Faculty Profiles - TAOKA Toshiaki

Papers - TAOKA Toshiaki

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Water Diffusivity Changes Along the Perivascular Space After Lumboperitoneal Shunt Surgery in Idiopathic Normal Pressure Hydrocephalus. International journal

Junko Kikuta, Koji Kamagata, Toshiaki Taoka, Kaito Takabayashi, Wataru Uchida, Yuya Saito, Christina Andica, Akihiko Wada, Kaito Kawamura, Chihiro Akiba, Madoka Nakajima, Masakazu Miyajima, Shinji Naganawa, Shigeki Aoki

Frontiers in neurology Vol. 13 page： 843883 - 843883 2022.2

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

Background: The aim of this study was to evaluate the water diffusivity changes along the perivascular space after lumboperitoneal shunt (LPS) surgery in idiopathic normal pressure hydrocephalus. Methods: Nine patients diagnosed with idiopathic normal pressure hydrocephalus (iNPH; three men and six women, mean age ± SD = 75.22 ± 5.12 years) according to the guidelines for iNPH in Japan were included in the study. Post-LPS surgery, six patients with iNPH who exhibited improvement in symptoms were defined as responder subjects, while three patients with iNPH who did not were defined as non-responder subjects. We calculated the mean analysis along the perivascular space (ALPS) index of the left and right hemispheres and compared the differences between pre- and post-LPS surgery mean ALPS indices in iNPH patients. In the responder or non-responder subjects, the mean ALPS indices in the pre- and post-operative iNPH groups were compared using Wilcoxon signed-rank tests. Next, correlation analyses between pre- and post-operation changes in the mean ALPS index and clinical characteristics were conducted. Results: The mean ALPS index of the post-operative iNPH group was significantly higher than that of the pre-operative iNPH group (p = 0.021). In responder subjects, the mean ALPS index of the post-operative iNPH group was significantly higher than that of the pre-operative iNPH group (p = 0.046). On the other hand, in the non-responder subjects, the mean ALPS index of the post-operative iNPH group was not significantly different compared to the pre-operative iNPH group (p = 0.285). The mean ALPS index change was not significantly correlated with changes in the Mini-Mental State Examination (MMSE) score (r = -0.218, p = 0.574), Frontal Assessment Battery (FAB) score (r = 0.185, p = 0.634), Trail Making Test A (TMTA) score (r = 0.250, p = 0.516), and Evans' index (r = 0.109, p = 0.780). In responder subjects, the mean ALPS index change was significantly correlated with Evans' index in pre-operative patients with iNPH (r = 0.841, p = 0.036). Conclusion: This study demonstrates the improved water diffusivity along perivascular space in patients with iNPH after LPS surgery. This could be indicative of glymphatic function recovery following LPS surgery.

DOI： 10.3389/fneur.2022.843883

＜Editors' Choice＞ Evaluation of system-related magnetic resonance imaging geometric distortion in radiation therapy treatment planning: two approaches and effectiveness of three-dimensional distortion correction.

Yutaka Kato, Kuniyasu Okudaira, Takeshi Kamomae, Motoki Kumagai, Youta Nagai, Toshiaki Taoka, Yoshiyuki Itoh, Shinji Naganawa

Nagoya journal of medical science Vol. 84 ( 1 ) page： 29 - 41 2022.2

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

We propose two methods to evaluate system-related distortion in magnetic resonance imaging (MRI) in radiation therapy treatment planning (RTP) and demonstrate the importance of three-dimensional (3D) distortion correction (DC) by quantitatively measuring the distortion magnitude. First, a small pin phantom was scanned at multiple positions using an external laser guide for accurate phantom placement and combined into one image encompassing a large area. Direct plane images were used for evaluating in-plane distortion and multiplanar reconstruction images for through-plane distortion with no DC, two-dimensional (2D) DC, and 3D DC. Second, a large grid sheet was scanned as the direct plane of the phantom placement. The distortion magnitude was determined by measuring the displacement between the MRI and reference coordinates. The measured distortions were compared between in- and through-plane when applying DC and between the two methods. The small pin phantom method can be used to evaluate a wide range of distortions, whereas data from the entire plane can be obtained with a single scan using the grid sheet without a laser guide. The mean distortion magnitudes differed between the methods. Furthermore, the 3D DC reduced in- and through-plane distortions. In conclusion, the small pin phantom method can be used to evaluate a wide range of distortions by creating a combined image, whereas the grid sheet method is simpler, accurate, repeatable, and does not require a special-order phantom or laser guide. As 3D DC reduces both in- and through-plane distortions, it can be used to improve RTP quality.

DOI： 10.18999/nagjms.84.1.29

特集 "-pathy"でせまる中枢神経疾患序説にかえて-umbrella term の意義とpenumbra

田岡俊昭

画像診断 Vol. 42 ( 2 ) page： 134 - 135 2022.1

特集 "-pathy"でせまる中枢神経疾患 CNS interstitial fluidopathy ─ 膜と水動態の異常

田岡俊昭

画像診断 Vol. 42 ( 2 ) page： 197 - 207 2022.1

Features from MRI texture analysis associated with survival outcomes in triple-negative breast cancer patients.

Saki Kamiya, Hiroko Satake, Yoko Hayashi, Satoko Ishigaki, Rintaro Ito, Mariko Kawamura, Toshiaki Taoka, Shingo Iwano, Shinji Naganawa

Breast cancer (Tokyo, Japan) Vol. 29 ( 1 ) page： 164 - 173 2022.1

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

PURPOSE: The purpose of the study is to evaluate the associations between intratumoral or peritumoral textural features derived from pretreatment magnetic resonance imaging (MRI) and recurrence-free survival (RFS) in triple-negative breast cancer (TNBC) patients. METHODS: Forty-three patients with TNBC who underwent preoperative MRI between February 2008 and March 2014 were included. We performed two-dimensional texture analysis on the intratumoral or peritumoral region of interest (ROI) on axial of T2-weighted image (T2WI), dynamic contrast-enhanced (DCE)-MRI and DCE-MRI subtraction images. We also analyzed histopathological data. Cox proportional hazards models were used to investigate associations with survival outcomes. RESULTS: Twelve of the 43 patients (27.9%) had recurrence disease, at a median of 32.5 months follow-up (1.4-61.5 months). In univariate analysis, nine texture features in T2WI and DCE-MRI subtraction images were significantly associated with RFS. In multivariate analysis, intratumoral difference entropy in DCE-MRI subtraction images in the initial phase (hazard ratio 11.71; 95% confidence interval (CI) [1.41, 97.00]; p value 0.023) and, peritumoral difference variance in DCE-MRI subtraction images in the delayed phase (hazard ratio 9.60; 95% CI [1.98, 46.51]; p value 0.005), were both independently associated with RFS. Moreover, multivariate analysis revealed the presence of lymphovascular invasion as independently associated with RFS (hazard ratio 8.13; 95% CI [2.16, 30.30]; p value 0.002). CONCLUSIONS: At pretreatment MRI, an intratumoral and peritumoral quantitative approach using texture analysis has the potential to serve as a prognostic marker in patients with TNBC.

DOI： 10.1007/s12282-021-01294-1

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

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.

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

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

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

MR Imaging of Endolymphatic Hydrops in Five Minutes.

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

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

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

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

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

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

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

特集撮った,読んだ,わかった! 認知症画像診断認知症画像のカッティングエッジ2:Glymphaticシステム,CNS interstitial fluidopathyの概念

田岡俊昭

画像診断 Vol. 41 ( 14 ) page： 1543 - 1553 2021.11

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. 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

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

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

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

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

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) Publisher：The Japan Neurosurgical Society

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

Neurofluid as Assessed by Diffusion-Weighted Imaging. International journal

Toshiaki Taoka

Magnetic resonance imaging clinics of North America Vol. 29 ( 2 ) page： 243 - 251 2021.5

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

The glymphatic system hypothesis is associated with the circulation of cerebrospinal fluid (CSF) in the skull and interstitial fluid (ISF) in the brain. There are several imaging techniques to visualize the dynamics of CSF and ISF. Magnetic resonance imaging (MRI) is one of the promising modalities for glymphatic imaging and diffusion MRI is expected imaging tool. Several disorders are associated with glymphatic dysfunction or impairment in the dynamics of CSF or ISF. The Central Nervous System interstitial fluidopathy concept has been proposed to encompass diseases with pathologies that are predominantly associated with abnormal ISF/CSF dynamics.

DOI： 10.1016/j.mric.2021.01.002

Associations among Cognitive Functions, Plasma DNA, and Diffusion Tensor Image along the Perivascular Space (DTI-ALPS) in Patients with Parkinson's Disease. International coauthorship International journal

Hsiu-Ling Chen, Pei-Chin Chen, Cheng-Hsien Lu, Nai-Wen Tsai, Chiun-Chieh Yu, Kun-Hsien Chou, Yun-Ru Lai, Toshiaki Taoka, Wei-Che Lin

Oxidative medicine and cellular longevity Vol. 2021 page： 4034509 - 4034509 2021.2

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

BACKGROUND: Parkinson's disease (PD) is a common neurodegenerative disease associated with accumulation of misfolding proteins and increased neuroinflammation, which may further impair the glymphatic system. The purpose of this study was to utilize diffusion tensor image analysis along the perivascular space (DTI-ALPS) to evaluate glymphatic system activity and its relationship with systemic oxidative stress status in PD patients. METHODS: Magnetic resonance imaging and neuropsychological tests were conducted on 25 PD patients with normal cognition (PDN), 25 PD patients with mild cognitive impairment (PD-MCI), 38 PD patients with dementia (PDD), and 47 normal controls (NC). Oxidative stress status was assessed by plasma DNA level. Differences in ALPS-index among the subgroups were assessed and further correlated with cognitive functions and plasma DNA levels. RESULTS: The PD-MCI and PDD groups showed significantly lower ALPS-index compared to normal controls. The ALPS-index was inversely correlated with plasma nuclear DNA, mitochondrial DNA levels, and cognitive scores. CONCLUSIONS: Lower diffusivity along the perivascular space, represented by lower ALPS-index, indicates impairment of the glymphatic system in PD patients. The correlation between elevated plasma nuclear DNA levels and lower ALPS-index supports the notion that PD patients may exhibit increased oxidative stress associated with glymphatic system microstructural alterations.

DOI： 10.1155/2021/4034509

ISMRM2020における富樫かおり先生のGold Medal受賞と長縄慎二先生のSenior Fellow選出を記念して

黒田輝, 小畠隆行, 三木幸雄, 田岡俊昭

日本磁気共鳴医学会雑誌 Vol. 41 ( 1 ) page： 1 - 4 2021.2

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：日本磁気共鳴医学会

<p>　2020年8月にウェブ開催されたISMRM（国際磁気共鳴医学会）において，京都大学の富樫かおり先生がGold Medalを受賞され，名古屋大学の長縄慎二先生がSenior Fellowに選出されました．同じ年の大会で日本人が同時に2名選出されることは初めてのことであり，MRI研究における日本の大きなプレゼンスを示す出来事でもありました．</p><p>　この度，この快挙を記念して，お二人とご縁の深い先生方からの特別寄稿をいただきましたので，ここに掲載させて頂きます．</p>

DOI： 10.2463/jjmrm.2020-1724

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

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

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

PURPOSE: Decrease in signal of the cerebrospinal fluid (CSF) on low b-value diffusion weighted image (DWI) due to non-uniform flow can provide additional information regarding CSF motion. The purpose of the current study was to evaluate whether arterial pulsations constitute the driving force of CSF motion. METHODS: We evaluated the CSF signals within the Sylvian fissure on low b-value DWI in 19 patients with unilateral middle cerebral artery (MCA) occlusion. DWI with b-value of 500 s/mm2 was evaluated for a decrease in CSF signal within the Sylvian fissure including the Sylvian vallecula and lower, middle, and higher Sylvian fissures and graded as follows: the same as contralateral side; smaller signal decrease than that on contralateral side; and no signal decrease. MR angiography (MRA) findings of MCA were graded as follows: the same as contralateral, lower signal than contralateral signal, and no signal. In 15 patients, regional cerebral blood flow (rCBF) was evaluated using single-photon emission computed tomography (SPECT) studies and graded as >90%, 90%-70%, and <70% rCBF compared to contralateral. The correlations between the gradings were evaluated using G likelihood-ratio test. RESULTS: There was no statistically significant correlation between the MRA and low b-value DWI gradings of CSF in all areas. There were statistically significant correlations between the decreases in CBF on SPECT and CSF signals in the middle Sylvian fissure. CONCLUSION: The driving force of CSF pulsation in the Sylvian sinus may be related to the pulsations of the cerebral hemisphere rather than direct arterial pulsations.

DOI： 10.2463/mrms.mp.2020-0121

Relationship between Time-dependent Signal Changes in Parasagittal Perivenous Cysts and Leakage of Gadolinium-based Contrast Agents into the Subarachnoid Space.

Shinji Naganawa, Rintaro Ito, Rei Nakamichi, 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. 20 ( 4 ) page： 378 - 384 2021

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

PURPOSE: To investigate the association between signal changes over time in perivenous cystic structures near the superior sagittal sinus and leakage of a gadolinium-based contrast agent (GBCA) into the subarachnoid space in patients with suspected endolymphatic hydrops. METHODS: Fifty-one cystic structures in 27 cases were evaluated. The signal intensity of the cystic structures was measured on 3D real inversion recovery (3D-real IR) images obtained at pre-, and at 10 min, 4 hrs and 24 hrs post-intravenous administration (IV) of GBCA. Signal enhancement of the cystic structures from the pre-contrast images at each time point was compared in subjects with leakage (positive) versus those without leakage (negative) using an ANOVA. Fisher's exact probability test was used to compare the maximum contrast-enhanced time point between positive and negative groups. We used 5% as a threshold to determine statistical significance. RESULTS: In leakage positive subjects, mean signal enhancement of the cysts was significantly greater at 4 and 24 hrs compared to 10 min. However, although there was a trend of an increase from 4 to 24 hrs, the difference was not significant. In the leakage negative group, mean signal enhancement of the cysts was significantly higher at 4 hrs compared to 10 min and 24 hrs. There was no significant difference between 10 min and 24 hrs. In the positive group, the maximum signal increase was found in 10/38 and 28/38 cysts at 4 and 24 hrs after IV-GBCA, respectively. In the leakage negative group, the maximum signal increase was found in 10/13 and 3/13 cysts at 4 and 24 hrs, respectively (P = 0.0019). CONCLUSION: There was an association between signal changes over time after IV-GBCA in perivenous cystic structures and leakage of GBCA. Further research to clarify the impact of cystic structures on the function of the waste clearance system of the brain is warranted.

DOI： 10.2463/mrms.mp.2020-0138

Relationship between Parasagittal Perivenous Cysts and Leakage of Gadolinium-based Contrast Agents into the Subarachnoid Space around the Cortical Veins after Intravenous Administration. Reviewed

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

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 3 ) page： 245 - 252 2021

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

PURPOSE: The purpose of this retrospective study was to investigate the relationship between the number and size of cystic structures around the cortical veins near the superior sagittal sinus and the leakage of gadolinium-based contrast agent (GBCA) around the cortical veins. METHODS: Of 190 patients (91 male and 99 female), that were scanned at 4 h after an intravenous injection of GBCA as a diagnostic examination for endolymphatic hydrops, 6 patients with GBCA leakage were younger than the previously proposed threshold age of 37.3 years for leakage. Six age-matched patients without leakage were also included for reference. In addition, we included 8 cases without leakage that were older than the hypothesized threshold of 37.3 years, as well as 8 age-matched patients with GBCA leakage into the cerebrospinal fluid space. The number of cysts was counted and the sizes were measured in these 28 patients (age: 32-60 years old, 13 men and 15 women). RESULTS: The mean number of cysts surrounding the cortical veins in the parasagittal region was 4.29 ± 1.77 vs. 1.79 ± 1.05 (P = 0.0001) in the subjects with and without GBCA leakage, respectively. The mean size of the largest cysts was at 8.89 ± 3.49 mm vs. 5.69 ± 2.29 (P = 0.009) in the subjects with and without GBCA leakage, respectively. CONCLUSION: The number and size of the perivenous cystic structures near the superior sagittal sinus is greater in subjects with GBCA leakage into the subarachnoid space compared with those without leakage. Future research regarding the histological and functional details of these parasagittal cystic structures is needed.

DOI： 10.2463/mrms.mp.2020-0062

Intracranial Distribution of Intravenously Administered Gadolinium-based Contrast Agent over a Period of 24 Hours: Evaluation with 3D-real IR Imaging and MR Fingerprinting. Reviewed

Shinji Naganawa, Rintaro Ito, Yutaka Kato, Hisashi Kawai, Toshiaki Taoka, Tadao Yoshida, Katsuya Maruyama, Katsutoshi Murata, Gregor Körzdörfer, Josef Pfeuffer, Mathias Nittka, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 20 ( 1 ) page： 91 - 98 2021

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

PURPOSE: To evaluate the feasibility for the detection of slight contrast effects after intravenous administration of single dose gadolinium-based contrast agent (IV-SD-GBCA), the time course of the GBCA distribution up to 24 h was examined in various fluid spaces and brain parenchyma using 3D-real IR imaging and MR fingerprinting (MRF). METHODS: Twenty-four patients with a suspicion of endolymphatic hydrops were scanned at pre-administration and at 10 min, 4 and 24 h post-IV-SD-GBCA. 3D-real IR images and MRF at the level of the internal auditory canal were obtained. The signal intensity on the 3D-real IR image of the cerebrospinal fluid (CSF) in the cerebellopontine angle cistern (CPA), Sylvian fissure (Syl), lateral ventricle (LV), and cochlear perilymph (CPL) was measured. The T1 and T2 values of cerebellar gray (GM) and white matter (WM) were measured using MRF. Each averaged value at the various time points was compared using an analysis of variance. RESULTS: The signal intensity on the 3D-real IR image in each CSF region peaked at 4 h, and was decreased significantly by 24 h (P< 0.05). All patients had a maximum signal intensity at 4 h in the CPA, and Syl. The mean CPL signal intensity peaked at 4 h and decreased significantly by 24 h (P < 0.05). All patients but two had a maximum signal intensity at 4 h. Regarding the T1 value in the cerebellar WM and GM, the T1 value at 10 min post-IV-GBCA was significantly decreased compared to the pre-contrast scan, but no significant difference was observed at the other time points. There was no significant change in T2 in the gray or white matter at any of the time points. CONCLUSION: Time course of GBCA after IV-SD-GBCA could be evaluated by 3D-real IR imaging in CSF spaces and in the brain by MRF.

DOI： 10.2463/mrms.mp.2020-0030

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