Faculty Profiles - NAGANAWA, Shinji

Papers - NAGANAWA, Shinji

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An Investigation of Water Diffusivity Changes along the Perivascular Space in Elderly Subjects with Hypertension Reviewed

J. Kikuta, K. Kamagata, K. Takabayashi, T. Taoka, H. Yokota, C. Andica, A. Wada, Y. Someya, Y. Tamura, R. Kawamori, H. Watada, S. Naganawa, S. Aoki

American Journal of Neuroradiology Vol. 43 ( 1 ) page： 48 - 55 2022.1

The Glymphatic System: A Review of the Challenges in Visualizing its Structure and Function with MR Imaging. Reviewed

Shinji Naganawa, Toshiaki Taoka

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 21 ( 1 ) page： 182 - 194 2022

Authorship：Lead author,　Last author Language：English Publishing type：Research paper (scientific journal)

The central nervous system (CNS) was previously thought to be the only organ system lacking lymphatic vessels to remove waste products from the interstitial space. Recently, based on the results from animal experiments, the glymphatic system was hypothesized. In this hypothesis, cerebrospinal fluid (CSF) enters the periarterial spaces, enters the interstitial space of the brain parenchyma via aquaporin-4 (AQP4) channels in the astrocyte end feet, and then exits through the perivenous space, thereby clearing waste products. From the perivenous space, the interstitial fluid drains into the subarachnoid space and meningeal lymphatics of the parasagittal dura. It has been reported that the glymphatic system is particularly active during sleep. Impairment of glymphatic system function might be a cause of various neurodegenerative diseases such as Alzheimer's disease, normal pressure hydrocephalus, glaucoma, and others. Meningeal lymphatics regulate immunity in the CNS. Many researchers have attempted to visualize the function and structure of the glymphatic system and meningeal lymphatics in vivo using MR imaging. In this review, we aim to summarize these in vivo MR imaging studies and discuss the significance, current limitations, and future directions. We also discuss the significance of the perivenous cyst formation along the superior sagittal sinus, which is recently discovered in the downstream of the glymphatic system.

DOI： 10.2463/mrms.rev.2020-0122

Cross-sectional Area of the Superior Petrosal Sinus is Reduced in Patients with Significant Endolymphatic Hydrops. Reviewed

Shinji Naganawa, Rintaro Ito, Hisashi Kawai, Mariko Kawamura, Toshiaki Taoka, Tadao Yoshida, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 21 ( 3 ) page： 459 - 467 2022

Authorship：Lead author,　Last author Language：English Publishing type：Research paper (scientific journal)

PURPOSE: To evaluate the relationship between the size of the venous structures related to the inner ear and the degree of endolymphatic hydrops (EH). METHODS: Thirty-four patients with a suspicion of EH underwent whole brain MR imaging including the inner ear. Images were obtained pre- and post-administration, and at 4 and 24 hours after the intravenous administration of a gadolinium-based contrast agent (IV-GBCA). The cross-sectional areas (CSA) of the internal jugular vein (IJV), superior petrosal sinus (SPS), and inferior petrosal sinus (IPS) were measured on the magnetization prepared rapid acquisition of gradient echo (MPRAGE) images obtained immediately after the IV-GBCA. The grade of EH was determined on the hybrid of reversed image of positive endolymph signal and native image of positive perilymph signal (HYDROPS) images obtained at 4 hours after IV-GBCA as no, mild, and significant EH according to the previously proposed grading system for the cochlea and vestibule, respectively. The ipsilateral CSA was compared between groups with each level of EH grade. P < 0.05 was considered statistically significant. RESULTS: There were no statistically significant differences between EH grades for the CSA of the IJV or that of the IPS in either the cochlea or the vestibule. The CSA of the SPS in the groups with significant EH was significantly smaller than that in the group with no EH, for both the cochlea (P < 0.01) and the vestibule (P < 0.05). In an ROC analysis to predict significant EH, the cut-off CSA value in the SPS was 3.905 mm2 for the cochlea (AUC: 0.8762, 95% confidence interval [CI]: 0.7952‒0.9572) and 3.805 mm2 for the vestibule (AUC: 0.7727, 95% CI: 0.6539‒0.8916). CONCLUSION: In the ears with significant EH in the cochlea or vestibule, the CSA of the ipsilateral SPS was smaller than in the ears without EH.

DOI： 10.2463/mrms.mp.2021-0010

MR Imaging of Endolymphatic Hydrops in Five Minutes. Reviewed

Shinji Naganawa, Rintaro Ito, Hisashi Kawai, Mariko Kawamura, Toshiaki Taoka, Mayuko Sakai, Kazushige Ichikawa, Tadao Yoshida, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 21 ( 3 ) page： 401 - 405 2022

Authorship：Lead author,　Last author Language：English Publishing type：Research paper (scientific journal)

In this study, we present images acquired by a fast-imaging method for the evaluation of endolymphatic hydrops after intravenous administration of a single dose of gadolinium-based contrast agent. We utilized the hybrid of reversed image of MR cisternography and a positive perilymph signal by heavily T2- weighted 3D-fluid attenuated inversion recovery-multiplied by T2 (HYDROPS2-Mi2) method combined with deep learning reconstruction denoising. The scan time for the fast protocol was approximately 5 mins, which is far shorter than previously reported scan times. The fast acquisition provides similar image quality and less motion artifacts compared to the longer method.

DOI： 10.2463/mrms.ici.2021-0022

Effects of Head Motion on the Evaluation of Age-related Brain Network Changes Using Resting State Functional MRI. Reviewed

Sanae Kato, Epifanio Bagarinao, Haruo Isoda, Shuji Koyama, Hirohisa Watanabe, Satoshi Maesawa, Daisuke Mori, Kazuhiro Hara, Masahisa Katsuno, Minoru Hoshiyama, Shinji Naganawa, Norio Ozaki, Gen Sobue

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 4 ) page： 338 - 346 2021.12

Language：English Publishing type：Research paper (scientific journal)

PURPOSE: The estimation of functional connectivity (FC) measures using resting state functional MRI (fMRI) is often affected by head motion during functional imaging scans. Head motion is more common in the elderly than in young participants and could therefore affect the evaluation of age-related changes in brain networks. Thus, this study aimed to investigate the influence of head motion in FC estimation when evaluating age-related changes in brain networks. METHODS: This study involved 132 healthy volunteers divided into 3 groups: elderly participants with high motion (OldHM, mean age (±SD) = 69.6 (±5.31), N = 44), elderly participants with low motion (OldLM, mean age (±SD) = 68.7 (±4.59), N = 43), and young adult participants with low motion (YugLM, mean age (±SD) = 27.6 (±5.26), N = 45). Head motion was quantified using the mean of the framewise displacement of resting state fMRI data. After preprocessing all resting state fMRI datasets, several resting state networks (RSNs) were extracted using independent component analysis (ICA). In addition, several network metrics were also calculated using network analysis. These FC measures were then compared among the 3 groups. RESULTS: In ICA, the number of voxels with significant differences in RSNs was higher in YugLM vs. OldLM comparison than in YugLM vs. OldHM. In network analysis, all network metrics showed significant (P < 0.05) differences in comparisons involving low vs. high motion groups (OldHM vs. OldLM and OldHM vs. YugLM). However, there was no significant (P > 0.05) difference in the comparison involving the low motion groups (OldLM vs. YugLM). CONCLUSION: Our findings showed that head motion during functional imaging could significantly affect the evaluation of age-related brain network changes using resting state fMRI data.

DOI： 10.2463/mrms.mp.2020-0081

Evaluating the Effect of Arterial Pulsation on Cerebrospinal Fluid Motion in the Sylvian Fissure of Patients with Middle Cerebral Artery Occlusion Using Low b-value Diffusion-weighted Imaging Reviewed

Toshiaki Taoka, Hisashi Kawai, Toshiki Nakane, Takashi Abe, Rei Nakamichi, Rintaro Ito, Yutaro Sasaki, Ayumi Nishida, Shinji Naganawa

Magnetic Resonance in Medical Sciences Vol. 20 ( 4 ) page： 371 - 377 2021.12

Incidental findings on computed tomography for preoperative assessment before transcatheter aortic valve implantation in Japanese patients. Reviewed

Akihiro Tobe, Akihito Tanaka, Yoshiyuki Tokuda, Yusuke Miki, Kenji Furusawa, Sho Akita, Taro Fujii, Yoshinori Tsutsumi, Hideki Ishii, Shingo Iwano, Shinji Naganawa, Akihiko Usui, Toyoaki Murohara

Heart and vessels Vol. 36 ( 12 ) page： 1911 - 1922 2021.12

Language：English Publishing type：Research paper (scientific journal)

Extra-cardiovascular incidental findings (IFs) on preoperative computed tomography (CT) are frequently observed in transcatheter aortic valve implantation (TAVI) candidates. However, the backgrounds of TAVI candidates and comorbidities differ based on the race and/or country, and data on IFs in a specific population are not always applicable to another. The aim of this study was to assess the prevalence, type, and clinical impact of IFs in Japanese TAVI candidates. This was a retrospective, single-center, observational study. CT reports of 257 TAVI candidates were reviewed, and IFs were classified as (a) insignificant: findings that did not require further investigation, treatment, or follow-up; (b) intermediate: findings that needed to be followed up or were considered for further investigation but did not affect the planning of TAVI; and (c) significant: findings that required further investigation immediately or affected the planning of TAVI. At least one IF was found in 254 patients (98.8%). Insignificant, intermediate, and significant IFs were found in 253 (98.4%), 153 (59.5%), and 34 (13.2%) patients, respectively. Newly indicated significant IFs were found in 19 patients (7.4%). In 2 patients (0.8%), TAVI was canceled because of significant IFs. In patients who consequently underwent TAVI, the presence of significant IFs was not associated with the duration from CT performance to TAVI [28 (19-40) days vs. 27 (19-43) days, p = 0.74] and all-cause mortality during the median follow-up period of 413 (223-805) days (p = 0.44). Almost all Japanese TAVI candidates had at least one IF, and the prevalence of significant IFs was not negligible. Although the presence of significant IFs was not associated with mid-term mortality, appropriate management of IFs was considered important.

DOI： 10.1007/s00380-021-01875-2

FLUID study: study protocol for an open-label, single-centre pilot study to investigate the efFect of Lemborexant on sleep management in Japanese sUbjects aged 50 years and older with Insomnia Disorder. Reviewed International journal

Ippei Okada, Kunihiro Iwamoto, Seiko Miyata, Akihiro Fujimoto, Masaki Tanaka, Manabu Amano, Nao Matsuyama, Toshiaki Taoka, Shinji Naganawa, Norio Ozaki

BMJ open Vol. 11 ( 11 ) page： e054885 2021.11

Language：English Publishing type：Research paper (scientific journal)

INTRODUCTION: Bidirectional associations have been reported between sleep disturbance and both cognitive impairment, including Alzheimer's disease and amyloid beta-peptide (Aβ) accumulation. These relationships can be explained by the glymphatic system, which acts as a garbage drainage system in the brain. As interstitial fluid dynamics are suggested to increase during sleep, clearance of Aβ can be influenced by sleep disturbance or deprivation. We hypothesised that using lemborexant, an orexin receptor antagonist, to improve sleep quality would also improve the function of the glymphatic system. We plan to examine the effect of lemborexant on sleep quality and the glymphatic system among patients with insomnia disorder. METHODS AND ANALYSIS: This pilot study is designed as an open-label, single-arm, single-centre trial. Thirty patients aged 50 years and over with insomnia will be recruited. The participants will take lemborexant (5 mg) at bedtime for 12 weeks and undergo a home-based sleep study at baseline and weeks 4 and 12, as well as MRI examinations to evaluate the glymphatic system at baseline and week 12. The primary outcome will be changes in objective sleep parameters as evaluated using a sleep monitoring system. The secondary outcomes will be changes in subjective sleep parameters. The relationships between changes in sleep parameters and the glymphatic system will be evaluated using diffusion tensor image analysis along the perivascular space, which is called the ALPS-index. Sleep parameters and the ALPS-index will be analysed using a paired t-test or Pearson's correlation coefficient. ETHICS AND DISSEMINATION: The study protocol was approved by Nagoya University Certified Review Board. The findings from this research will be published in peer-reviewed journals and be presented at local, national and international conferences. TRIAL REGISTRATION NUMBER: jRCTs041210024.

DOI： 10.1136/bmjopen-2021-054885

Development of an x-ray-opaque-marker system for quantitative phantom positioning in patient-specific quality assurance Reviewed

Kentaro Suzuki, Takeshi Kamomae, Hiroshi Oguchi, Fumitaka Kawabata, Kazuma Sugita, Kuniyasu Okudaira, Masaki Mori, Shinji Abe, Masataka Komori, Mariko Kawamura, Kazuhiro Ohtakara, Yoshiyuki Itoh, Shinji Naganawa

Physica Medica Vol. 91 page： 121 - 130 2021.11

A case of intraductal tubulopapillary neoplasm of the pancreas originating from the branch duct: cast in the mold sign. Reviewed Open Access

Ryota Horiguchi, Hiroshi Ogawa, Naoya Nagai, Yasuo Takehara, Shinji Naganawa, Yukihiro Yokoyama, Yoshie Shimoyama

Nagoya journal of medical science Vol. 83 ( 4 ) page： 869 - 875 2021.11

Language：English Publishing type：Research paper (scientific journal)

A 59-year-old man with jaundice and lower common bile duct stenosis was referred to our institution for diagnosis and treatment. Computed tomography and magnetic resonance imaging showed a well-circumscribed smoothly marginated solid mass lesion in the pancreatic head. He underwent pyloric preserving pancreatoduodenectomy. Histopathological specimen revealed that the mass was located in the dilated branch duct of the pancreatic head, and an intraductal tubulopapillary neoplasm originating from the branch pancreatic duct was diagnosed. On magnetic resonance cholangiopancreatography, the mass within the dilated duct branch in the pancreatic head was similar to a "cast in the mold" image, which we retrospectively deemed, might be reflecting the nature of this tumor.

DOI： 10.18999/nagjms.83.4.869

Bridging large-scale cortical networks: Integrative and function-specific hubs in the thalamus. Reviewed International journal

Kazuya Kawabata, Epifanio Bagarinao, Hirohisa Watanabe, Satoshi Maesawa, Daisuke Mori, Kazuhiro Hara, Reiko Ohdake, Michihito Masuda, Aya Ogura, Toshiyasu Kato, Shuji Koyama, Masahisa Katsuno, Toshihiko Wakabayashi, Masafumi Kuzuya, Minoru Hoshiyama, Haruo Isoda, Shinji Naganawa, Norio Ozaki, Gen Sobue

iScience Vol. 24 ( 10 ) page： 103106 - 103106 2021.10

Language：English Publishing type：Research paper (scientific journal)

The thalamus is critical for the brain's integrative hub functions; however, the localization and characterization of the different thalamic hubs remain unclear. Using a voxel-level network measure called functional connectivity overlap ratio (FCOR), we examined the thalamus' association with large-scale resting-state networks (RSNs) to elucidate its connector hub roles. Connections to the core-neurocognitive networks were localized in the anterior and medial parts, such as the anteroventral and mediodorsal nuclei areas. Regions functionally connected to the sensorimotor network were distinctively located around the lateral pulvinar nucleus but to a limited extent. Prominent connector hubs include the anteroventral, ventral lateral, and mediodorsal nuclei with functional connections to multiple RSNs. These findings suggest that the thalamus, with extensive connections to most of the RSNs, is well placed as a critical integrative functional hub and could play an important role for functional integration facilitating brain functions associated with primary processing and higher cognition.

DOI： 10.1016/j.isci.2021.103106

Magnetic resonance cisternography imaging findings related to the leakage of Gadolinium into the subarachnoid space Reviewed

Rei Nakamichi, Toshiaki Taoka, Hisashi Kawai, Tadao Yoshida, Michihiko Sone, Shinji Naganawa

Japanese Journal of Radiology Vol. 39 ( 10 ) page： 927 - 937 2021.10

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

<title>Abstract</title><sec>
<title>Purpose</title>
To identify magnetic resonance cisternography (MRC) imaging findings related to Gadolinium-based contrast agent (GBCA) leakage into the subarachnoid space.

</sec><sec>
<title>Materials and methods</title>
The number of voxels of GBCA leakage (V-leak) on 3D-real inversion recovery images was measured in 56 patients scanned 4 h post-intravenous GBCA injection. Bridging veins (BVs) were identified on MRC. The numbers of BVs with surrounding cystic structures (BV-cyst), with arachnoid granulations protruding into the superior sagittal sinus (BV-AG-SSS) and the skull (BV-AG-skull), and including any of these factors (BV-incl) were recorded. Correlations between these variables and V-leak were examined based on the Spearman’s rank correlation coefficient. Receiver-operating characteristic (ROC) curves were generated to investigate the predictive performance of GBCA leakage.

</sec><sec>
<title>Results</title>
V-leak and the number of BV-incl were strongly correlated (<italic>r</italic> = 0.609, <italic>p</italic> < 0.0001). The numbers of BV-cyst and BV-AG-skull had weaker correlations with V-leak (<italic>r</italic> = 0.364, <italic>p</italic> = 0.006; <italic>r</italic> = 0.311, <italic>p</italic> = 0.020, respectively). The number of BV-AG-SSS was not correlated with V-leak. The ROC curve for contrast leakage exceeding 1000 voxels and the number of BV-incl had moderate accuracy, with an area under the curve of 0.871.

</sec><sec>
<title>Conclusion</title>
The number of BV-incl may be a predictor of GBCA leakage and a biomarker for waste drainage function without using GBCA.

</sec>

DOI： 10.1007/s11604-021-01137-1

Other Link： https://link.springer.com/article/10.1007/s11604-021-01137-1/fulltext.html

Imaging diagnosis of autoimmune pancreatitis: computed tomography and magnetic resonance imaging. Reviewed

Hiroshi Ogawa, Yasuo Takehara, Shinji Naganawa

Journal of medical ultrasonics (2001) Vol. 48 ( 4 ) page： 565 - 571 2021.10

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

Autoimmune pancreatitis (AIP) is a pancreatic phenotype of IgG4-related systemic disease. Since its first description in the literature, characteristic imaging features have gradually become known to many clinicians encompassing various specialties in the past quarter century. CT and MRI have been the workhorses for imaging diagnosis of AIP. Typical features include sausage-like swelling of the focal or entire pancreas, duct-penetrating sign, a capsule-like rim of the affected lesions, and homogeneous delayed enhancement or enhanced duct sign after contrast administration, as well as characteristic combined findings reflecting coexisting pathologies in the other organs as a systemic disease. In this review, recent and future developments in CT and MRI that may help diagnose AIP are discussed, including restricted diffusion and perfusion and increased elasticity measured using MR.

DOI： 10.1007/s10396-021-01145-8

The importance of choosing the right strategy to treat small cell carcinoma of the cervix: a comparative analysis of treatments. Reviewed International journal

Mariko Kawamura, Yutaro Koide, Taro Murai, Shunichi Ishihara, Yuuki Takase, Takayuki Murao, Dai Okazaki, Takahiro Yamaguchi, Kaoru Uchiyama, Yoshiyuki Itoh, Takeshi Kodaira, Yuta Shibamoto, Mika Mizuno, Fumitaka Kikkawa, Shinji Naganawa

BMC cancer Vol. 21 ( 1 ) page： 1046 - 1046 2021.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Standard treatments for small cell carcinoma of the cervix (SCCC) have not been established. In this study, we aimed to estimate the optimal treatment strategy for SCCC. METHODS: This was a multicenter retrospective study. Medical records of patients with pathologically proven SCCC treated between 2003 and 2016 were retrospectively analyzed. Overall survival (OS) was plotted using the Kaplan-Meier method. Log-rank tests and Cox regression analysis were used to assess the differences in survival according to stage, treatment strategy, and chemotherapy regimen. RESULTS: Data of 78 patients were collected, and after excluding patients without immunohistopathological staining, 65 patients were evaluated. The median age of the included patients was 47 (range: 24-83) years. The numbers of patients with International Federation of Gynecology and Obstetrics (FIGO) 2018 stages I-IIA, IIB-IVA, IVB were 23 (35%), 34 (52%), and 8 (12%), respectively. Of 53 patients who had undergone chemotherapy, 35 and 18 received SCCC and non-SCCC regimens as their first-line chemotherapy regimen, respectively. The 5-year OS for all patients was 49%, while for patients with FIGO stages I-IIA, IIB-IVA, IVB, it was 60, 50, and 0%, respectively. The 5-year OS rates for patients who underwent treatment with SCCC versus non-SCCC regimens were 59 and 13% (p < 0.01), respectively. This trend was pronounced in locally advanced stages. Multivariate analysis showed that FIGO IVB at initial diagnosis was a significant prognostic factor in all patients. Among the 53 patients who received chemotherapy, the SCCC regimen was associated with significantly better 5-year OS in both the uni- and multivariate analyses. CONCLUSION: Our results suggest that the application of an SCCC regimen such as EP or IP as first-line chemotherapy for patients with locally advanced SCCC may play a key role in OS. These findings need to be validated in future nationwide, prospective clinical studies.

DOI： 10.1186/s12885-021-08772-x

Changes in Vessel Wall Enhancement Related to the Recent Neurological Symptoms in Patients with Moyamoya Disease. Reviewed

Shinsuke Muraoka, Toshiaki Taoka, Hisashi Kawai, Sho Okamoto, Kenji Uda, Shinji Naganawa, Yoshio Araki

Neurologia medico-chirurgica Vol. 61 ( 9 ) page： 515 - 520 2021.9

Language：English Publishing type：Research paper (scientific journal)

Moyamoya disease (MMD) causes intracranial arterial stenosis progression. The progression of intracranial arterial stenosis will increase the risk of ischemic cerebrovascular events. This study aims to investigate the relationship between intracranial arterial stenosis progression, vessel wall enhancement (VWE), and the recent neurological symptoms. A total of 39 MMD patients (12 male; 37.6 ± 18.0 years old) were registered in this study analysis between April 2016 and July 2018. All patients received MRI at registration and 6, 12, and 24 months post-registration. The incidence of ischemic cerebrovascular events (transit ischemic attacks or cerebral infarction) was checked until December 2018. We evaluated the relationship between the intensity of VWE, intracranial arterial stenosis, and the recent neurological symptoms. During the mean follow-up period of 13.8 ± 5.5 months, the changes in VWE were observed in 33 hemispheres (42.3%), stenosis progression was observed in 21 hemispheres (26.9%), and recent neurological symptoms occurred in 10 hemispheres (12.8%). Stenosis progression was observed in 11 hemispheres (33.3%) in the VWE(+) group and ten hemispheres (22.2%) in the VWE(-) group (p = 0.310). The recent neurological symptoms were observed in eight hemispheres (21.2%) in the VWE(+) group and two hemispheres (4.44%) in the VWE(-) group (odds ratio 6.88, 95% confidence interval 1.35-34.98, p = 0.015). The intensity of VWE sometimes changes. The changes in VWE were significantly associated with the recent neurological symptoms but not with stenosis progression.

DOI： 10.2176/nmc.oa.2021-0058

Evaluation of the blood-perilymph barrier in ears with endolymphatic hydrops. Reviewed International journal

Tadao Yoshida, Masumi Kobayashi, Satofumi Sugimoto, Masaaki Teranishi, Shinji Naganawa, Michihiko Sone

Acta oto-laryngologica Vol. 141 ( 8 ) page： 736 - 741 2021.8

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Otological diseases including Meniere's disease (MD) involve endolymphatic hydrops (EH), which can be visualized by magnetic resonance imaging (MRI) with gadolinium contrast agents, but the temporal changes of contrast in the inner ear have not been evaluated. OBJECTIVES: We investigated the permeability of the blood-perilymph barrier (BPB) in ears with EH to evaluate the severity of the inner ear disturbances. MATERIALS AND METHODS: The study included 32 ears from 16 patients with EH or related diseases who underwent MRI. The permeability of the BPB was assessed by the signal-intensity ratio (SIR) at four-time points: before and at 10 min, 4 h, and 24 h after administration of gadolinium for assessing EH. RESULTS: Cochlear EH was found in 25 of the 32 ears, and vestibular EH in 11. The rate of EH was significantly higher in symptomatic ears; however, the existence of EH was not related to SIR values. Nevertheless, SIR values in the basal turn were significantly higher 4 and 24 h after injection of gadolinium in patients aged ≥50 years. CONCLUSION AND SIGNIFICANCE: Higher SIR values observed in older patients with EH indicate severe disturbances of the BPB in the cochlea, which may account for intractable inner ear disturbances in older patients.

DOI： 10.1080/00016489.2021.1957500

Dilatation of the Endolymphatic Space in the Ampulla of the Posterior Semicircular Canal: A New Clinical Finding Detected on Magnetic Resonance Imaging. Reviewed International journal

Masaru Morioka, Satofumi Sugimoto, Tadao Yoshida, Masaaki Teranishi, Masumi Kobayashi, Naoki Nishio, Naomi Katayama, Shinji Naganawa, Michihiko Sone

Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Vol. 42 ( 6 ) page： E643 - E647 2021.7

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVES: To investigate the clinical features of ears with dilatation of the endolymphatic space in the ampulla of the posterior semicircular canal on magnetic resonance imaging. STUDY DESIGN: Retrospective study. SETTING: A university hospital. METHODS: This study included 1,842 ears from 934 patients who underwent 3-T magnetic resonance imaging with gadolinium to investigate the presence of endolymphatic hydrops. Age, sex distribution, hearing thresholds on pure-tone audiometry, and vestibular symptoms were compared between cases of unilateral and bilateral dilatation of the endolymphatic space in the ampulla of the posterior semicircular canal. RESULTS: Forty-eight ears (17 men and 14 women; mean age 49.9 yrs) showed dilatation of the endolymphatic space in the ampulla of the posterior semicircular canal. Age and the rate of chronic sensorineural hearing loss were significantly higher in the unilateral group (14 ears) than in the bilateral group (34 ears). The average hearing thresholds and rates of vestibular symptoms reported did not differ between unilateral and bilateral cases, but some patients showed positional nystagmus. CONCLUSIONS: Dilatation of the endolymphatic space in the ampulla was observed selectively in the posterior semicircular canal, though its pathogenesis was not clear. Such dilatation is not usually accompanied by vestibular endolymphatic hydrops, and it may be a cause of vertigo and dizziness.

DOI： 10.1097/MAO.0000000000003073

【COVID-19肺炎と肺疾患AI開発のフロントライン】COVID-19肺炎におけるAI研究の動向および問題点について Reviewed

伊藤倫太郎, 岩野信吾, 長縄慎二

医用画像情報学会雑誌 Vol. 38 ( 2 ) page： 32 - 40 2021.7

Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：医用画像情報学会

COVID-19が世界中に広まり、COVID-19肺炎の診断に胸部CTや胸部単純X線の有用性が報告され、この画像所見を用いたAI開発が初期の段階から積極的に行われた。高性能なAIが多数存在するが、臨床において用いる際には注意すべき点が複数存在する。COVID-19肺炎に対して開発・使用された画像診断に関連するAI研究について、PubMedに2020年12月までに登録されたものを抽出しレビューを行った。

Novel Magnetic Resonance Imaging-Based Method for Accurate Diagnosis of Meniere's Disease Reviewed

Taeko Ito, Takashi Inoue, Hiroshi Inui, Toshiteru Miyasaka, Toshiaki Yamanaka, Kimihiko Kichikawa, Noriaki Takeda, Masato Kasahara, Tadashi Kitahara, Shinji Naganawa

Frontiers in Surgery Vol. 8 page： 671624 2021.6

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Frontiers Media SA

Background: Pathologically, Meniere's disease symptoms are considered to be associated with endolymphatic hydrops. Examinations revealing endolymphatic hydrops can be useful for accurate Meniere's disease diagnosis. We previously reported a quantitative method for evaluating endolymphatic hydrops, i.e., by measuring the volume of the endolymphatic space using three-dimensional magnetic resonance imaging (MRI) of the inner ear. This study aimed to confirm the usefulness of our methods for diagnosing Meniere's disease. Here, we extracted new explanatory factors for diagnosing Meniere's disease by comparing the volume of the endolymphatic space between healthy volunteers and patients with Meniere's disease. Additionally, we validated our method by comparing its diagnostic accuracy with that of the conventional method.

Methods and Findings: This is a prospective diagnostic accuracy study performed at vertigo/dizziness centre of our university hospital, a tertiary hospital. Eighty-six patients with definite unilateral Meniere's disease and 47 healthy volunteers (25 and 33 males, and 22 and 53 females in the control and patient groups, respectively) were enrolled. All participants underwent 3-Tesla MRI 4 h after intravenous injection of gadolinium to reveal the endolymphatic space. The volume of the endolymphatic space was measured and a model for Meniere's disease diagnosis was constructed and compared with models using conventional criteria to confirm the effectiveness of the methods used. The area under the receiver operating characteristic curve of the method proposed in this study was excellent (0.924), and significantly higher than that derived using the conventional criteria (0.877). The four indices, sensitivity, specificity, positive predictive value, and negative predictive value, were given at the threshold; all of these indices achieved higher scores for the 3D model compared to the 2D model. Cross-validation of the models revealed that the improvement was due to the incorporation of the semi-circular canals.

Conclusions: Our method showed high diagnostic accuracy for Meniere's disease. Additionally, we revealed the importance of observing the semi-circular canals for Meniere's disease diagnosis. The proposed method can contribute toward providing effective symptomatic relief in Meniere's disease.

DOI： 10.3389/fsurg.2021.671624

Age estimates from brain magnetic resonance images of children younger than two years of age using deep learning. Reviewed International journal

Masahiro Kawaguchi, Hiroyuki Kidokoro, Rintaro Ito, Anna Shiraki, Takeshi Suzuki, Yuki Maki, Masaharu Tanaka, Yoko Sakaguchi, Hiroyuki Yamamoto, Yosiyuki Takahashi, Shinji Naganawa, Jun Natsume

Magnetic resonance imaging Vol. 79 page： 38 - 44 2021.6

Language：English Publishing type：Research paper (scientific journal)

The accuracy of brain age estimates from magnetic resonance (MR) images has improved with the advent of deep learning artificial intelligence (AI) models. However, most previous studies on predicting age emphasized aging from childhood to adulthood and old age, and few studies have focused on early brain development in children younger than 2 years of age. Here, we performed brain age estimates based on MR images in children younger than 2 years of age using deep learning. Our AI model, developed with one slice each of raw T1- and T2-weighted images from each subject, estimated brain age with a mean absolute error of 8.2 weeks (1.9 months). The estimates of our AI model were close to those of human specialists. The AI model also estimated the brain age of subjects with a myelination delay as significantly younger than the chronological age. These results indicate that the prediction accuracy of our AI model approached that of human specialists and that our simple method requiring less data and preprocessing facilitates a radiological assessment of brain development, such as monitoring maturational changes in myelination.

DOI： 10.1016/j.mri.2021.03.004

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