Updated on 2024/02/22

写真a

 
KAN Hirohito
 
Organization
Graduate School of Medicine Assistant Professor
Graduate School
Graduate School of Medicine
Undergraduate School
School of Health Sciences
Title
Assistant Professor
Contact information
メールアドレス

Degree 1

  1. 博士(保健学) ( 2015.3   金沢大学 ) 

Research History 3

  1. Nagoya University   Graduate School of Medicine   Assistant Professor

    2020.4

  2. Nagoya University   Graduate School of Medicine Department of Radiological and Medical Laboratory Sciences Radiological Sciences   Assistant Professor

    2019.9 - 2020.3

  3. Nagoya City University Hospital   Department of Radiology

    2011.4 - 2019.8

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    Country:Japan

Professional Memberships 3

  1. International Society for Magnetic Resonance in Medicine

  2. 日本放射線技術学会

  3. 日本磁気共鳴医学会

 

Papers 54

  1. Longitudinal Changes in Iron and Myelination Within Ischemic Lesions Associate With Neurological Outcomes: A Pilot Study.

    Uchida Y, Kan H, Kano Y, Onda K, Sakurai K, Takada K, Ueki Y, Matsukawa N, Hillis AE, Oishi K

    Stroke     2024.1

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

    DOI: 10.1161/STROKEAHA.123.044606

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  2. Brain Abnormalities in Becker Muscular Dystrophy: Evaluation by Voxel-Based DTI and Morphometric Analysis.

    Maki H, Mori-Yoshimura M, Matsuda H, Hashimoto Y, Ota M, Kimura Y, Shigemoto Y, Ishihara N, Kan H, Chiba E, Arizono E, Yoshida S, Takahashi Y, Sato N

    AJNR. American journal of neuroradiology     2023.11

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

    DOI: 10.3174/ajnr.A8041

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  3. Relationship between brain iron dynamics and blood-brain barrier function during childhood: a quantitative magnetic resonance imaging study.

    Uchida Y, Kan H, Furukawa G, Onda K, Sakurai K, Takada K, Matsukawa N, Oishi K

    Fluids and barriers of the CNS   Vol. 20 ( 1 ) page: 60   2023.8

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

    DOI: 10.1186/s12987-023-00464-x

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  4. Three-compartment spectral diffusion analysis for breast cancer magnetic resonance imaging.

    Ogawa M, Kan H, Urano M, Kawai T, Nakajima H, Murai K, Miyaji H, Toyama T, Hiwatashi A

    Magnetic resonance imaging     2023.5

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

    DOI: 10.1016/j.mri.2023.04.006

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  5. Voxel-Based and Surface-Based Morphometry Analysis in Patients with Pathologically Confirmed Argyrophilic Grain Disease and Alzheimer's Disease.

    Sakurai K, Kaneda D, Morimoto S, Uchida Y, Inui S, Kimura Y, Kan H, Kato T, Ito K, Hashizume Y

    Journal of Alzheimer's disease : JAD     2023.3

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    DOI: 10.3233/JAD-230068

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  6. Contributions of blood-brain barrier imaging to neurovascular unit pathophysiology of Alzheimer's disease and related dementias.

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

    Frontiers in aging neuroscience   Vol. 15   page: 1111448   2023

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Frontiers in Aging Neuroscience  

    The blood–brain barrier (BBB) plays important roles in the maintenance of brain homeostasis. Its main role includes three kinds of functions: (1) to protect the central nervous system from blood-borne toxins and pathogens; (2) to regulate the exchange of substances between the brain parenchyma and capillaries; and (3) to clear metabolic waste and other neurotoxic compounds from the central nervous system into meningeal lymphatics and systemic circulation. Physiologically, the BBB belongs to the glymphatic system and the intramural periarterial drainage pathway, both of which are involved in clearing interstitial solutes such as β-amyloid proteins. Thus, the BBB is believed to contribute to preventing the onset and progression for Alzheimer’s disease. Measurements of BBB function are essential toward a better understanding of Alzheimer’s pathophysiology to establish novel imaging biomarkers and open new avenues of interventions for Alzheimer’s disease and related dementias. The visualization techniques for capillary, cerebrospinal, and interstitial fluid dynamics around the neurovascular unit in living human brains have been enthusiastically developed. The purpose of this review is to summarize recent BBB imaging developments using advanced magnetic resonance imaging technologies in relation to Alzheimer’s disease and related dementias. First, we give an overview of the relationship between Alzheimer’s pathophysiology and BBB dysfunction. Second, we provide a brief description about the principles of non-contrast agent-based and contrast agent-based BBB imaging methodologies. Third, we summarize previous studies that have reported the findings of each BBB imaging method in individuals with the Alzheimer’s disease continuum. Fourth, we introduce a wide range of Alzheimer’s pathophysiology in relation to BBB imaging technologies to advance our understanding of the fluid dynamics around the BBB in both clinical and preclinical settings. Finally, we discuss the challenges of BBB imaging techniques and suggest future directions toward clinically useful imaging biomarkers for Alzheimer’s disease and related dementias.

    DOI: 10.3389/fnagi.2023.1111448

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  7. Assessing white matter microstructural changes in idiopathic normal pressure hydrocephalus using voxel-based R2* relaxometry analysis.

    Kano Y, Uchida Y, Kan H, Sakurai K, Kobayashi S, Seko K, Mizutani K, Usami T, Takada K, Matsukawa N

    Frontiers in neurology   Vol. 14   page: 1251230   2023

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    Background: R2* relaxometry and quantitative susceptibility mapping can be combined to distinguish between microstructural changes and iron deposition in white matter. Here, we aimed to explore microstructural changes in the white matter associated with clinical presentations such as cognitive impairment in patients with idiopathic normal-pressure hydrocephalus (iNPH) using R2* relaxometry analysis in combination with quantitative susceptibility mapping. Methods: We evaluated 16 patients clinically diagnosed with possible or probable iNPH and 18 matched healthy controls (HC) who were chosen based on similarity in age and sex. R2* and quantitative susceptibility mapping were compared using voxel-wise and atlas-based one-way analysis of covariance (ANCOVA). Finally, partial correlation analyses were performed to assess the relationship between R2* and clinical presentations. Results: R2* was lower in some white matter regions, including the bilateral superior longitudinal fascicle and sagittal stratum, in the iNPH group compared to the HC group. The voxel-based quantitative susceptibility mapping results did not differ between the groups. The atlas-based group comparisons yielded negative mean susceptibility values in almost all brain regions, indicating no clear paramagnetic iron deposition in the white matter of any subject. R2* and cognitive performance scores between the left superior longitudinal fasciculus (SLF) and right sagittal stratum (SS) were positively correlated. In addition to that, R2* and gait disturbance scores between left SS were negatively correlated. Conclusion: Our analysis highlights the microstructural changes without iron deposition in the SLF and SS, and their association with cognitive impairment and gait disturbance in patients with iNPH.

    DOI: 10.3389/fneur.2023.1251230

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  8. Noncontrast time-resolved pulmonary magnetic resonance angiography with consecutive beam saturation pulse and variable flip angles using three-dimensional fast spin echo: A preliminary study. International journal

    Hirohito Kan, Kyosuke Mizuno, Masahiro Takizawa, Masashi Shimohira, Tatsuya Kawai, Toshitaka Aoki, Satoshi Tsubokura, Harumasa Kasai

    Magnetic resonance imaging   Vol. 94   page: 80 - 88   2022.12

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    To develop and validate a novel noncontrast time-resolved magnetic resonance angiography (NC TR-MRA) using consecutive beam pulses with variable flip angles for visualizing hemodynamics in the pulmonary artery, we performed phantom and volunteer studies and applied the novel NC TR-MRA to a 51-year-old woman with pulmonary arteriovenous malformation (PAVM).The novel NC TR-MRA sequence utilized consecutive multiple-beam saturation pulses with variable flip angles considering venous blood T1 relaxation to alter the visualized blood signal length. The flowing blood signal length is suppressed according to the number of beam saturation pulses. NC TR-MRA in each flow phase was assessed by subtracting the images with and without beam saturation pulses. In the flow phantom study, three flow velocities were used to simulate physiological pulmonary arterial blood flow. Signal profiles along the flow direction were evaluated in each flow phase. In the volunteer study, five healthy volunteers were recruited, and NC TR-MRA was applied to evaluate relationships between the flow-saturated time and signal enhancement rates. Four regions of interest (ROIs) were determined on the proximal and distal portions of the right basal artery. A patient with PAVM was included to validate whether a PAVM lesion could be visualized using NC TR-MRA. The visualized flow signal lengths extended proportionally with the number of beam saturation pulses in the steady-flow phantom at all velocities. In the volunteer study, NC TR-MRA images showed signal enhancement from the proximal to distal portions of the right basal artery with increase in the flow-saturated time. Signal enhancement rates in all ROIs were significantly positively correlated with the flow-saturated time (p < 0.001 in all ROIs). Further, the lesion and its hemodynamics could be explicitly visualized in the patient with PAVM. Hence, NC TR-MRA using beam saturation pulse can visualize the hemodynamics of the pulmonary artery and may be useful for diagnosing and following patients with PAVM.

    DOI: 10.1016/j.mri.2022.09.001

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  9. Memantine for the patients with mild cognitive impairment in Parkinson’s disease: a pharmacological fMRI study

    Kawashima S., Shimizu Y., Horiba M., Ueki Y., Akanabe R., Kan H., Kasai H., Kunitomo H., Tanaka S., Toyota T., Kawashima S., Mizuno M., Okita K., Matsukawa N.

    BMC Neurology   Vol. 22 ( 1 )   2022.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:BMC Neurology  

    Background: Mild cognitive impairment in Parkinson’s disease (PD-MCI) is associated with an increased risk of cognitive decline. PD-MCI is characterized by impairments in executive function and visuospatial recognition. The visuospatial n-back test is useful for assessing both domains. The 0-back test reflects visuospatial recognition, while the 1-back and 2-back tests reflect working memory. Cholinesterase inhibitors are effective in the treatment of PD-MCI and dementia in PD (PDD). Although some studies have reported the efficacy of memantine for PDD, the therapeutic efficacy of memantine in patients with PD-MCI remains uncertain. Methods: This study aimed to investigate the effects of memantine on brain function in patients with PD-MCI, using a randomized double-blinded crossover protocol and functional MRI (fMRI). Ten patients who completed 16 weeks of follow-up were included. They were randomly assigned to either the memantine or placebo. Patients in the memantine group received 5 mg/day of memantine in the first week. The memantine dose was increased by 5 mg/day per week, until a final dose of 20 mg/day. Patients in the placebo group received the placebo following the same regimen as memantine. After the intervention, they underwent a 4 weeks washout period. Following the crossover protocol, a second intervention was conducted after the washout period. In each intervention, fMRI and neuropsychological tests were performed at the maximum dose period. Comparing the memantine and placebo groups, we investigated difference in the brain regions using the visuospatial n-back test. Results: There were no significant regions enhanced by memantine comparing with placebo at any load of n-back tests. In contrast, exploring regions reduced by memantine, we found significant reduction of activations within right lingual gyrus and left superior frontal gyrus in comparison between 2-back and 0-back test. A number of correct answers of the 2-back test and time to complete Trail Making Test-A were worse during memantine intervention. Conclusions: Memantine did not improve visuospatial working memory of the patients with PD-MCI. Treatment for PD should be planned carefully considering the impact on cognitive function. Further study is needed to establish new therapeutic strategy. Trial registration: UMIN000046104. Retrospectively registered. First registration date: 28 Sept 2017.

    DOI: 10.1186/s12883-022-02699-x

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  10. APOE ɛ4 dose associates with increased brain iron and β-amyloid via blood-brain barrier dysfunction. International journal

    Yuto Uchida, Hirohito Kan, Keita Sakurai, Yoshihiko Horimoto, Emi Hayashi, Akihiko Iida, Nobuyuki Okamura, Kenichi Oishi, Noriyuki Matsukawa

    Journal of neurology, neurosurgery, and psychiatry   Vol. 93 ( 7 ) page: 772 - 778   2022.4

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    OBJECTIVE: To examine the effect of apolipoprotein E (APOE) ɛ4 dose on blood-brain barrier (BBB) clearance function, evaluated using an advanced MRI technique and analyse its correlation with brain iron and β-amyloid accumulation in the early stages of the Alzheimer's continuum. METHODS: In this single-centre observational prospective cohort study, 24 APOE ɛ4 non-carriers, 22 heterozygotes and 20 homozygotes in the early stages of the Alzheimer's continuum were scanned with diffusion-prepared arterial spin labelling, which estimates the water exchange rate across the BBB (kw). Participants also underwent quantitative susceptibility mapping, [11C]Pittsburgh compound B-positron emission tomography and neuropsychological testing. Using an atlas-based approach, we compared the regional kw of the whole brain among the groups and analysed its correlation with the neuroradiological and neuropsychological findings. RESULTS: The BBB kw values in the neocortices differed significantly among the groups (APOE ɛ4 non-carriers>heterozygotes>homozygotes). These values correlated with brain iron levels (frontal lobe: r=-0.476, 95% CI=-0.644 to -0.264, p=0.011; medial temporal lobe: r=-0.455, 95% CI=-0.628 to -0.239, p=0.017), β-amyloid loads (frontal lobe: r=-0.504, 95% CI=-0.731 to -0.176, p=0.015; medial temporal lobe: r=-0.452, 95% CI=-0.699 to -0.110, p=0.036) and neuropsychological scores, after adjusting for age, sex and APOE ɛ4 dose. INTERPRETATION: Our results suggest that an increased APOE ɛ4 dose is associated with decreased effective brain-waste clearance, such as iron and β-amyloid, through the BBB.

    DOI: 10.1136/jnnp-2021-328519

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  11. Delineation of prostatic calcification using quantitative susceptibility mapping: Spatial accuracy for magnetic resonance-only radiotherapy planning. International journal

    Hirohito Kan, Takahiro Tsuchiya, Masato Yamada, Hiroshi Kunitomo, Harumasa Kasai, Yuta Shibamoto

    Journal of applied clinical medical physics   Vol. 23 ( 2 ) page: e13469   2022.2

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    To investigate the spatial accuracy of delineating prostatic calcifications by quantitative susceptibility mapping (QSM) in comparison with computed tomography (CT), we conducted phantom and human studies. Five differently-sized spherical hydroxyapatites mimicking prostatic calcification (pseudo-calcification) were arranged in the order of their sizes at the center of a plastic container filled with gelatin. This calcification phantom underwent magnetic resonance (MR) imaging, including the multiple spoiled gradient-echo sequences (SPGR) for the QSM and CT as a reference. The volume of each pseudo-calcification and center-to-center distance between the pseudo-calcifications delineated by QSM and CT were measured. In the human study, eight patients with prostate cancer who underwent radiation therapy and had some prostatic calcifications were included. The patients underwent CT and SPGR and modified DIXON sequence for MR-only simulation. The hybrid QSM processing combined with the complex signals in the SPGR and water and fat fraction maps estimated from the modified DIXON sequence were used to reconstruct the pelvic susceptibility map in humans. The threshold of CT numbers was set at 130 HU, while the QSM images were manually segmented in the calcification phantom and human studies. In the phantom study, there was an excellent agreement in the pseudo-calcification volumes between QSM and CT (y = 1.02x - 7.38, R2  = 0.99). The signal profiles had similar trends in CT and QSM. The center-to-center distances between the pseudo-calcifications in the phantom were also identical in QSM and CT. The calcification volumes were almost identical between the QSM and CT in the human study (y = 0.95x - 9.32, R2  = 1.00). QSM can offer geometric and volumetric accuracies to delineate prostatic calcifications, similar to CT. The prostatic calcification delineated by QSM may facilitate image-guided radiotherapy in the MR-only simulation workflow.

    DOI: 10.1002/acm2.13469

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

    Haruto Shibata, Yuto Uchida, Shohei Inui, Hirohito Kan, Keita Sakurai, Naoya Oishi, Yoshino Ueki, Kenichi Oishi, Noriyuki Matsukawa

    Parkinsonism & Related Disorders   Vol. 94   page: 104 - 110   2022.1

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.parkreldis.2021.12.004

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

    Yuto Uchida, Hirohito Kan, Hiroyasu Inoue, Masahiro Oomura, Haruto Shibata, Yuya Kano, Tomoyuki Kuno, Toshihiko Usami, Koji Takada, Kentaro Yamada, Kohsuke Kudo, Noriyuki Matsukawa

    Frontiers in Neurology   Vol. 13   page: 752450   2022

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

    <sec><title>Background</title>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.

    </sec><sec><title>Materials and Methods</title>This prospective imaging study included 21 patients with large anterior circulation vessel occlusion who were admitted &amp;lt;24 h after stroke onset and 21 age-matched healthy controls. We identified the ischemic penumbra as the region with a Tmax of &amp;gt;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.

    </sec><sec><title>Results</title>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 &amp;gt;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 (<italic>r</italic> = 0.636, 95% CI: 0.059 to 0.895, <italic>P</italic> = 0.035) and inversely correlated with the 30-day change in the National Institutes of Health Stroke Scale scores (<italic>r</italic> = −0.624, 95% CI: −0.891 to −0.039, <italic>P</italic> = 0.041).

    </sec><sec><title>Conclusion</title>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.

    </sec>

    DOI: 10.3389/fneur.2022.752450

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

    Hirohito Kan, Yuto Uchida, Yoshino Ueki, Nobuyuki Arai, Satoshi Tsubokura, Hiroshi Kunitomo, Harumasa Kasai, Kiminori Aoyama, Noriyuki Matsukawa, Yuta Shibamoto

    NeuroImage. Clinical   Vol. 33   page: 102938 - 102938   2022

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    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

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

    Yuto Uchida, Hirohito Kan, Keita Sakurai, Kenichi Oishi, Noriyuki Matsukawa

    Frontiers in Neuroscience   Vol. 16   page: 938092   2022

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    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

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  16. 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   Vol. 16   page: 870733   2022

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    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

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  17. 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   Vol. 16 ( 4 ) page: e0249433   2021

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    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

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  18. Reply

    Arai N

    American Journal of Neuroradiology   Vol. 41 ( 4 ) page: E21 - E21   2020.4

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

    DOI: 10.3174/AJNR.A6473

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

    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   Vol. 53 ( 4 ) page: 1200 - 1207   2021.4

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    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.

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  20. 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.

    Masaki Ogawa, Motoo Nakagawa, Nobuyuki Arai, Hirohito Kan, Shota Ohba, Shunsuke Shibata, Hiroyuki Maki, Yuta Shibamoto

    Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine   Vol. 19 ( 4 ) page: 382 - 388   2020.12

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    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.

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  21. Decreasing iron susceptibility with temperature in quantitative susceptibility mapping: A phantom study. International journal

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

    Magnetic resonance imaging   Vol. 73   page: 55 - 61   2020.11

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    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.

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  22. Iron leakage owing to blood-brain barrier disruption in small vessel disease CADASIL. International journal

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

    Neurology   Vol. 95 ( 9 ) page: e1188 - e1198   2020.9

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    OBJECTIVE: To 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). METHODS: We 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. RESULTS: Among 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). CONCLUSIONS: This 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.

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  23. Magnetic Susceptibility Associates with Dopaminergic Deficits and Cognition in Parkinson's Disease. International journal

    Yuto Uchida, Hirohito Kan, Keita Sakurai, Shohei Inui, Susumu Kobayashi, Yoshihiro Akagawa, Kazuyoshi Shibuya, Yoshino Ueki, Noriyuki Matsukawa

    Movement disorders : official journal of the Movement Disorder Society   Vol. 35 ( 8 ) page: 1396 - 1405   2020.8

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    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 123 I-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.

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

    Kan, Hirohito, Uchida, Yuto, Arai, Nobuyuki, Ueki, Yoshino, Aoki, Toshitaka, Kasai, Harumasa, Kunitomo, Hiroshi, Hirose, Yasujiro, Matsukawa, Noriyuki, Shibamoto, Yuta

    NMR IN BIOMEDICINE   Vol. 33 ( 5 ) page: e4272   2020.5

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    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 T-1-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.

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  25. Visualization of nigrosome 1 from the viewpoint of anatomic structure

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

    American Journal of Neuroradiology   Vol. 41 ( 1 ) page: 86 - 91   2020.1

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    © 2020 American Society of Neuroradiology. All rights reserved. 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.

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

    Hirohito Kan, Nobuyuki Arai, Masahiro Takizawa, Harumasa Kasai, Hiroshi Kunitomo, Yasujiro Hirose, Yuta Shibamoto

    Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine   Vol. 18 ( 4 ) page: 276 - 285   2019.10

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    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.

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  27. Voxel-based quantitative susceptibility mapping in Parkinson's disease with mild cognitive impairment. International journal

    Yuto Uchida, Hirohito Kan, Keita Sakurai, Nobuyuki Arai, Daisuke Kato, Shoji Kawashima, Yoshino Ueki, Noriyuki Matsukawa

    Movement disorders : official journal of the Movement Disorder Society   Vol. 34 ( 8 ) page: 1164 - 1173   2019.8

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    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.

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  28. 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   Vol. 64 ( 6 ) page: 06NT01   2019.3

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  29. Differentiation between malignant and benign musculoskeletal tumors using diffusion kurtosis imaging. International journal

    Masaki Ogawa, Hirohito Kan, Nobuyuki Arai, Taro Murai, Yoshihiko Manabe, Yusuke Sawada, Yuta Shibamoto

    Skeletal radiology   Vol. 48 ( 2 ) page: 285 - 292   2019.2

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    OBJECTIVE: The purpose of this study was to evaluate differences in parameters of diffusion kurtosis imaging (DKI) and minimum apparent diffusion coefficient (ADCmin) 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/mm2) 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 ADCmin (Spearman's rs = 0.95). Both MK and ADCmin 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 ADCmin values were 1.54 ± 0.47 and 0.49 ± 0.17 × 10-3 mm2/s, respectively. At cutoffs of MK = 0.81 and ADCmin = 0.77 × 10-3 mm2/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 ADCmin, respectively. The areas under the curve were 0.97 and 0.99 for MK and ADCmin, respectively (p = 0.31). CONCLUSIONS: MK and ADCmin 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.

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  30. Nigrostriatal Dopaminergic Dysfunction and Altered Functional Connectivity in REM Sleep Behavior Disorder With Mild Motor Impairment. International journal

    Gohei Yamada, Yoshino Ueki, Naoya Oishi, Takuya Oguri, Ayako Fukui, Meiho Nakayama, Yuko Sano, Akihiko Kandori, Hirohito Kan, Nobuyuki Arai, Keita Sakurai, Ikuo Wada, Noriyuki Matsukawa

    Frontiers in neurology   Vol. 10 ( JUL ) page: 802 - 802   2019

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    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-2β-carbomethoxy-3β-(4-iodophenyl) nortropane SPECT and resting state functional MRI. 123I-2β-carbomethoxy-3β-(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 Parkinson's Disease Rating Scale part III score. 123I-2β-carbomethoxy-3β-(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 eye movement 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.

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  31. 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   Vol. 52   page: 94 - 101   2018.10

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  32. Hybrid quantitative MRI using chemical shift displacement and recovery-based simultaneous water and lipid imaging: A preliminary study.

    Ohno N, Miyati T, Suzuki S, Kan H, Aoki T, Nakamura Y, Hiramatsu Y, Kobayashi S, Gabata T

    Magnetic resonance imaging   Vol. 50   page: 61 - 67   2018.7

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  33. Utility of the variable flip angle 3D fast-spin echo (isoFSE) sequence on 3T MR for diagnosing vertebrobasilar artery dissection.

    Ogawa M, Omata S, Kan H, Arai N, Asai M, Urano M, Shibamoto Y

    Radiological physics and technology   Vol. 11 ( 2 ) page: 228 - 234   2018.6

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  34. Novel practical SNR determination method for MRI using double echo with longest second echo time (DELSET).

    Ohno N, Miyati T, Niwa Y, Kan H, Ishida S, Kasai H, Shibamoto Y, Gabata T

    The British journal of radiology   Vol. 91 ( 1086 ) page: 20170652   2018.6

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  35. Time-resolved magnetic resonance angiography as a follow-up method for visceral artery aneurysm treated with coil-embolisation.

    Kawai T, Shimohira M, Suzuki K, Ohta K, Kurosaka K, Hashizume T, Nishikawa H, Muto M, Arai N, Kan H, Shibamoto Y

    Polish journal of radiology   Vol. 83   page: e137 - e142   2018

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  36. Neural Basis of Self-Reflection on Self-Face Image in Patients with Social Anxiety Disorder

    KAWAGUCHI Akiko, MORITA Tomoyo, OKAMOTO Yasumasa, NAKAAKI Shutaro, KAWAGUCHI Takatsune, KAN Hirohito, YAMADA Takahiro, AKECHI Tatsuo, SADATO Norihiro

      Vol. 10 ( 1 ) page: 29-44   2018

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  37. Quantitative susceptibility mapping using principles of echo shifting with a train of observations sequence on 1.5T MRI.

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

    Magnetic resonance imaging   Vol. 42   page: 37 - 42   2017.10

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  38. Water and lipid diffusion MRI using chemical shift displacement-based separation of lipid tissue (SPLIT).

    Ohno N, Kan H, Miyati T, Aoki T, Ishida S, Gabata T

    Magnetic resonance imaging   Vol. 39   page: 144 - 148   2017.6

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  39. Background field removal technique using regularization enabled sophisticated harmonic artifact reduction for phase data with varying kernel sizes.

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

    Magnetic resonance imaging   Vol. 34 ( 7 ) page: 1026 - 33   2016.9

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  40. Insular Volume Reduction in Patients with Social Anxiety Disorder.

    Kawaguchi A, Nemoto K, Nakaaki S, Kawaguchi T, Kan H, Arai N, Shiraishi N, Hashimoto N, Akechi T

    Frontiers in psychiatry   Vol. 7 ( JAN ) page: 3   2016

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  41. Hemodynamic Independent Analysis of &Delta;ADC in Brain Using Diffusion and Perfusion MRI

    KITANAKA Akihiro, MIYATI Tosiaki, OHNO Naoki, KAN Hirohito, MASE Mitsuhito, KOBAYASHI Satoshi, GABATA Toshifumi

      Vol. 33 ( 1 ) page: vii-xi   2016

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  42. Shortened breath-hold contrast-enhanced MRI of the liver using a new parallel imaging technique, CAIPIRINHA (controlled aliasing in parallel imaging results in higher acceleration): a comparison with conventional GRAPPA technique.

    Ogawa M, Kawai T, Kan H, Kobayashi S, Akagawa Y, Suzuki K, Nojiri S, Ozawa Y, Shibamoto Y

    Abdominal imaging   Vol. 40 ( 8 ) page: 3091 - 8   2015.10

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  43. Dynamic state of water molecular displacement of the brain during the cardiac cycle in idiopathic normal pressure hydrocephalus.

    Kan H, Miyati T, Mase M, Osawa T, Ohno N, Kasai H, Arai N, Kawano M, Shibamoto Y

    Computerized medical imaging and graphics : the official journal of the Computerized Medical Imaging Society   Vol. 40   page: 88 - 93   2015.3

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  44. Transfer characteristics of arterial pulsatile force in regional intracranial tissue using dynamic diffusion MRI: a phantom study.

    Kan H, Miyati T, Kasai H, Arai N, Ohno N, Mase M, Shibamoto Y

    Magnetic resonance imaging   Vol. 32 ( 10 ) page: 1284 - 9   2014.12

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  45. Feasibility of time-resolved MR angiography for detecting recanalization of pulmonary arteriovenous malformations treated with embolization with platinum coils.

    Kawai T, Shimohira M, Kan H, Hashizume T, Ohta K, Kurosaka K, Muto M, Suzuki K, Shibamoto Y

    Journal of vascular and interventional radiology : JVIR   Vol. 25 ( 9 ) page: 1339 - 47   2014.9

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  46. A method for assessing metabolic information on liver and bone marrow by use of double gradient-echo with spectral fat suppression.

    Kasai H, Miyati T, Kawai T, Kan H, Kawano M, Shibamoto Y

    Radiological physics and technology   Vol. 7 ( 2 ) page: 211 - 6   2014.7

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    Publishing type:Research paper (scientific journal)   Publisher:Radiological Physics and Technology  

    DOI: 10.1007/s12194-013-0254-x

    Scopus

    PubMed

  47. Delta-ADC (Apparent diffusion coefficient) analysis in patients with idiopathic normal pressure hydrocephalus

    Osawa T.

    Acta Neurochirurgica, Supplementum   Vol. 114   page: 197 - 200   2012

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    Publishing type:Research paper (scientific journal)   Publisher:Acta Neurochirurgica, Supplementum  

    DOI: 10.1007/978-3-7091-0956-4_38

    Scopus

  48. Hemodynamic-independent Analysis of Water Molecules Fluctuation in Brain Using MRI

    KAN Hirohito, YORIMITSU Risa, MIYATI Tosiaki, MASE Mitsuhito, KASAI Harumasa, OHNO Naoki, KAWANO Makoto, HARA Masaki, SHIBAMOTO Yuta, KITANAKA Akihiro

      Vol. 29 ( 1 ) page: 23-27   2012

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

    DOI: 10.11318/mii.29.23

  49. Q-space Diffusion MRI in Vertebral Bone Marrow

    YORIMITSU Risa, KAWANO Makoto, MIYATI Tosiaki, KAN Hirohito, OHNO Naoki, HARA Masaki, SHIBAMOTO Yuta, KASAI Harumasa, ARAI Nobuyuki, MIZUKAMI Yuji

      Vol. 29 ( 1 ) page: 20-22   2012

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

    DOI: 10.11318/mii.29.20

  50. Idiopathic normal-pressure hydrocephalus: temporal changes in ADC during cardiac cycle.

    Ohno N, Miyati T, Mase M, Osawa T, Kan H, Kasai H, Hara M, Shibamoto Y, Hayashi N, Gabata T, Matsui O

    Radiology   Vol. 261 ( 2 ) page: 560 - 5   2011.11

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    Publishing type:Research paper (scientific journal)   Publisher:Radiology  

    DOI: 10.1148/radiol.11101860

    Web of Science

    Scopus

    PubMed

  51. [Appropriate cardiac phase for measurement of ADC of the brain using ECG-triggered diffusion MRI].

    Kan H, Miyati T, Mase M, Kasai H, Hara M, Shibamoto Y, Kawano M, Ohno N, Kitanaka A, Yorimitsu R, Minami T

    Nihon Hoshasen Gijutsu Gakkai zasshi   Vol. 67 ( 6 ) page: 661 - 5   2011

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    PubMed

  52. [Analyses of restricted diffusion of water molecules using trabecular bone phantom].

    Minami T, Miyati T, Ueda Y, Kan H, Kitanaka A, Kasai H, Arai N, Hara M, Shibamoto Y, Yokoti S

    Nihon Hoshasen Gijutsu Gakkai zasshi   Vol. 67 ( 6 ) page: 634 - 9   2011

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    PubMed

  53. Re-examination of Signals and Contrasts of Fat with Short Echo Space using Fast Spin Echo Sequence

    KAN Hirohito, MIYATI Tosiaki, SAKURAI Ryosuke, KASAI Harumasa, KAWANO Makoto, YORIMITSU Risa, KITANAKA Akihiro, MIHIRA Sayumi

    Medical Imaging and Information Sciences   Vol. 28 ( 3 ) page: 79-82   2011

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

    Fast spin echo(FSE)sequence has been widely recognized that the contrast of T<sub>2</sub> weighted image was affected by multi-refocusing pulses. The contrasts have never been investigated in case of echo space(ES)below 20msec although magnetic resonance imaging(MRI)developed such that the ES of multi-refocusing pulses could set at 5msec. To evaluate the contrasts of fat with short ES, we determined the signal intensities of the brain tissues and bottle phantom which consists of lard, water and bean oil. The signal intensities of all regions increased with decreasing echo spaces, due to the decoupling of J-coupling, excepting water signal intensity. In addition, the contrasts between the white matter and each region decreased with decreasing ES until 10ms and, however, did not change with decreasing ES over 10ms. The contrast between white and gray matter is also discussed. It is concluded that the contrast does not change in case of the echo space below 10ms.

    DOI: 10.11318/mii.28.79

  54. Regional &Delta;ADC analysis of the brain during the cardiac cycle

    OHNO Naoki, UEDA Yu, MIYATI Tosiaki, MASE Mitsuhito, KASAI Harumasa, KAN Hirohito, ASAHI Miyuki, KAWANO Makoto, HARA Masaki, SHIBAMOTO Yuta

    Medical Imaging and Information Sciences   Vol. 26 ( 1 ) page: 17-20   2009

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

    We evaluated regional apparent diffusion coefficient (ADC) change of the brain during the cardiac cycle (&Delta;ADC) . On a 1.5-T MRI, ECG-triggered single-shot diffusion echo planar imaging was used with sensitivity encoding, half scan and rectangular FOV techniques to minimize the bulk motion such as brain pulsation, i.e., data-sampling window of 3ms. &Delta;ADC image was calculated from maximum minus minimum ADC value of all cardiac phase images on a pixel-by-pixel basis. We determined &Delta;ADC in regions of parietal, frontal, temporal and occipital white matters (WM) in twelve healthy volunteers. Moreover, we assessed influences of scan parameters on &Delta;ADC. &Delta;ADC was affected by b-values, but unaffected by voxel size. There was no significant correlation between &Delta;ADC and ADC. The &Delta;ADC values in parietal WM at centrum semiovale level were significantly higher than those in temporal WM at basal ganglia level, although there was no significant difference in ADC values between among WM regions. &Delta;ADC analysis using appropriate scan parameter makes it possible to noninvasively obtain new and more detailed information on the regional brain condition.

    DOI: 10.11318/mii.26.17

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Books 2

  1. 認知症専門医のための臨床神経病理学

    入江修司 編( Role: Contributor)

    株式会社ワールドプランニング  2019.5 

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    Language:Japanese Book type:Scholarly book

  2. 新 腹部画像診断の勘ドコロ

    兼松雅之 編( Role: Contributor)

    2014.10 

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    Language:Japanese Book type:Scholarly book

MISC 22

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

    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   Vol. 34 ( 8 ) page: 1164-1173   2019.8

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    Language:English  

    DOI: 10.1002/mds.27717

    PubMed

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

    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   Vol. 64 ( 6 ) page: 06NT01   2019.3

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    Language:English  

    DOI: 10.1088/1361-6560/ab02cc

    PubMed

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

    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     2019.2

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    Language:English  

    DOI: 10.2463/mrms.tn.2018-0066

    PubMed

  4. Differentiation between malignant and benign musculoskeletal tumors using diffusion kurtosis imaging Reviewed

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

    Skeletal radiology   Vol. 48 ( 2 ) page: 285-292   2019.2

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    Language:English  

    DOI: 10.1007/s00256-018-2946-0

    PubMed

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

    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   Vol. 10   page: 802   2019

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    Language:English  

    DOI: 10.3389/fneur.2019.00802

    PubMed

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

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

    Magnetic resonance imaging   Vol. 52   page: 94-101   2018.10

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    Language:English  

    DOI: 10.1016/j.mri.2018.06.006

    PubMed

  7. Hybrid quantitative MRI using chemical shift displacement and recovery-based simultaneous water and lipid imaging: A preliminary study. Reviewed

    Ohno N, Miyati T, Suzuki S, Kan H, Aoki T, Nakamura Y, Hiramatsu Y, Kobayashi S, Gabata T

    Magnetic resonance imaging   Vol. 50   page: 61-67   2018.7

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    Language:English  

    DOI: 10.1016/j.mri.2018.03.013

    PubMed

  8. Utility of the variable flip angle 3D fast-spin echo (isoFSE) sequence on 3T MR for diagnosing vertebrobasilar artery dissection. Reviewed

    Ogawa M, Omata S, Kan H, Arai N, Asai M, Urano M, Shibamoto Y

    Radiological physics and technology   Vol. 11 ( 2 ) page: 228-234   2018.6

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    DOI: 10.1007/s12194-018-0460-7

    PubMed

  9. Novel practical SNR determination method for MRI using double echo with longest second echo time (DELSET). Reviewed

    Ohno N, Miyati T, Niwa Y, Kan H, Ishida S, Kasai H, Shibamoto Y, Gabata T

    The British journal of radiology   Vol. 91 ( 1086 ) page: 20170652   2018.6

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    Language:English  

    DOI: 10.1259/bjr.20170652

    PubMed

  10. Time-resolved magnetic resonance angiography as a follow-up method for visceral artery aneurysm treated with coil-embolisation. Reviewed

    Kawai T, Shimohira M, Suzuki K, Ohta K, Kurosaka K, Hashizume T, Nishikawa H, Muto M, Arai N, Kan H, Shibamoto Y

    Polish journal of radiology   Vol. 83   page: e137-e142   2018

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    DOI: 10.5114/pjr.2018.75622

    PubMed

  11. Quantitative susceptibility mapping using principles of echo shifting with a train of observations sequence on 1.5T MRI. Reviewed

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

    Magnetic resonance imaging   Vol. 42   page: 37-42   2017.10

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    DOI: 10.1016/j.mri.2017.05.002

    PubMed

  12. Water and lipid diffusion MRI using chemical shift displacement-based separation of lipid tissue (SPLIT). Reviewed

    Ohno N, Kan H, Miyati T, Aoki T, Ishida S, Gabata T

    Magnetic resonance imaging   Vol. 39   page: 144-148   2017.6

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    DOI: 10.1016/j.mri.2017.02.006

    PubMed

  13. Background field removal technique using regularization enabled sophisticated harmonic artifact reduction for phase data with varying kernel sizes. Reviewed

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

    Magnetic resonance imaging   Vol. 34 ( 7 ) page: 1026-33   2016.9

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    DOI: 10.1016/j.mri.2016.04.019

    PubMed

  14. Insular Volume Reduction in Patients with Social Anxiety Disorder. Reviewed

    Kawaguchi A, Nemoto K, Nakaaki S, Kawaguchi T, Kan H, Arai N, Shiraishi N, Hashimoto N, Akechi T

    Frontiers in psychiatry   Vol. 7   page: 3   2016

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    DOI: 10.3389/fpsyt.2016.00003

    PubMed

  15. Shortened breath-hold contrast-enhanced MRI of the liver using a new parallel imaging technique, CAIPIRINHA (controlled aliasing in parallel imaging results in higher acceleration): a comparison with conventional GRAPPA technique. Reviewed

    Ogawa M, Kawai T, Kan H, Kobayashi S, Akagawa Y, Suzuki K, Nojiri S, Ozawa Y, Shibamoto Y

    Abdominal imaging   Vol. 40 ( 8 ) page: 3091-8   2015.10

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    Language:English  

    DOI: 10.1007/s00261-015-0491-z

    PubMed

  16. Dynamic state of water molecular displacement of the brain during the cardiac cycle in idiopathic normal pressure hydrocephalus. Reviewed

    Kan H, Miyati T, Mase M, Osawa T, Ohno N, Kasai H, Arai N, Kawano M, Shibamoto Y

    Computerized medical imaging and graphics : the official journal of the Computerized Medical Imaging Society   Vol. 40   page: 88-93   2015.3

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  17. Transfer characteristics of arterial pulsatile force in regional intracranial tissue using dynamic diffusion MRI: a phantom study. Reviewed

    Kan H, Miyati T, Kasai H, Arai N, Ohno N, Mase M, Shibamoto Y

    Magnetic resonance imaging   Vol. 32 ( 10 ) page: 1284-9   2014.12

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    DOI: 10.1016/j.mri.2014.08.026

    PubMed

  18. Feasibility of time-resolved MR angiography for detecting recanalization of pulmonary arteriovenous malformations treated with embolization with platinum coils. Reviewed

    Kawai T, Shimohira M, Kan H, Hashizume T, Ohta K, Kurosaka K, Muto M, Suzuki K, Shibamoto Y

    Journal of vascular and interventional radiology : JVIR   Vol. 25 ( 9 ) page: 1339-47   2014.9

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    DOI: 10.1016/j.jvir.2014.06.003

    PubMed

  19. A method for assessing metabolic information on liver and bone marrow by use of double gradient-echo with spectral fat suppression. Reviewed

    Kasai H, Miyati T, Kawai T, Kan H, Kawano M, Shibamoto Y

    Radiological physics and technology   Vol. 7 ( 2 ) page: 211-6   2014.7

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    Language:English  

    DOI: 10.1007/s12194-013-0254-x

    PubMed

  20. Idiopathic normal-pressure hydrocephalus: temporal changes in ADC during cardiac cycle. Reviewed

    Ohno N, Miyati T, Mase M, Osawa T, Kan H, Kasai H, Hara M, Shibamoto Y, Hayashi N, Gabata T, Matsui O

    Radiology   Vol. 261 ( 2 ) page: 560-5   2011.11

     More details

    Language:English  

    DOI: 10.1148/radiol.11101860

    PubMed

  21. [Appropriate cardiac phase for measurement of ADC of the brain using ECG-triggered diffusion MRI]. Reviewed

    Kan H, Miyati T, Mase M, Kasai H, Hara M, Shibamoto Y, Kawano M, Ohno N, Kitanaka A, Yorimitsu R, Minami T

    Nihon Hoshasen Gijutsu Gakkai zasshi   Vol. 67 ( 6 ) page: 661-5   2011

     More details

    Language:Japanese  

    PubMed

  22. [Analyses of restricted diffusion of water molecules using trabecular bone phantom]. Reviewed

    Minami T, Miyati T, Ueda Y, Kan H, Kitanaka A, Kasai H, Arai N, Hara M, Shibamoto Y, Yokoti S

    Nihon Hoshasen Gijutsu Gakkai zasshi   Vol. 67 ( 6 ) page: 634-9   2011

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    PubMed

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KAKENHI (Grants-in-Aid for Scientific Research) 5

  1. 加齢による脳局所の血液脳関門の機能障害と鉄沈着の関係解明

    Grant number:23K07107  2023.4 - 2026.3

    科学研究費助成事業  基盤研究(C)

    菅 博人

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    Authorship:Principal investigator 

    Grant amount:\4680000 ( Direct Cost: \3600000 、 Indirect Cost:\1080000 )

  2. 安静時fMRIを用いたiNPH診療の新たなイメージングバイオマーカーの探求

    Grant number:22K09211  2022.4 - 2025.3

    科学研究費助成事業  基盤研究(C)

    山田 紘史, 山中 智康, 間瀬 光人, 菅 博人

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    Authorship:Coinvestigator(s) 

    iNPHは認知量の5%を占めるとされる。髄液シャント術で症状が改善するが、高齢や他疾患の背景から、治療効果が一定せず、治療を躊躇われる場合も多い。本研究は、安静時機能的MRI(rs-fMRI)を用い、iNPH診療において、①神経症候(高次脳や運動機能)と術前rs-fMRIでの異常な脳内ネットワークとの関係性、②術後改善する神経症候とrs-fMRIでの変化との関係性を評価し、「病態および治療の要となる脳機能ネットワークの異常とは何か」を検証する。iNPH診療における手術による脳機能改善効果を予測する指標として、rs-fMRIが簡易で非侵襲的な新しいイメージングバイオマーカーとなる可能性がある。

  3. MR単独治療計画における定量的磁化率画像を利用した画像誘導放射線治療法の確立

    Grant number:20K16786  2020.4 - 2023.3

    日本学術振興会  科学研究費助成事業  若手研究

    菅 博人

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount:\3900000 ( Direct Cost: \3000000 、 Indirect Cost:\900000 )

    前立腺癌のMR単独放射線治療計画における定量的磁化率画像を利用した画像誘導放射線治療法の確立および,前立腺における定量的磁化率画像の再構成法の開発を目的としている.現在,MR単独放射線治療計画には金属マーカーなどの埋め込みが必要とされており,侵襲的である.また前立腺に対する定量的磁化率画像の再構成法はゴールドスタンダードがなく,放射線治療に利用できる画質は得られていない.
    MR単独放射線治療計画の画像誘導放射線治療のために石灰化を描出できる定量的磁化率画像を利用し,従来法と比較してその有用性を明らかにするとともに前立腺における定量的磁化率画像の再構成法の開発を行う.
    本年度は対象となる被検者画像の収集および解析の準備と定量的磁化率画像の再構成法の検討を中心に行った.
    被検者の画像は現在も収集中であるが,おおむね目標数を達成することができ,解析の準備を進めている.具体的には放射線治療計画用CTおよびMR単独放射線治療用のPseudo-CT画像の収集,実際の放射線治療時の画像誘導放射線治療に使用されたコーンビームCTを放射線治療計画装置に取り込みを行った.また放射線治療計画装置に収集されたPseudo-CTとCT画像それぞれに前立腺周囲の主要な臓器をコンツーリングし両画像の撮影タイミングが違うことによって生じる幾何学的位置ずれを非剛体レジストレーションを用いて補正を行った.
    一方,定量的磁化率画像の再構成は信号雑音比の悪い位相画像の位相展開を正確に行うことは非常に難しく,より効果的に行える位相展開の方法についての検討を行っている.それに加えて背景磁場抑制の手法についても現在検討を重ねている.
    さらに定量的磁化率画像と同じデータから再構成可能なR2スター画像やマルチコンポーネントR2スター解析を利用した方法も利用できないか検討を重ねており,石灰化の描出に焦点を当てれば比較的正確に描出可能であることが分かった.
    そのため定量的磁化率画像が作成できるようになったのちはR2スター,マルチコンポーネントR2スター解析から得られた石灰化像のいずれの画像がより今回の目的に適しているか再検討する予定である.
    本年度は対象となる被検者画像の収集および解析の準備と定量的磁化率画像の再構成法の検討を中心に行った.
    被検者の画像収集は現在も収集中であるが,概ね目標の人数に達しており,解析に必要なグラディエントエコー法から得た強度および位相画像,同時に収集されたCT画像はすでに実際の解析を行う放射線治療計画装置内へ取り込み済みである.また被検者の放射線治療時に取得される画像誘導放射線治療用のコーンビームCTも各被検者に対して5~7フラクションを放射線知慮装置から取り込みを開始している.またCT画像とMR単独放射線治療用Pseudo-CT画像の撮像タイミングの違いによる臓器位置のズレを一致させるためにDeformable registrationを行うが,そのためにCT,Pseudo-CT画像上に臓器ごとのコンツーリングを半数程度の患者にて行っている状況である.
    一方,定量的磁化率画像の再構成方法については,CT画像とほぼ同じ高分解能のグラディエントエコー法から得た強度および位相画像から画像処理作成を試みている.定量的磁化率画像の再構成方法に関しては信号雑音比の悪い位相画像の位相展開を正確に行うことが難しく,やや難航している.また同じ画像からR2スター画像,マルチコンポーネントR2スター解析画像を作成であることが分かったためそちらも同時に検討している.以上のように画像作成方法の準備がやや遅れている.
    より正確に石灰化を描出できると予想される定量的磁化率画像のほかにR2スター画像,マルチコンポーネントR2スター解析画像を含めて,描出される石灰化サイズをCT画像と比較し,より正確な画像化を目指す.
    それとともに対象患者のデータをまとめて2022年度後半に石灰化を利用したMR
    MR単独放射線治療における画像誘導放射線治療の有用性の解析を始められるように準備をする.

  4. 肺動静脈奇形に対する塞栓術後の新たな画像診断:造影剤を使用しない非侵襲的血流評価

    Grant number:20K08002  2020.4 - 2023.3

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    下平 政史, 中川 基生, 富田 夏夫, 荒井 信行, 河合 辰哉, 菅 博人, 小澤 良之

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    Authorship:Coinvestigator(s)  Grant type:Competitive

    肺動静脈奇形に対するコイル塞栓術後の再開通は、脳梗塞の原因となるため、その診断は重要である。私たちは、Time resoloved MR angiography (TR-MRA)という正診率の高い新たな診断方法を開発し世界に先駆けて報告した。しかし、これは造影剤を静脈注射する方法であり、有害事象を生じる可能性があった。そこで本研究では、正確に診断できる非造影MRAの撮影方法を樹立し、肺動静脈奇形に対する塞栓術後の非侵襲的な再開通の診断方法を確立する。
    本研究における研究実施計画書を作成し、研究倫理審査委員会の承認を得た。次に、ファントム実験のための脈動ポンプを購入し、初期実験を行った。この結果、脈動ポンプを使用すれば、肺動脈の血流を十分に再現できることが明らかとなった。ファントムの作成に必要な機材も購入済みであり、今後、どのようなファントムが適切であるかを検証し、ファントム作成に取り組む。ファントムが作成されれば、上記の脈動ポンプと組み合わせ、ファントムの本実験を行う。その後、さらに検証を重ね、ファントムを用いたMRAの撮影実験を行い、至適プロトコールを構築していく。次の段階として、コイルをファントム内に留置し、仮想の塞栓後の肺動静脈奇形モデルおよび再開通を生じた肺動静脈奇形モデルを作成し、再発診断への応用の可能性を検討する。
    一方、これまでの経験をもとに非造影MRAのプロトコールを作成・ブラッシュアップし、これまでに3例の肺動静脈奇形の塞栓術前の症例にて撮影を実施した。いずれも問題なく検査を完遂することができた。結果として、造影剤を使用するTime resoloved MR angiography (TR-MRA)との比較では、3例中2例は、非造影MRAの画像はTR-MRAの画像に比し、優位に不良であった。これは、患者の年齢や呼吸状態により息止めが十分に得られず、画質に影響したものと考えられる。一方、残りの1例では、TR-MRAに遜色のない画像が得られた。これにより条件が整えば、非造影でも十分な画像が得られる可能性が示唆された。
    今後はファントム実験を進め、至適プロトコールを探るとともに、臨床にて症例集積し、さらなるデータの集積に努める。
    予定通り、脈動ポンプを購入し、これを使用した初期実験に成功することができた。
    また、臨床でも3例に非造影MRAを安全に施行でき、安全性・実行可能性が示唆された。
    引き続きファントム実験を重ねるとともに、臨床にてデータ集積を続ける。

  5. Development of novel temperature imaging using quantitative susceptibility mapping

    Grant number:17K15805  2017.4 - 2021.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists (B)

    Kan Hirohito

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount:\4030000 ( Direct Cost: \3100000 、 Indirect Cost:\930000 )

    This study assumed that the susceptibility value estimated by quantitative susceptibility mapping (QSM) has temperature dependence. Investigating the relationship between susceptibility and temperature leads to a novel temperature imaging of the brain. The susceptibility value was inversely correlated with temperature. The decreasing susceptibility rate with temperature is affected more by the larger susceptibility values in the specific pixel.
    Using these results, we proposed the equation between susceptibility and temperature. Also, twice measurements i.e., the baseline and abnormal temperature, are needed to provide the temperature imaging based on QSM.