研究者詳細 - 菅　博人

論文 - 菅　博人

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Machine learning trained with quantitative susceptibility mapping to detect mild cognitive impairment in Parkinson's disease.

Shibata H, Uchida Y, Inui S, Kan H, Sakurai K, Oishi N, Ueki Y, Oishi K, Matsukawa N

Parkinsonism & related disorders 94 巻頁： 104 - 110 2022年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Parkinsonism and Related Disorders

Background: Cognitive decline is commonly observed in Parkinson's disease (PD). Identifying PD with mild cognitive impairment (PD-MCI) is crucial for early initiation of therapeutic interventions and preventing cognitive decline. Objective: We aimed to develop a machine learning model trained with magnetic susceptibility values based on the multi-atlas label-fusion method to classify PD without dementia into PD-MCI and normal cognition (PD-CN). Methods: This multicenter observational cohort study retrospectively reviewed 61 PD-MCI and 59 PD-CN cases for the internal validation cohort and 22 PD-MCI and 21 PD-CN cases for the external validation cohort. The multi-atlas method parcellated the quantitative susceptibility mapping (QSM) images into 20 regions of interest and extracted QSM-based magnetic susceptibility values. Random forest, extreme gradient boosting, and light gradient boosting were selected as machine learning algorithms. Results: All classifiers demonstrated substantial performances in the classification task, particularly the random forest model. The accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve for this model were 79.1%, 77.3%, 81.0%, and 0.78, respectively. The QSM values in the caudate nucleus, which were important features, were inversely correlated with the Montreal Cognitive Assessment scores (right caudate nucleus: r = −0.573, 95% CI: −0.801 to −0.298, p = 0.003; left caudate nucleus: r = −0.659, 95% CI: −0.894 to −0.392, p < 0.001). Conclusions: Machine learning models trained with QSM values successfully classified PD without dementia into PD-MCI and PD-CN groups, suggesting the potential of QSM values as an auxiliary biomarker for early evaluation of cognitive decline in patients with PD.

DOI： 10.1016/j.parkreldis.2021.12.004

Penumbra Detection With Oxygen Extraction Fraction Using Magnetic Susceptibility in Patients With Acute Ischemic Stroke.

Uchida Y, Kan H, Inoue H, Oomura M, Shibata H, Kano Y, Kuno T, Usami T, Takada K, Yamada K, Kudo K, Matsukawa N

Frontiers in neurology 13 巻頁： 752450 2022年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Neurology

Background: The oxygen extraction fraction (OEF) has been applied to identify ischemic penumbral tissue, but is difficult to use in an urgent care setting. This study aimed to investigate whether an OEF map generated via magnetic resonance quantitative susceptibility mapping (QSM) could help identify the ischemic penumbra in patients with acute ischemic stroke. Materials and Methods: This prospective imaging study included 21 patients with large anterior circulation vessel occlusion who were admitted <24 h after stroke onset and 21 age-matched healthy controls. We identified the ischemic penumbra as the region with a Tmax of >6 s during dynamic susceptibility contrast-magnetic resonance imaging (DSC-MRI) and calculated the perfusion-core mismatch ratio between the ischemic penumbra and infarct core volumes. The OEF values were measured based on magnetic susceptibility differences between the venous structures and brain tissues using rapid QSM acquisition. Volumes with increased OEF values were compared to the ischemic penumbra volumes using an anatomical template. Results: Eleven patients had a perfusion-core mismatch ratio of ≥1.8, and reperfusion therapy was recommended. In these patients, the volumes with increased OEF values of >51.5%, which was defined using the anterior circulation territory OEF values from the 21 healthy controls, were positively correlated with the ischemic penumbra volumes (r = 0.636, 95% CI: 0.059 to 0.895, P = 0.035) and inversely correlated with the 30-day change in the National Institutes of Health Stroke Scale scores (r = −0.624, 95% CI: −0.891 to −0.039, P = 0.041). Conclusion: Tissue volumes with increased OEF values could predict ischemic penumbra volumes based on DSC-MRI, highlighting the potential of the QSM-derived OEF map as a penumbra biomarker to guide treatment selection in patients with acute ischemic stroke.

DOI： 10.3389/fneur.2022.752450

R2* relaxometry analysis for mapping of white matter alteration in Parkinson's disease with mild cognitive impairment. 国際誌

Kan H, Uchida Y, Ueki Y, Arai N, Tsubokura S, Kunitomo H, Kasai H, Aoyama K, Matsukawa N, Shibamoto Y

NeuroImage. Clinical 33 巻頁： 102938 - 102938 2022年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NeuroImage: Clinical

Background: R2* relaxometry analysis combined with quantitative susceptibility mapping (QSM), which has high sensitivity to iron deposition, can distinguish microstructural changes of the white matter (WM) and iron deposition, thereby providing a sensitive and biologically specific measure of the WM owing to the changes in myelin and its surrounding environment. This study aimed to explore the microstructural WM alterations associated with cognitive impairment in patients with Parkinson's disease (PD) using R2* relaxometry analysis combined with QSM. Materials and methods: We enrolled 24 patients with PD and mild cognitive impairment (PD-MCI), 22 patients with PD and normal cognition (PD-CN), and 19 age- and sex-matched healthy controls (HC). All participants underwent Montreal Cognitive Assessment (MoCA) and brain magnetic resonance imaging, including structural three-dimensional T1-weighted images and multiple spoiled gradient echo sequence (mGRE). The R2* and susceptibility maps were estimated from the multiple magnitude images of mGRE. The susceptibility maps were used for verifying iron deposition in the WM. The voxel-based R2* of the entire WM and its correlation with cognitive performance were analyzed. Results: In the voxel-based group comparisons, the R2* in the PD-MCI group was lower in some WM regions, including the corpus callosum, than R2* in the PD-CN and HC groups. The mean susceptibility values in almost all brain regions were negative and close-to-zero values, indicating no detectable paramagnetic iron deposition in the WM of all subjects. There was a significant positive correlation between R2* and MoCA in some regions of the WM, mainly the corpus callosum and left hemisphere. Conclusion: R2* relaxometry analysis for WM microstructural changes provided further biologic insights on demyelination and changes in the surrounding environment, supported by the QSM results demonstrating no iron existence. This analysis highlighted the potential for the early evaluation of cognitive decline in patients with PD.

DOI： 10.1016/j.nicl.2022.102938

Quantitative susceptibility mapping as an imaging biomarker for Alzheimer's disease: The expectations and limitations.

Uchida Y, Kan H, Sakurai K, Oishi K, Matsukawa N

Frontiers in neuroscience 16 巻頁： 938092 2022年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Neuroscience

Alzheimer’s disease (AD) is the most common type of dementia and a distressing diagnosis for individuals and caregivers. Researchers and clinical trials have mainly focused on β-amyloid plaques, which are hypothesized to be one of the most important factors for neurodegeneration in AD. Meanwhile, recent clinicopathological and radiological studies have shown closer associations of tau pathology rather than β-amyloid pathology with the onset and progression of Alzheimer’s symptoms. Toward a biological definition of biomarker-based research framework for AD, the 2018 National Institute on Aging–Alzheimer’s Association working group has updated the ATN classification system for stratifying disease status in accordance with relevant pathological biomarker profiles, such as cerebral β-amyloid deposition, hyperphosphorylated tau, and neurodegeneration. In addition, altered iron metabolism has been considered to interact with abnormal proteins related to AD pathology thorough generating oxidative stress, as some prior histochemical and histopathological studies supported this iron-mediated pathomechanism. Quantitative susceptibility mapping (QSM) has recently become more popular as a non-invasive magnetic resonance technique to quantify local tissue susceptibility with high spatial resolution, which is sensitive to the presence of iron. The association of cerebral susceptibility values with other pathological biomarkers for AD has been investigated using various QSM techniques; however, direct evidence of these associations remains elusive. In this review, we first briefly describe the principles of QSM. Second, we focus on a large variety of QSM applications, ranging from common applications, such as cerebral iron deposition, to more recent applications, such as the assessment of impaired myelination, quantification of venous oxygen saturation, and measurement of blood– brain barrier function in clinical settings for AD. Third, we mention the relationships among QSM, established biomarkers, and cognitive performance in AD. Finally, we discuss the role of QSM as an imaging biomarker as well as the expectations and limitations of clinically useful diagnostic and therapeutic implications for AD.

DOI： 10.3389/fnins.2022.938092

Effects of a new speech support application on intensive speech therapy and changes in functional brain connectivity in patients with post-stroke aphasia.

Katsuno Y, Ueki Y, Ito K, Murakami S, Aoyama K, Oishi N, Kan H, Matsukawa N, Nagao K, Tatsumi H

Frontiers in human neuroscience 16 巻頁： 870733 2022年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Human Neuroscience

Aphasia is a language disorder that occurs after a stroke and impairs listening, speaking, reading, writing, and calculation skills. Patients with post-stroke aphasia in Japan are increasing due to population aging and the advancement of medical treatment. Opportunities for adequate speech therapy in chronic stroke are limited due to time constraints. Recent studies have reported that intensive speech therapy for a short period of time or continuous speech therapy using high-tech equipment, including speech applications (apps, can improve aphasia even in the chronic stage. However, its underlying mechanism for improving language function and its effect on other cognitive functions remains unclear. In the present study, we investigated whether intensive speech therapy using a newly developed speech support app could improve aphasia and other cognitive functions in patients with chronic stroke. Furthermore, we examined whether it can alter the brain network related to language and other cortical areas. Thus, we conducted a prospective, single-comparison study to examine the effects of a new speech support app on language and cognitive functions and used resting state functional MRI (rs-fMRI) regions of interest (ROI) to ROI analysis to determine changes in the related brain network. Two patients with chronic stroke participated in this study. They used the independent speech therapy system to perform eight sets of 20 randomly presented words/time (taking approximately 20 min), for 8 consecutive weeks. Their language, higher cognitive functions including attention function, and rs-fMRI, were evaluated before and after the rehabilitation intervention using the speech support app. Both patients had improved pronunciation, daily conversational situations, and attention. The rs-fMRI analysis showed increased functional connectivity of brain regions associated with language and attention related areas. Our results show that intensive speech therapy using this speech support app can improve language and attention functions even in the chronic stage of stroke, and may be a useful tool for patients with aphasia. In the future, we will conduct longitudinal studies with larger numbers of patients, which we hope will continue the trends seen in the current study, and provide even stronger evidence for the usefulness of this new speech support app.

DOI： 10.3389/fnhum.2022.870733

T-staging of rectal cancer: Utility of single-shot turbo spin-echo diffusion-weighted imaging with T2-weighted images and fusion images.

Ogawa M, Urano M, Takaishi T, Kan H, Arai N, Takahashi H, Hara M, Saito M, Shibamoto Y

PloS one 16 巻 ( 4 ) 頁： e0249433 2021年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PLoS ONE

Purpose The purpose of this study was to evaluate the usefulness of turbo spin-echo (TSE) DWI with fusion images in the T-staging compared with T2-weighted imaging (T2WI) alone and conventional echo-planner imaging (EPI) DWI. Methods In this prospective study, 4-mm-thick axial EPI-DWI, TSE-DWI, and T2WI were performed with the same slice locations for 20 patients with rectal cancer. Fusion images of DWI and T2WI were created for both EPI-DWI and TSE-DWI. Ten readers independently diagnosed the T-stages and scored the degree of confidence referring to T2WI alone and then to DWI, T2WI, and fusion images (DWI+T2WI) for each EPI-DWI and TSE-DWI. Visual score assessments of image quality were performed for each DWI. Results Inter-observer agreement of T-staging for 10 readers was slight on T2WI alone but fair on EPI-DWI+T2WI and excellent on TSE-DWI+T2WI images. No readers gave higher confidence scores for T2WI compared to EPI/TSE-DWI+T2WI and for EPI-DWI+T2WI compared to TSE-DWI+T2WI. In seven pathologically-proven cases, poor, poor to slight, and fair to perfect agreements with the pathological T-stage were observed with T2WI alone, EPI-DWI +T2WI, and TSE-DWI+T2WI, respectively. All readers gave higher scores regarding image distortion and lower scores regarding image noise for TSE-DWI compared to EPI-DWI. For DWI utility, higher scores were assigned for TSE-DWI compared to EPI-DWI in 7 readers and there were no significant differences in the other 3 readers. Conclusion TSE-DWI images might be more appropriate for image fusion with T2WI and rectal cancer T-staging compared with EPI-DWI and T2WI alone.

DOI： 10.1371/journal.pone.0249433

Arai N., Kan H.

American Journal of Neuroradiology 41 巻 ( 4 ) 頁： E21 - E21 2020年4月

Changes in Apparent Diffusion Coefficient (ADC) during Cardiac Cycle of the Brain in Idiopathic Normal Pressure Hydrocephalus Before and After Cerebrospinal Fluid Drainage. 国際誌

Osawa T, Ohno N, Mase M, Miyati T, Omasa R, Ishida S, Kan H, Arai N, Kasai H, Shibamoto Y, Kobayashi S, Gabata T

Journal of magnetic resonance imaging : JMRI 53 巻 ( 4 ) 頁： 1200 - 1207 2021年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Magnetic Resonance Imaging

Background: The causative mechanisms of idiopathic normal-pressure hydrocephalus (iNPH) symptoms are currently unknown. Purpose: To assess the dynamic changes in the apparent diffusion coefficient (ADC) during the cardiac cycle (ΔADC) of the brain before and after the lumbar tap and shunt surgery for the purpose of determining changes in hydrodynamic and biomechanical properties in the brain after cerebrospinal fluid (CSF) drainage for iNPH. Study Type: Retrospective. Subjects: Overall, 22 patients suspected to have iNPH were examined before and after the lumbar tap and were divided into patients who showed symptomatic improvements (positive group, n = 17) and those without improvement (negative group, n = 5) after the lumbar tap. Seven patients in the positive group were examined after the shunt surgery. Field Strength/Sequence: 1.5T, electrocardiographically synchronized single-shot diffusion echo-planar imaging. Assessment: The frontal white matter ΔADC and mean ADC (ADCmean) were compared between before and 24 hours after lumbar tap and from 1 week to 1 month after the shunt surgery. Statistical Tests: Wilcoxon signed-rank test was used. P < 0.05 was considered statistically significant. Results: The ΔADC after the lumbar tap in the positive group was significantly lower than that before (P < 0.05), whereas no significant difference was found in the negative group (P = 0.23). After the lumbar tap, ΔADC decreased in 16 of 17 patients in the positive group, whereas ADCmean did not significantly change (P = 0.96). After the shunt surgery, ΔADC decreased in all seven patients (P < 0.05), whereas ADCmean did not significantly change (P = 0.87). Data Conclusion: The frontal white matter ΔADC in iNPH decreased after the lumbar tap and shunt surgery. ΔADC analysis may provide detailed information regarding changes in the hydrodynamic and biomechanical properties through CSF drainage. Level of Evidence: 4. Technical Efficacy Stage: 4.

DOI： 10.1002/jmri.27412

Evaluation of Thin-slice Coronal Single-shot Turbo Spin-echo Diffusion-weighted Imaging of the Hand: A Comparison with Conventional Echo-planar Diffusion-weighted Imaging.

Ogawa M, Nakagawa M, Arai N, Kan H, Ohba S, Shibata S, Maki H, Shibamoto Y

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine 19 巻 ( 4 ) 頁： 382 - 388 2020年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Magnetic Resonance in Medical Sciences

We prospectively evaluated thin-slice coronal turbo spin-echo (TSE) diffusion-weighted imaging (DWI) covering a larger area with the recently-developed techniques on a 3T MRI scanner, compared with echo-planar imaging (EPI)-DWI in patients undergoing routine hand MRI. Visual score assessment and apparent diffusion coefficient (ADC) measurement were performed for patients with suspected hand tumors. TSE-DWI was superior to EPI-DWI, with less image distortion. The visual score and ADC comparison assessments proved that the image noise of TSE-DWI was acceptable.

DOI： 10.2463/mrms.tn-2019-0115

Decreasing iron susceptibility with temperature in quantitative susceptibility mapping: A phantom study. 国際誌

Kan H, Uchida Y, Arai N, Takizawa M, Miyati T, Kunitomo H, Kasai H, Shibamoto Y

Magnetic resonance imaging 73 巻頁： 55 - 61 2020年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Magnetic Resonance Imaging

To clarify the temperature dependence of susceptibility estimated by quantitative susceptibility mapping (QSM) analysis, we investigated the relationship between temperature and susceptibility using a cylinder phantom with varying temperatures. Six solutions with various concentrations of superparamagnetic iron oxide (SPIO) nanoparticles were employed. These tubes were placed in a cylinder phantom and surrounded with water. The temperature of the circulated water was adjusted to change the temperature in the cylinder phantom from 25.8 °C to 42.5 °C. The cylinder phantom was scanned via a three-dimensional multiple spoiled gradient-echo sequence for R2* and QSM analyses with varying temperatures. The relationships between temperature, susceptibility, and R2* values were determined. Moreover, the temperature coefficients of susceptibility (χ-Tc) and (R2*-Tc) were calculated at each concentration and the linearities in these indices against each SPIO concentration were validated. Significant inverse correlations were found between temperature, susceptibility, and R2* values at each SPIO concentration due to the decrease in paramagnetic iron susceptibility that occurred with increasing temperature based on Curie's law. Moreover, although there were significant correlations between the susceptibility and R2* values at any temperature, the slopes of the regression lines grew in height with greater temperatures. The percentage of difference per Celsius degree in susceptibility in any SPIO concentration was lower than the corresponding finding among the R2* results. There were strong linearities between the SPIO concentration, χ-Tc (r = −0.994; p < 0.001), and R2*-Tc (r = −0.998; p < 0.001). The χ-Tc and R2*-Tc outcomes in a particular voxel varied considerably with the iron contents. Although there was an inverse correlation noted between temperature and susceptibility, the susceptibility analysis showed smaller temperature dependence relative to the R2* analysis. QSM analysis might be a more suitable option for magnetic resonance-based iron quantification in comparison with R2* relaxometry.

DOI： 10.1016/j.mri.2020.08.012

Iron leakage owing to blood-brain barrier disruption in small vessel disease CADASIL. 国際誌

Uchida Y, Kan H, Sakurai K, Arai N, Inui S, Kobayashi S, Kato D, Ueki Y, Matsukawa N

Neurology 95 巻 ( 9 ) 頁： e1188 - e1198 2020年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Neurology

ObjectiveTo assess the relationship among iron accumulation, blood-brain barrier (BBB) damage, and cognitive function in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).MethodsWe enrolled 21 patients with NOTCH3 mutations and 21 age-matched healthy controls in this cross-sectional study. All participants underwent global physical and cognitive assessments and brain MRI using voxel-based quantitative susceptibility mapping (QSM; iron deposition measure) and dynamic contrast-enhanced MRI (BBB permeability measure). We compared behavioral and imaging data between the groups and analyzed the correlations in each group.ResultsAmong 21 NOTCH3 mutation carriers, 10 were symptomatic and 11 asymptomatic. Montreal Cognitive Assessment scores were significantly different among the groups (symptomatic < asymptomatic < control participants). Voxel-based QSM analysis revealed that the symptomatic group had higher QSM values than did the asymptomatic group in the putamen, caudate nucleus, temporal pole, and centrum semiovale. These QSM values were positively correlated with regional BBB permeabilities (putamen: r = 0.57, p = 0.006; caudate nucleus: r = 0.51, p = 0.019; temporal pole: r = 0.48, p = 0.030; centrum semiovale: r = 0.45, p = 0.044) and negatively correlated with Montreal Cognitive Assessment scores (caudate nucleus: r = -0.53, p = 0.012; temporal pole: r = -0.56, p = 0.008).ConclusionsThis study showed that cerebral iron burden was associated with regional BBB permeability and cognitive dysfunction in patients with CADASIL, highlighting the potential of these imaging techniques as auxiliary biomarkers to monitor the course of small vessel disease.

DOI： 10.1212/WNL.0000000000010148

Magnetic Susceptibility Associates With Dopaminergic Deficits and Cognition in Parkinson's Disease. 国際誌

Uchida Y, Kan H, Sakurai K, Inui S, Kobayashi S, Akagawa Y, Shibuya K, Ueki Y, Matsukawa N

Movement disorders : official journal of the Movement Disorder Society 35 巻 ( 8 ) 頁： 1396 - 1405 2020年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Movement Disorders

Objective: The objective of this study was to assess the relationship between nigrostriatal magnetic susceptibility and dopamine transporter abnormality and their associations with behavioral and cognitive impairments in patients with Parkinson's disease (PD). Methods: For this case-control study, we enrolled 41 patients with PD and 20 age-matched healthy controls. All participants underwent global physical and cognitive assessments, 3-Tesla brain magnetic resonance imaging including quantitative susceptibility mapping (QSM; iron deposition measure), and 123I-N-v-fluoropropyl-2b-carbomethoxy-3b-(4-iodophenyl) nortropane single-photon emission computed tomography (dopamine transporter measure). We subdivided the striatum into the putamen, caudate nucleus, and nucleus accumbens and measured the nigrostriatal QSM values and dopamine transporter–specific binding ratios using an atlas-based approach. Results: The patients with PD had higher QSM values in the substantia nigra and subdivisions of the striatum than did the healthy controls. The striatal dopamine transporter–specific binding ratios were not correlated with the QSM values of the substantia nigra but were inversely correlated with those of the striatum (putamen, r = −0.478, P = 0.009; caudate nucleus, r = −0.462, P = 0.011). The QSM values of the putamen were positively correlated with motor parkinsonism scores (Movement Disorder Society Unified Parkinson's Disease Rating Scale, r = 0.505, P = 0.003), and those of the caudate nucleus were negatively correlated with cognitive impairment scores (Montreal Cognitive Assessment, r = −0.525, P < 0.001). Conclusions: This study showed that striatal iron accumulations were correlated with dopaminergic deficits and neurophysiological signs in patients with PD, highlighting the potential of QSM as an auxiliary biomarker for parkinsonism and cognitive dysfunction. © 2020 International Parkinson and Movement Disorder Society.

DOI： 10.1002/mds.28077

Simultaneous voxel-based magnetic susceptibility and morphometry analysis using magnetization-prepared spoiled turbo multiple gradient echo.

Kan H, Uchida Y, Arai N, Ueki Y, Aoki T, Kasai H, Kunitomo H, Hirose Y, Matsukawa N, Shibamoto Y

NMR in biomedicine 33 巻 ( 5 ) 頁： e4272 2020年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NMR in Biomedicine

This study aimed to develop and test a simultaneous acquisition and analysis pipeline for voxel-based magnetic susceptibility and morphometry (VBMSM) on a single dataset using young volunteers, elderly healthy volunteers, and an Alzheimer's disease (AD) group. 3D T1-weighted and multi-echo phase images for VBM and quantitative susceptibility mapping (QSM) were simultaneously acquired using a magnetization-prepared spoiled turbo multiple gradient echo sequence with inversion pulse for QSM (MP-QSM). The magnitude image was split into gray matter (GM) and white matter (WM) and was spatially normalized. The susceptibility map was reconstructed from the phase images. The segmented image and susceptibility map were compared with those obtained from conventional multiple spoiled gradient echo (mGRE) and MP-spoiled gradient echo (MP-GRE) in healthy volunteers to validate the availability of MP-QSM by numerical measurements. To assess the feasibility of the VBMSM analysis pipeline, voxel-based comparisons of susceptibility and morphometry in MP-QSM were conducted in volunteers with a bimodal age distribution, and in elderly volunteers and the AD group, using spatially normalized GM and WM volume images and a susceptibility map. GM/WM contrasts in MP-QSM, MP-GRE, and mGRE were 0.14 ± 0.011, 0.17 ± 0.015, and 0.045 ± 0.010, respectively. Segmented GM and WM volumes in the MP-QSM closely coincided with those in the MP-GRE. Region of interest analyses indicated that the mean susceptibility values in MP-QSM were completely in agreement with those in mGRE. In an evaluation of the aging effect, a significant increase and decrease in susceptibility and volume were found by VBMSM in deep GM and WM, respectively. Between the elderly volunteers and the AD group, the characteristic susceptibility and volume changes in GM and WM were observed. The proposed MP-QSM sequence makes it possible to acquire acceptable-quality images for simultaneous analysis and determine brain atrophy and susceptibility distribution without image registration by using voxel-based analyses.

DOI： 10.1002/nbm.4272

Visualization of Nigrosome 1 from the Viewpoint of Anatomic Structure

Arai N., Kan H., Ogawa M., Uchida Y., Takizawa M., Omori K., Miyati T., Kasai H., Kunitomo H., Shibamoto Y.

AMERICAN JOURNAL OF NEURORADIOLOGY 41 巻 ( 1 ) 頁： 86 - 91 2020年1月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：American Journal of Neuroradiology

BACKGROUND AND PURPOSE: Parkinson disease is related to neurodegeneration and iron deposition in the substantia nigra pars compacta and nigrosome 1. However, visualization of nigrosome 1 via MR imaging is poor owing to the bilateral asymmetry, regardless of whether it is healthy. We focused on the magic angle and susceptibility effect and evaluated the anatomic slant structure of nigrosome 1 by tilting subjects’ heads in the B0 direction. MATERIALS AND METHODS: To investigate the effectiveness of the magic angle, we tilted the volunteers’ heads to the right and left in the B0 direction or not at all for evaluating correlations between the degree of head tilting and visualization of the right nigrosome 1 and left nigrosome 1 using 3D spoiled gradient-echo sequences with multiecho acquisitions. We evaluated the susceptibility of nigrosome 1 and the local field using quantitative susceptibility mapping to assess static magnetic field inhomogeneity. RESULTS: The heads tilted to the right and left showed significantly higher contrasts of nigrosome 1 and the substantia nigra pars compacta than the nontilted heads. No significant differences were observed in the visualization and susceptibility between the right nigrosome 1 and left nigrosome 1 for each head tilt. The effect of the magic angle was remarkable in the nontilted heads. This finding was supported by quantitative susceptibility mapping because the anatomic slant structure of nigrosome 1 was coherent between the axis of nigrosome 1 and the magic angle. CONCLUSIONS: The asymmetric visualization of nigrosome 1 is affected by the magic angle and susceptibility. The anatomic slant structure of nigrosome 1 causes these challenges in visualization.

DOI： 10.3174/ajnr.A6338

Improvement of Signal Inhomogeneity Induced by Radio-frequency Transmit-related Phase Error for Single-step Quantitative Susceptibility Mapping Reconstruction.

Kan H, Arai N, Takizawa M, Kasai H, Kunitomo H, Hirose Y, Shibamoto Y

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine 18 巻 ( 4 ) 頁： 276 - 285 2019年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Magnetic Resonance in Medical Sciences

To mitigate the susceptibility inhomogeneity induced by radio-frequency transmit phase error through the whole brain in quantitative susceptibility mapping (QSM) using single-echo gradient echo sequence, we developed a novel single-step QSM reconstruction algorithm and compared it with a previous algorithm in five healthy volunteers. The proposed algorithm had effectively suppressed the susceptibility inhomogeneity through the whole brain and achieved acceptable quality, similar to that of the susceptibility map calculated from a multi-echo gradient echo sequence.

DOI： 10.2463/mrms.tn.2018-0066

Voxel-based quantitative susceptibility mapping in Parkinson's disease with mild cognitive impairment. 国際誌

Uchida Y, Kan H, Sakurai K, Arai N, Kato D, Kawashima S, Ueki Y, Matsukawa N

Movement disorders : official journal of the Movement Disorder Society 34 巻 ( 8 ) 頁： 1164 - 1173 2019年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Movement Disorders

Objective: Brain iron accumulation has been proposed as one of the pathomechanisms in Parkinson's disease (PD). This study aimed to examine the whole-brain pattern of iron accumulation associated with cognitive impairment in patients with PD using voxel-based quantitative susceptibility mapping analysis. Methods: We enrolled 24 patients with PD and mild cognitive impairment, 22 patients with PD and normal cognition, and 20 age-matched healthy controls in this cross-sectional study. All participants underwent global cognitive and physical assessments and brain MRI. Using a combined method of voxel-based morphometry and quantitative susceptibility mapping, we compared the voxel-wise magnetic susceptibility of the whole brain between the groups and analyzed its correlation with the cognitive and behavioral data. Results: The PD and mild cognitive impairment group had lower Montreal Cognitive Assessment (MoCA) score than the PD and normal cognition and healthy control groups. There were no gray matter volumetric differences between the groups. In contrast, the voxel-based quantitative susceptibility mapping analysis showed that the PD and mild cognitive impairment group had significantly higher quantitative susceptibility mapping values in the cuneus, precuneus, caudate head, fusiform gyrus, and orbitofrontal cortex than did the PD and normal cognition group. These quantitative susceptibility mapping values were negatively correlated with the MoCA scores in the PD patients (cuneus: r = −0.510, P <.001; caudate head: r = −0.458, P = 0.002). Conclusions: This study suggests that cognitive impairment in PD is associated with cerebral iron burden and highlights the potential of quantitative susceptibility mapping as an auxiliary biomarker for early evaluation of cognitive decline in patients with PD. © 2019 International Parkinson and Movement Disorder Society.

DOI： 10.1002/mds.27717

Geometric discrepancy of image-guided radiation therapy in patients with prostate cancer without implanted fiducial markers using a commercial pseudo-CT generation method.

Kan H, Eguchi Y, Tsuchiya T, Kondo T, Kitagawa Y, Mekata Y, Fukuma H, Yoshida R, Kasai H, Kunitomo H, Hirose Y, Shibamoto Y

Physics in medicine and biology 64 巻 ( 6 ) 頁： 06NT01 2019年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics in Medicine and Biology

MR-only simulations provide pseudo-CT images which are segmented into 5 kinds of tissues from DIXON-based images. However, it is difficult to register pseudo-CT images to cone-beam CT (CBCT) images collected for image-guided radiation therapy (IGRT), because of the lack of contrasts among tissues. We validated gaps of IGRT between pseudo-CT or planning CT and CBCT for patients without implanted markers. We also propose calcification-assisted registration for MR-only simulation. We conducted retrospective analyses to verify the registration accuracy in 15 patients who underwent volumetric modulated arc therapy (VMAT) for prostate cancer. They underwent planning CT and pseudo-CT. Pseudo-CT images after deformable image registration (DIR) to planning CT images were rendered automatic pelvic bone matching to CBCT images. Patient positions on the pseudo-CT images after DIR were shifted on the basis of tissues around the prostate. We compared registration gaps between the images of planning CT and pseudo-CT with DIR, assuming that the tissue-based matching between the planning CT and CBCT was the gold standard. To the pseudo-CT images with DIR, calcifications detected on planning CT were added. We validated IGRT accuracy for a calcification-assisted registration. The absolute registration errors of the pseudo-CT, in comparison with the planning CT, were 0.34 ± 0.50 (lateral), 1.3 ± 1.3 (longitudinal), and 1.1 ± 1.0 mm (vertical). The absolute registration errors of the pseudo-CT with calcification contouring, in comparison with the planning CT, were 0.41 ± 1.0 (lateral), 0.87 ± 0.92 (longitudinal), and 0.74 ± 0.64 mm (vertical). Reduced absolute registration errors were observed in the proposed approach in the longitudinal (P < 0.01) and vertical (P < 0.01) dimensions when using calcification-assisted registration. The tissue-based registration using the MR-only simulation was not sufficient for use in patients with prostate cancer without implanted markers. The calcification-assisted registration might help to improve IGRT accuracy using MRI alone.

DOI： 10.1088/1361-6560/ab02cc

Differentiation between malignant and benign musculoskeletal tumors using diffusion kurtosis imaging. 国際誌

Ogawa M, Kan H, Arai N, Murai T, Manabe Y, Sawada Y, Shibamoto Y

Skeletal radiology 48 巻 ( 2 ) 頁： 285 - 292 2019年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Skeletal Radiology

Objective: The purpose of this study was to evaluate differences in parameters of diffusion kurtosis imaging (DKI) and minimum apparent diffusion coefficient (ADC min ) between benign and malignant musculoskeletal tumors. Materials and methods: In this prospective study, 43 patients were scanned using a DKI protocol on a 3-T MR scanner. Eligibility criteria were: non-fatty, non-cystic soft tissue or osteolytic tumors; > 2 cm; location in the retroperitoneum, pelvis, leg, or neck; and no prior treatment. They were clinically or histologically diagnosed as benign (n = 27) or malignant (n = 16). In the DKI protocol, diffusion-weighted imaging was performed using four b values (0-2000 s/mm 2 ) and 21 diffusion directions. Mean kurtosis (MK) values were calculated on the MR console. A recently developed software application enabling reliable calculation was used for DKI analysis. Results: MK showed a strong correction with ADC min (Spearman’s rs = 0.95). Both MK and ADC min values differed between benign and malignant tumors (p < 0.01). For benign and malignant tumors, the mean MK values (± SD) were 0.49 ± 0.17 and 1.14 ± 0.30, respectively, and ADC min values were 1.54 ± 0.47 and 0.49 ± 0.17 × 10 −3 mm 2 /s, respectively. At cutoffs of MK = 0.81 and ADC min = 0.77 × 10 −3 mm 2 /s, the specificity and sensitivity for diagnosis of malignant tumors were 96.3 and 93.8% for MK and 96.3 and 93.8% for ADC min , respectively. The areas under the curve were 0.97 and 0.99 for MK and ADC min , respectively (p = 0.31). Conclusions: MK and ADC min showed high diagnostic accuracy and strong correlation, reflecting the accuracy of MK. However, no clear added value of DKI could be demonstrated in differentiating musculoskeletal tumors.

DOI： 10.1007/s00256-018-2946-0

Nigrostriatal Dopaminergic Dysfunction and Altered Functional Connectivity in REM Sleep Behavior Disorder With Mild Motor Impairment. 国際誌

Yamada G, Ueki Y, Oishi N, Oguri T, Fukui A, Nakayama M, Sano Y, Kandori A, Kan H, Arai N, Sakurai K, Wada I, Matsukawa N

Frontiers in neurology 10 巻 ( JUL ) 頁： 802 - 802 2019年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Frontiers in Neurology

Rapid eye movement sleep behavior disorder is parasomnia characterized by symptoms of dream enactment and loss of muscle atonia during rapid eye movement sleep. Mild motor impairment is present in some patients with rapid eye movement sleep behavior disorder and presumed to be a risk factor for conversion to synucleinopathies. The purpose of this study is to identify patients with mild motor impairment by evaluating finger tapping and to investigate its pathophysiology. Twenty-three patients with rapid eye movement sleep behavior disorder and 20 healthy control subjects were recruited in the present study. We accurately evaluated finger tapping including amplitude, peak open, and close speed with a magnetic sensing device and identified patients with mild motor impairment. Moreover, we performed 123I-2b-carbomethoxy-3b-(4-iodophenyl) nortropane SPECT and resting state functional MRI. 123I-2b-carbomethoxy-3b-(4-iodophenyl) nortropane uptake for each bilateral caudate, anterior putamen, and posterior putamen was calculated and the resting state functional connectivity of sensorimotor network was analyzed. Using finger tapping parameters, we identified eight patients with mild motor impairment. In patients with mild motor impairment, all finger tapping parameters were significantly impaired when compared to patients with normal motor function, while they exhibited no significant differences in Unified Parkinsons Disease Rating Scale part III score. 123I-2b-carbomethoxy-3b-(4-iodophenyl) nortropane uptake in the right posterior putamen, bilateral anterior putamen, and caudate was significantly lower when compared to healthy controls or patients with rapid eye movement sleep behavior disorder with normal motor function. These patients also exhibited decreased cortico-striatal functional connectivity and increased cortico-cerebellar functional connectivity when compared to healthy controls or patients with normal motor function. Our results show that mild motor impairment in rapid eyemovement sleep behavior disorder evaluated by finger tapping task presented mild nigrostriatal dopaminergic dysfunction as well as alterations in resting state sensorimotor network. Although longitudinal follow up is necessary, such patients may have higher risk of short-term conversion to synucleinopathies.

DOI： 10.3389/fneur.2019.00802

Background field removal technique based on non-regularized variable kernels sophisticated harmonic artifact reduction for phase data for quantitative susceptibility mapping.

Kan H, Arai N, Takizawa M, Omori K, Kasai H, Kunitomo H, Hirose Y, Shibamoto Y

Magnetic resonance imaging 52 巻頁： 94 - 101 2018年10月

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