive ratio of 0.6 at an average of 25 false positives per case. The classification accuracy was 0.790.

Conclusion: We proposed the simultaneous detection and classification of a focal liver lesion in Gd-EOB-DTPA-enhanced MRI using multichannel 3D FC-ResNet. Our results indicated simultaneous detection and classification are possible using a single network. It is necessary to further improve detection sensitivity to help radiologists.
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http://dx.doi.org/10.1007/s11548-021-02416-yDOI Listing
June 2021

Detectability of pancreatic lesions by low-dose unenhanced computed tomography using iterative reconstruction.

Eur J Radiol 2021 Aug 15;141:109776. Epub 2021 May 15.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.

Objectives: To investigate the detectability of pancreatic cystic lesions and main pancreatic duct dilation by low-dose unenhanced computed tomography (CT).

Material And Methods: This study included 2684 patients who underwent low-dose unenhanced CT using iterative reconstruction and magnetic resonance imaging (MRI) as a part of a health-screening program between February 1, 2019 and December 31, 2019. Patients diagnosed with pancreatic cystic lesions and/or dilatations of the main pancreatic duct on MRI were identified. Detection rates by low dose CT in terms of lesion size were tested for significance by Fisher's exact test.

Results: Of the 2684 patients, 558 (20.8 %) had pancreatic cystic lesions and 22 (0.8 %) had main pancreatic duct dilatation on MRI. The low-dose CT detection rates among the pancreatic cystic lesions were as follows: 1-9-mm cysts, three (0.65 %) of 461; 10-19-mm cysts, 17 (21.25 %) of 80, and ≥20-mm cysts, eight (47.06 %) of 17. The detection rates were significantly higher in the 10-19-mm and the ≥20-mm cyst group than in the 1-9-mm cyst group (p <  0.001). The detection rates among the main pancreatic duct dilatations were as follows: 3-5-mm dilatations, two (11.76 %) of 17 and ≥6-mm dilatations, four (80 %) of five, which were significantly higher rates than that for the 3-5-mm dilatations (p =  0.009).

Conclusion: Small pancreatic cysts and slight main pancreatic duct dilatation were practically undetectable by low-dose unenhanced CT. The application of a low-dose CT protocol as a screening tool in the detection of pancreatic abnormalities is not recommended.
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http://dx.doi.org/10.1016/j.ejrad.2021.109776DOI Listing
August 2021

Rib fracture detection in computed tomography images using deep convolutional neural networks.

Medicine (Baltimore) 2021 May;100(20):e26024

Department of Radiology, Graduate School of Medicine, University of Tokyo, Bunkyo-ku.

Abstract: To evaluate the rib fracture detection performance in computed tomography (CT) images using a software based on a deep convolutional neural network (DCNN) and compare it with the rib fracture diagnostic performance of doctors.We included CT images from 39 patients with thoracic injuries who underwent CT scans. In these images, 256 rib fractures were detected by two radiologists. This result was defined as the gold standard. The performances of rib fracture detection by the software and two interns were compared via the McNemar test and the jackknife alternative free-response receiver operating characteristic (JAFROC) analysis.The sensitivity of the DCNN software was significantly higher than those of both Intern A (0.645 vs 0.313; P < .001) and Intern B (0.645 vs 0.258; P < .001). Based on the JAFROC analysis, the differences in the figure-of-merits between the results obtained via the DCNN software and those by Interns A and B were 0.057 (95% confidence interval: -0.081, 0.195) and 0.071 (-0.082, 0.224), respectively. As the non-inferiority margin was set to -0.10, the DCNN software is non-inferior to the rib fracture detection performed by both interns.In the detection of rib fractures, detection by the DCNN software could be an alternative to the interpretation performed by doctors who do not have intensive training experience in image interpretation.
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http://dx.doi.org/10.1097/MD.0000000000026024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8137061PMC
May 2021

Localization of the central sulcus using the distinctive high signal intensity of the paracentral lobule on T1-weighted images.

Neuroradiology 2021 May 6. Epub 2021 May 6.

Department of Radiology, The University of Tokyo, 1-2-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.

Purpose: The central sulcus is an important landmark in the brain. This study aimed to investigate the distinctive signal of the paracentral lobule (PL) on T1-weighted images (T1WIs; the white PL sign) and evaluate its usefulness as a new method of identifying the central sulcus.

Methods: T1WIs of the brain of 96 participants (age, 58.9 ± 17.9 years; range, 8-87 years) scanned at 3-T MR system were retrospectively reviewed. First, we qualitatively analyzed the signal of the cortex of the PL by comparing it with that of the ipsilateral superior frontal gyrus on a 4-point grading score. Second, we compared the cortical signal intensity and gray/white-matter contrast between the PL and superior frontal gyrus. Third, we evaluated the usefulness of the PL signal for identifying the central sulcus.

Results: The PL cortex was either mildly hyperintense (grade 2) or definitely hyperintense (grade 3) in comparison with that of superior frontal cortex in all participants. The signal intensity of the PL cortex was significantly higher than that of the superior frontal cortex (p < 0.001), whereas the gray/white-matter contrast of the PL was weaker than that of the superior frontal gyrus (p < 0.001). The central sulci were identified with 94.3% accuracy (181/192) using the new method.

Conclusion: The white PL sign may be helpful in identifying the central sulcus, and this approach can be recognized as a new method for identification of the central sulcus.
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http://dx.doi.org/10.1007/s00234-021-02729-4DOI Listing
May 2021

Enhanced structural connectivity within the motor loop in professional boxers prior to a match.

Sci Rep 2021 Apr 27;11(1):9015. Epub 2021 Apr 27.

Department of Radiology, Graduate School of Medicine, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan.

Professional boxers train to reduce their body mass before a match to refine their body movements. To test the hypothesis that the well-defined movements of boxers are represented within the motor loop (cortico-striatal circuit), we first elucidated the brain structure and functional connectivity specific to boxers and then investigated plasticity in relation to boxing matches. We recruited 21 male boxers 1 month before a match (Time1) and compared them to 22 age-, sex-, and body mass index (BMI)-matched controls. Boxers were longitudinally followed up within 1 week prior to the match (Time2) and 1 month after the match (Time3). The BMIs of boxers significantly decreased at Time2 compared with those at Time1 and Time3. Compared to controls, boxers presented significantly higher gray matter volume in the left putamen, a critical region representing motor skill training. Boxers presented significantly higher functional connectivity than controls between the left primary motor cortex (M1) and left putamen, which is an essential region for establishing well-defined movements. Boxers also showed significantly higher structural connectivity in the same region within the motor loop from Time1 to Time2 than during other periods, which may represent the refined movements of their body induced by training for the match.
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http://dx.doi.org/10.1038/s41598-021-88368-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8079439PMC
April 2021

Patient with penile metastasis from prostate cancer and survival over 5 years: A case report with longitudinal evaluation using computed tomography and magnetic resonance imaging.

Radiol Case Rep 2021 Jun 26;16(6):1255-1258. Epub 2021 Mar 26.

Department of Radiology, Tokyo Metropolitan Bokutoh Hospital, Tokyo, Japan.

Penile metastasis of malignant tumors is a very rare condition, often occurring as a part of systemic metastases, and is therefore associated with a poor prognosis. Although there have been reports of magnetic resonance imaging findings of penile metastasis, longitudinal imaging changes have not been presented previously. We report a case of a 80-year-old male patient with penile metastasis from prostate adenocarcinoma. First magnetic resonance imaging demonstrated multiple penile nodules in the left corpus cavernosum corpora cavernosa, and these nodules were fused and across the septum of the penis, forming an enlarged, diffusely spreading mass on the follow-up exam 5 years later. In this case, a longitudinal evaluation of magnetic resonance imaging demonstrated the course of the extension of the rare penile metastasis.
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http://dx.doi.org/10.1016/j.radcr.2021.02.064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8041660PMC
June 2021

Diagnostic prediction of COVID-19 based on clinical and radiological findings in a relatively low COVID-19 prevalence area.

Respir Investig 2021 Jul 29;59(4):446-453. Epub 2021 Mar 29.

Department of Respiratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

Background: Distinguishing coronavirus disease 2019 (COVID-19) pneumonia from other lung diseases is often difficult, especially in a highly comorbid patient population in a low prevalence region. We aimed to distinguish clinical data and computed tomography (CT) images between COVID-19 and other lung diseases in an advanced care hospital.

Methods: We assessed clinical characteristics, laboratory data, and chest CT images of patients with COVID-19 and non-COVID-19 patients who were suspected of having COVID-19 between February 20 and May 21, 2020, at the University of Tokyo Hospital.

Results: Typical appearance for COVID-19 on CT images were found in 24 of 29 COVID-19 cases and 21 of 168 non-COVID-19 cases, according to the Radiological Society of North America Expert Consensus Statement (for predicting COVID-19, sensitivity 0.828, specificity 0.875, positive predictive value 0.533, negative predictive value 0.967). When we focused on cases with typical CT images, loss of taste or smell, and close contact with COVID-19 patients were exclusive characteristics for the COVID-19 cases. Among laboratory data, high fibrinogen (P < 0.01) and low white blood cell count (P < 0.01) were good predictors for COVID-19 with typical CT images in multivariate analysis.

Conclusions: In a relatively low prevalence region, CT screening has high sensitivity to COVID-19 in patients with suspected symptoms. When chest CT findings are typical for COVID-19, close contact, loss of taste or smell, lower white blood cell count, and higher fibrinogen are good predictors for COVID-19.
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http://dx.doi.org/10.1016/j.resinv.2021.03.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8006199PMC
July 2021

Comparison of Chest CT Grading Systems in Coronavirus Disease 2019 (COVID-19) Pneumonia.

Radiol Cardiothorac Imaging 2020 Dec 5;2(6):e200492. Epub 2020 Nov 5.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan (S.I., R.K., Y.N., Y.W., W.G., O.A,); Department of Radiology, Japan Self-Defense Forces Central Hospital, 1-2-24, Ikejiri, Setagaya-ku, Tokyo, 154-0001, Japan (S.I., A.F.); Department of Radiology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22, Honkomagome, Bunkyo-ku, Tokyo, 113-8677, Japan (M.K.); Department of Radiology, National Center for Geriatrics and Gerontology, 7-430, Morioka-cho, Obu, Aichi, 474-8511, Japan (K.S.); Department of Radiology, National Defense Medical College, 3-2, Namiki, Tokorozawa-shi, Saitama, 359-8513, Japan (H.S.); Clinical Research Promotion Center, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan (T.K.); Department of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Chongno-gu, Seoul 03080, Republic of Korea (S.H.Y.); Department of Respiratory Medicine, Japan Self-Defense Forces Central Hospital, 1-2-24, Ikejiri, Setagaya-ku, Tokyo, 154-0001, Japan (Y.U.); Department of Neurology and Neuroscience, Nagoya City University Graduate School of Medical Sciences, 1, Kawasumi, Mizuho-ku, Nagoya, 467-8601, Japan (Y.U.).

Purpose: To compare the performance and interobserver agreement of the COVID-19 Reporting and Data System (CO-RADS), the COVID-19 imaging reporting and data system (COVID-RADS), the RSNA expert consensus statement, and the British Society of Thoracic Imaging (BSTI) guidance statement.

Materials And Methods: In this case-control study, total of 100 symptomatic patients suspected of having COVID-19 were included: 50 patients with COVID-19 (59±17 years, 38 men) and 50 patients without COVID-19 (65±24 years, 30 men). Eight radiologists independently scored chest CT images of the cohort according to each reporting system. The area under the receiver operating characteristic curves (AUC) and interobserver agreements were calculated and statistically compared across the systems.

Results: A total of 800 observations were made for each system. The level of suspicion of COVID-19 correlated with the RT-PCR positive rate except for the "negative for pneumonia" classifications in all the systems (Spearman's coefficient: ρ=1.0, =<.001 for all the systems). Average AUCs were as follows: CO-RADS, 0.84 (95% confidence interval, 0.83-0.85): COVID-RADS, 0.80 (0.78-0.81): the RSNA statement, 0.81 (0.79-0.82): and the BSTI statement, 0.84 (0.812-0.86). Average Cohen's kappa across observers was 0.62 (95% confidence interval, 0.58-0.66), 0.63 (0.58-0.68), 0.63 (0.57-0.69), and 0.61 (0.58-0.64) for CO-RADS, COVID-RADS, the RSNA statement and the BSTI statement, respectively. CO-RADS and the BSTI statement outperformed COVID-RADS and the RSNA statement in diagnostic performance (=.<.05 for all the comparison).

Conclusions: CO-RADS, COVID-RADS, the RSNA statement and the BSTI statement provided reasonable performances and interobserver agreements in reporting CT findings of COVID-19.
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http://dx.doi.org/10.1148/ryct.2020200492DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7650298PMC
December 2020

Texture Analysis in Brain Tumor MR Imaging.

Magn Reson Med Sci 2021 Mar 10. Epub 2021 Mar 10.

Department of Radiology, Graduate School of Medicine, The University of Tokyo.

Texture analysis, as well as its broader category radiomics, describes a variety of techniques for image analysis that quantify the variation in surface intensity or patterns, including some that are imperceptible to the human visual system. Cerebral gliomas have been most rigorously studied in brain tumors using MR-based texture analysis (MRTA) to determine the correlation of various clinical measures with MRTA features. Promising results in cerebral gliomas have been shown in the previous MRTA studies in terms of the correlation with the World Health Organization grades, risk stratification in gliomas, and the differentiation of gliomas from other brain tumors. Multiple MRTA studies in gliomas have repeatedly shown high performance of entropy, a measure of the randomness in image intensity values, of either histogram- or gray-level co-occurrence matrix parameters. Similarly, researchers have applied MRTA to other brain tumors, including meningiomas and pediatric posterior fossa tumors.However, the value of MRTA in the clinical use remains undetermined, probably because previous studies have shown only limited reproducibility of the result in the real world. The low-to-modest generalizability may be attributed to variations in MRTA methods, sampling bias that originates from single-institution studies, and overfitting problems to a limited number of samples.To enhance the reliability and reproducibility of MRTA studies, researchers have realized the importance of standardizing methods in the field of radiomics. Another advancement is the recent development of a comprehensive assessment system to ensure the quality of a radiomics study. These two-way approaches will secure the validity of upcoming MRTA studies. The clinical use of texture analysis in brain MRI will be accelerated by these continuous efforts.
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http://dx.doi.org/10.2463/mrms.rev.2020-0159DOI Listing
March 2021

CT imaging findings of lenvatinib-induced enteritis.

Abdom Radiol (NY) 2021 07 5;46(7):3066-3074. Epub 2021 Mar 5.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Objectives: To evaluate the relationship between abnormal findings on abdomino-pelvic CT and adverse events in oncologic patients treated with lenvatinib, and their relationship with treatment planning.

Methods: This single institutional retrospective study included 58 patients with unresectable hepatocellular carcinoma or unresectable thyroid carcinoma (mean age ± standard deviation 69.6 ± 10.0 years; range 39-84 years; 48 men) who underwent CT between October 2016 and July 2020. Two radiologists who were blinded to clinical information including the presence or absence of diarrhea evaluated the imaging findings, including the presence/absence of enteritis in each intestinal segment. Gastrointestinal adverse events (diarrhea, decreased appetite, nausea, and vomiting) and other drug-induced adverse events requiring treatment or follow-up during lenvatinib treatment were also investigated. The frequency of these adverse events was compared between the patients with and without enteritis using Fisher's exact test or the Mann-Whitney U test.

Results: Enteritis was found on CT in the majority (33/58 [56.9%]) of the patients, and most of them (25/33 [75.8%]) showed duodenojejunitis. The frequency of gastrointestinal adverse events (28/33 [84.8%] vs. 13/25 [56.0%], p = 0.009), diarrhea (20/33 [60.6%] vs. 3/25 [12.0%], p < 0.001), and drug interruptions (25/33 [75.8%] vs. 10/25 [40.0%], p = 0.008) and the number of other adverse events (3.9 ± 1.7 vs. 2.3 ± 1.3, p < 0.001) were significantly higher in the patients with enteritis on CT than in those without.

Conclusions: Lenvatinib-induced enteritis frequently involved the duodenum and jejunum and was related to a significantly higher frequency of treatment interruptions and gastrointestinal adverse events.
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http://dx.doi.org/10.1007/s00261-021-03006-xDOI Listing
July 2021

Computer-aided detection of cerebral aneurysms with magnetic resonance angiography: usefulness of volume rendering to display lesion candidates.

Jpn J Radiol 2021 Jul 27;39(7):652-658. Epub 2021 Feb 27.

Division of Radiology and Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Purpose: The clinical usefulness of computer-aided detection of cerebral aneurysms has been investigated using different methods to present lesion candidates, but suboptimal methods may have limited its usefulness. We compared three presentation methods to determine which can benefit radiologists the most by enabling them to detect more aneurysms.

Materials And Methods: We conducted a multireader multicase observer performance study involving six radiologists and using 470 lesion candidates output by a computer-aided detection program, and compared the following three different presentation methods using the receiver operating characteristic analysis: (1) a lesion candidate is encircled on axial slices, (2) a lesion candidate is overlaid on a volume-rendered image, and (3) combination of (1) and (2). The response time was also compared.

Results: As compared with axial slices, radiologists showed significantly better detection performance when presented with volume-rendered images. There was no significant difference in response time between the two methods. The combined method was associated with a significantly longer response time, but had no added merit in terms of diagnostic accuracy.

Conclusion: Even with the aid of computer-aided detection, radiologists overlook many aneurysms if the presentation method is not optimal. Overlaying colored lesion candidates on volume-rendered images can help them detect more aneurysms.
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http://dx.doi.org/10.1007/s11604-021-01099-4DOI Listing
July 2021

CT imaging findings of anti-PD-1 inhibitor-related enterocolitis.

Abdom Radiol (NY) 2021 07 26;46(7):3033-3043. Epub 2021 Feb 26.

Department of Radiology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo, 113-8677, Japan.

Purpose: Immune checkpoint inhibitors promote the antitumor activity of T cells; however, there is a risk of side effects. The aim of this study was to characterize the computed tomography (CT) findings of one such side effect, anti-programmed cell death-1 antibody-related enterocolitis (αPD-1-EC).

Methods: This single-institution retrospective study included 21 patients with αPD-1-EC who underwent CT between January 2015 and April 2020. Two board-certified radiologists independently evaluated the CT findings, including the pattern of intestinal wall enhancement, maximum bowel wall thickness, maximum appendiceal diameter, and involvement of enterocolitis in each intestinal segment. Symptoms and their severity were also investigated.

Results: Pancolitis and skip lesions involving both the rectosigmoid colon and the cecum were found in 9 patients each (42.9%). The rectum was the most frequently involved lesion (18/21, 85.7%), and appendiceal involvement was found in 11 patients (52.4%). The most frequent wall enhancement pattern was the gray pattern (i.e., mild homogeneous enhancement of the thickened bowel wall). The mean maximum diameter of the involved appendix was 9.6 ± 4.5 mm (range 4.5-18 mm). Frequent symptoms included diarrhea (21/21), fever (8/21), and abdominal pain (7/21). Other concomitant immune-related adverse events were found in 6 patients.

Conclusions: Pancolitis, skip lesions, and appendiceal involvement were frequent in patients with αPD-1-EC. When combining these characteristic findings with other clinical findings, such as low-grade diarrhea, other concomitant immune-related adverse events, and anti-PD-1 therapy administration, CT may be a useful diagnostic tool for αPD-1-EC.
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http://dx.doi.org/10.1007/s00261-021-02986-0DOI Listing
July 2021

Longitudinal comparison of ascites attenuation between antemortem and postmortem computed tomography.

Forensic Sci Int 2021 Apr 18;321:110727. Epub 2021 Feb 18.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.

Objective: To investigate the changes in ascites attenuation between antemortem (AMCT) and postmortem computed tomography (PMCT) analyses of the same subjects.

Methods: Thirty-five subjects who underwent unenhanced or enhanced AMCT within 7 days before death, unenhanced PMCT, and autopsy were evaluated. In each subject, ascites attenuation was measured at similar sites on AMCT and PMCT. Attenuation changes were evaluated in 42 unenhanced AMCT/PMCT site pairs (23 subjects) and 20 enhanced AMCT/PMCT site pairs (12 subjects). Factors contributing to CT attenuation changes were also assessed, including the time interval between AMCT and PMCT, serum albumin level, estimated glomerular filtration rate, and ascites volume.

Results: Significantly elevated CT attenuation was observed between enhanced AMCT and PMCT (12.2 ± 6.3 vs. 18.7 ± 10.4 Hounsfield units; paired t-test, p = 0.006), but not between unenhanced AMCT and PMCT (13.5 ± 8.9 vs. 13.4 ± 9.3; p = 0.554). A significant inverse association was observed between the degree of CT attenuation change and the time interval between enhanced AMCT and PMCT (Spearman's rank correlation coefficient, r = -0.56, p = 0.01).

Conclusions: We confirmed an elevated level of ascites attenuation on PMCT relative to AMCT in subjects who underwent enhanced AMCT shortly before death.
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http://dx.doi.org/10.1016/j.forsciint.2021.110727DOI Listing
April 2021

Reliability of Changes in Brain Volume Determined by Longitudinal Voxel-Based Morphometry.

J Magn Reson Imaging 2021 08 24;54(2):609-616. Epub 2021 Feb 24.

Department of Radiology, Graduate School of Medicine, University of Tokyo, Tokyo, 113-8655, Japan.

Background: Longitudinal magnetic resonance imaging (MRI) studies have become increasingly important to assess the changes in brain morphology during normal aging and neurodegenerative disorders. However, the reliability of longitudinal morphometric changes has not been fully evaluated.

Purpose: To examine the reliability of longitudinal (2-year) changes in brain morphology determined by longitudinal voxel-based morphometry (VBM) in healthy elderly subjects, patients with mild cognitive impairment (MCI), and patients with Alzheimer's disease (AD).

Study Type: Retrospective analysis.

Subjects: Twenty-four healthy elderly subjects, 28 MCI patients, and 16 AD patients.

Field Strength/sequence: A 1.5 T, magnetization-prepared rapid gradient-echo.

Assessment: Longitudinal (2-year) changes in gray matter volume determined by longitudinal VBM processing, and visual assessment of image quality.

Statistical Tests: Intraclass correlation coefficient (ICC) and Kruskal-Wallis test.

Results: The ICC maps differed among the three groups. The mean ICC was 0.81 overall (0.86 for healthy elderly subjects, 0.75 for MCI patients, and 0.76 for AD patients). The reliability was good to excellent (ICC, 0.60-1.00) for 92% of voxels (99% for healthy elderly subjects, 83% for MCI patients, and 83% for AD patients). The image quality differed significantly among the three groups (P < 0.05).

Data Conclusion: These results indicate that the reliability of longitudinal gray matter volume changes by VBM is good to excellent for most voxels. However, reliability may be affected by the disease, possibly due to differences in head motion during imaging. Evidence Level 3 Technical Efficacy Stage 1.
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http://dx.doi.org/10.1002/jmri.27568DOI Listing
August 2021

A retrospective analysis of radiotherapy in the treatment of external auditory canal carcinoma.

Mol Clin Oncol 2021 Mar 13;14(3):45. Epub 2021 Jan 13.

Department of Radiology, The University of Tokyo Hospital, Bunkyo-ku, Tokyo 113-8655, Japan.

External auditory canal carcinoma (EACC) is a rare disease. The current study aimed to evaluate the clinical outcomes of patients treated with external beam radiotherapy (EBRT) for EACC. The present study retrospectively reviewed 34 consecutive patients treated for EACC with EBRT between February 2001 and January 2019 at the University of Tokyo Hospital. Clinical staging was performed according to the modified Pittsburgh classification. Of all the included patients, seven patients were in the early stages (I or II) and 27 in the advanced stages (III or IV) of EACC. A total of 16 patients underwent EBRT and surgery (S+RT) pre- and/or postoperatively, while 18 patients underwent definitive radiotherapy (dRT). The median prescribed doses for the S+RT and dRT groups were 66 and 70 Gy, respectively. The median follow-up period for all patients was 22.4 months (range, 2-205 months). The 5-year overall survival rates of the S+RT and dRT groups were 66.7 and 45.1%, respectively. The progression-free survival rate at 5-year was 55.6% (95% confidence interval: 36.5-71.1%) for the entire cohort. A total of 14 patients experienced disease relapse after treatment, consisting of 11 locoregional recurrences and three distant metastases. The current study revealed the clinical outcomes of EBRT for EACC.
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http://dx.doi.org/10.3892/mco.2021.2207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7818098PMC
March 2021

Unsupervised Deep Anomaly Detection in Chest Radiographs.

J Digit Imaging 2021 Apr 8;34(2):418-427. Epub 2021 Feb 8.

Department of Radiology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.

The purposes of this study are to propose an unsupervised anomaly detection method based on a deep neural network (DNN) model, which requires only normal images for training, and to evaluate its performance with a large chest radiograph dataset. We used the auto-encoding generative adversarial network (α-GAN) framework, which is a combination of a GAN and a variational autoencoder, as a DNN model. A total of 29,684 frontal chest radiographs from the Radiological Society of North America Pneumonia Detection Challenge dataset were used for this study (16,880 male and 12,804 female patients; average age, 47.0 years). All these images were labeled as "Normal," "No Opacity/Not Normal," or "Opacity" by board-certified radiologists. About 70% (6,853/9,790) of the Normal images were randomly sampled as the training dataset, and the rest were randomly split into the validation and test datasets in a ratio of 1:2 (7,610 and 15,221). Our anomaly detection system could correctly visualize various lesions including a lung mass, cardiomegaly, pleural effusion, bilateral hilar lymphadenopathy, and even dextrocardia. Our system detected the abnormal images with an area under the receiver operating characteristic curve (AUROC) of 0.752. The AUROCs for the abnormal labels Opacity and No Opacity/Not Normal were 0.838 and 0.704, respectively. Our DNN-based unsupervised anomaly detection method could successfully detect various diseases or anomalies in chest radiographs by training with only the normal images.
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http://dx.doi.org/10.1007/s10278-020-00413-2DOI Listing
April 2021

Automatic detection of brain metastases on contrast-enhanced CT with deep-learning feature-fused single-shot detectors.

Eur J Radiol 2021 Mar 30;136:109577. Epub 2021 Jan 30.

Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Purpose: Despite the potential usefulness, no automatic detector is available for brain metastases on contrast-enhanced CT (CECT). The study aims to develop and investigate deep learning-based detectors for brain metastases detection on CECT.

Method: The study included 127 CECTs from 127 patients (65.5 years±11.1; 87 men). The ground-truth annotation was performed semi-automatically by applying connected-component analysis to the binarized dataset by three radiologists. Single-shot detector (SSD) algorithms, with and without a feature-fusion module, were developed and trained using 97 scans. The performance was evaluated at the detector's 50 % confidence threshold with the remaining 30 scans using sensitivity, positive-predictive value (PPV), and the false-positive rate per scan (FPR).

Results: Feature-fused SSD achieved an overall sensitivity of 88.1 % (95 % confidence interval [CI]: [85.2 %,88.6 %]; 214/243) and PPV of 36.0 % (95 % CI: [33.7 %,37.1 %]; 233/648), with 13.8 FPR (95 % CI: [12.7,15.0]). Lesions < 3 mm had a sensitivity of 23.1 % (95 % CI: [21.2 %,40.0 %]; 3/13), with 0.2 FPR (95 % CI: [0.23,0.65]). Lesions measuring 3-6 mm had a sensitivity of 80.0 % (95 % CI: [76.0 %,79.8 %]); 60/75) with 5.8 FPR (95 % CI: [5.0,6.2]). Lesions > 6 mm had a sensitivity of 97.4 % (95 % CI: [94.1 %,97.4 %]); 151/155) with 7.9 FPR (95 % CI: [7.2,8.5]). Feature-fused SSD had a significantly higher overall sensitivity (p = 0.03, t = 2.75) or sensitivity for lesions < 3 mm (p = 0.002, t = 4.49) than baseline SSD, while the overall PPV was similar (p = 0.96, t = -0.02).

Conclusions: The SSD algorithm identified brain metastases on CECT with reasonable accuracy for lesions > 3 mm without pre/post-processing.
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http://dx.doi.org/10.1016/j.ejrad.2021.109577DOI Listing
March 2021

Parkinson's disease: deep learning with a parameter-weighted structural connectome matrix for diagnosis and neural circuit disorder investigation.

Neuroradiology 2021 Jan 22. Epub 2021 Jan 22.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Purpose: To investigate whether Parkinson's disease (PD) can be differentiated from healthy controls and to identify neural circuit disorders in PD by applying a deep learning technique to parameter-weighted and number of streamlines (NOS)-based structural connectome matrices calculated from diffusion-weighted MRI.

Methods: In this prospective study, 115 PD patients and 115 healthy controls were enrolled. NOS-based and parameter-weighted connectome matrices were calculated from MRI images obtained with a 3-T MRI unit. With 5-fold cross-validation, diagnostic performance of convolutional neural network (CNN) models using those connectome matrices in differentiating patients with PD from healthy controls was evaluated. To identify the important brain connections for diagnosing PD, gradient-weighted class activation mapping (Grad-CAM) was applied to the trained CNN models.

Results: CNN models based on some parameter-weighted structural matrices (diffusion kurtosis imaging (DKI)-weighted, neurite orientation dispersion and density imaging (NODDI)-weighted, and g-ratio-weighted connectome matrices) showed moderate performance (areas under the receiver operating characteristic curve (AUCs) = 0.895, 0.801, and 0.836, respectively) in discriminating PD patients from healthy controls. The DKI-weighted connectome matrix performed significantly better than the conventional NOS-based matrix (AUC = 0.761) (DeLong's test, p < 0.0001). Alterations of neural connections between the basal ganglia and cerebellum were indicated by applying Grad-CAM to the NODDI- and g-ratio-weighted matrices.

Conclusion: Patients with PD can be differentiated from healthy controls by applying the deep learning technique to the parameter-weighted connectome matrices, and neural circuit disorders including those between the basal ganglia on one side and the cerebellum on the contralateral side were visualized.
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http://dx.doi.org/10.1007/s00234-021-02648-4DOI Listing
January 2021