Fujiwara, Hirokazu

写真a

Affiliation

School of Medicine, Center for Preventive Medicine (Shinanomachi)

Position

Assistant Professor/Senior Assistant Professor

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Research Areas 【 Display / hide 】

  • Life Science / Radiological sciences

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Research Keywords 【 Display / hide 】

  • neuroradiology

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Papers 【 Display / hide 】

  • Non-lesional white matter changes depicted by q-space diffusional MRI correlate with clinical disabilities in multiple sclerosis

    Motegi H., Kufukihara K., Kitagawa S., Sekiguchi K., Hata J., Fujiwara H., Jinzaki M., Okano H., Nakamura M., Iguchi Y., Nakahara J.

    Journal of the Neurological Sciences (Journal of the Neurological Sciences)  456 2024.01

    ISSN  0022510X

    　View Summary

    Background: We previously developed an optimized q-space diffusional MRI technique (normalized leptokurtic diffusion [NLD] map) to delineate the demyelinated lesions of multiple sclerosis (MS) patients. Herein, we evaluated the utility of NLD maps to discern the white matter abnormalities in normal-appearing white matter (NAWM) and the abnormalities' possible associations with physical and cognitive disabilities in MS. Methods: We conducted a retrospective observational study of MS patients treated at our hospital (Jan. 2012 to Dec. 2022). Clinical and MRI data were collected; Processing Speed Test (PST) data were obtained when possible. For a quantitative analysis of the NLD maps, we calculated the NLD index as GVROI/GVREF, where GV is a mean grayscale value in the regions of interest (ROIs) and the reference area (REF; cerebrospinal fluid). Results: One hundred-one individuals with MS were included. The lower corpus callosum and non-lesional WM NLD index were associated with worse Expanded Disability Status Scale (EDSS) and PST scores. The NLD indexes in the corpus callosum (p < 0.0001) and non-lesional white matter (p < 0.0001) were significantly reduced in progressive MS compared to relapsing-remitting MS. We categorized MS severity as moderate/severe (EDSS score ≥ 4 points) and mild (EDSS score < 4 points). The NLD indexes in the corpus callosum (p < 0.0001) and non-lesional white matter (p < 0.0001) were significantly lower in the moderate/severe MS group compared to the mild MS group. Conclusion: The NLD map revealed abnormalities in the non-lesional white matter, providing valuable insights for evaluating manifestations in MS patients.

  • “Missing-piece” sign with dural arteriovenous fistula at craniocervical junction: A case report

    Tezuka T., Nukariya T., Katsumata M., Miyauchi T., Tokuyasu D., Azami S., Izawa Y., Nagoshi N., Fujiwara H., Mizutani K., Akiyama T., Toda M., Nakahara J., Nishimoto Y.

    Journal of Stroke and Cerebrovascular Diseases (Journal of Stroke and Cerebrovascular Diseases)  32 ( 7 )  2023.07

    ISSN  10523057

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    Objectives: Spinal dural arteriovenous fistula (sDAVF) is a rare and often underdiagnosed spinal disease. Early diagnosis is required because the deficits are reversible and delays in treatment cause permanent morbidity. Although the abnormal vascular flow void is a critical radiographic feature of sDAVF, they are not always present. A characteristic enhancement pattern of sDAVF has been recently reported as the “missing-piece” sign which can lead to the early and correct diagnosis. Methods: We presented imaging findings, treatment decisions, and the outcome of a rare case of sDAVF, in which the “missing-piece” sign appeared atypical. Results: A 60-year-old woman developed numbness and weakness in her extremities. Spinal MRI revealed longitudinal hyperintensity in the T2-weighted image, extending from the thoracic level to medulla oblongata. At first, myelopathy with inflammation or tumor was suspected because of the lack of flow voids and vascular abnormalities in CT-angiography and MR-DSA. However, we administered intravenous methylprednisolone and her symptom got worse with the appearance of the “missing-piece” sign. Then, we successfully diagnosed sDAVF by angiography. The “missing-piece” sign was considered to derive from inconsistency of the intrinsic venous system of spinal cord, with the abrupt segments without enhancement. The same etiology was considered in our case. Conclusions: Detecting the “missing-piece” sign can lead to the correct diagnosis of sDAVF, even if the sign appeared atypical.

  • Changes in cross-sectional areas of posterior extensor muscles in thoracic spine: a 10-year longitudinal MRI study

    Umezawa H., Daimon K., Fujiwara H., Nishiwaki Y., Michikawa T., Okada E., Nojiri K., Watanabe M., Katoh H., Shimizu K., Ishihama H., Fujita N., Tsuji T., Nakamura M., Matsumoto M., Watanabe K.

    Scientific Reports (Scientific Reports)  12 ( 1 )  2022.12

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    Age-related changes in the posterior extensor muscles of the cervical and lumbar spine have been reported in some studies; however, longitudinal changes in the thoracic spine of healthy subjects are rarely reported. Therefore, this study aimed to evaluate changes in the cross-sectional areas (CSAs) of posterior extensor muscles in the thoracic spine over 10 years and identify related factors. The subjects of this study were 85 volunteers (mean age: 44.7 ± 11.5) and the average follow-up period was about 10 years. The CSAs of the transversospinalis muscles, erector spinae muscles, and total CSAs of the extensor muscles from T1/2 to T11/12 were measured on magnetic resonance imaging. The extent of muscle fat infiltration was assessed by the signal intensity (luminance) of the extensor muscles’ total cross-section compared to a section of pure muscle. We applied a Poisson regression model, which is included in the generalized linear model, and first examined the univariate (crude) association between each relevant factor (age, sex, body mass index, lifestyle, back pain, neck pain, neck stiffness, and intervertebral disc degeneration) and CSA changes. Then, we constructed a multivariate model, which included age, sex, and related factors in the univariate analysis. The mean CSAs of the transversospinalis muscles, erector spinae muscles, and total CSAs of the extensor muscles significantly increased over 10 years. Exercise habit was associated with increased CSAs of the erector spinae muscles and the total area of the extensor muscles. The cross-section mean luminance significantly increased from baseline, indicating a significant increase of fat infiltration in the posterior extensor muscles. Progression of disc degeneration was inversely associated with increased fat infiltration in the total extensor muscles.

  • Cranial defect and pneumocephalus are associated with significant postneurosurgical positional brain shift: evaluation using upright computed tomography

    Yoshida K., Toda M., Yamada Y., Yamada M., Yokoyama Y., Tsutsumi K., Fujiwara H., Kosugi K., Jinzaki M.

    Scientific Reports (Scientific Reports)  12 ( 1 )  2022.12

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    Only few studies have assessed brain shift caused by positional change. This study aimed to identify factors correlated with a large postneurosurgical positional brain shift (PBS). Sixty-seven patients who underwent neurosurgical procedures had upright computed tomography (CT) scan using settings similar to those of conventional supine CT. The presence of a clinically significant PBS, defined as a brain shift of ≥ 5 mm caused by positional change, was evaluated. The clinical and radiological findings were investigated to identify factors associated with a larger PBS. As a result, twenty-one patients had a clinically significant PBS. The univariate analysis showed that supratentorial lesion location, intra-axial lesion type, craniectomy procedure, and residual intracranial air were the predictors of PBS. Based on the multivariate analysis, craniectomy procedure (p < 0.001) and residual intracranial air volume (p = 0.004) were the predictors of PBS. In a sub-analysis of post-craniectomy patients, PBS was larger in patients with supratentorial craniectomy site and parenchymal brain injury. A large craniectomy area and long interval from craniectomy were correlated with the extent of PBS. In conclusion, patients who undergo craniectomy and those with residual intracranial air can present with a large PBS. In post-craniectomy patients, the predisposing factors of a large PBS are supratentorial craniectomy, presence of parenchymal injury, large skull defect area, and long interval from craniectomy. These findings can contribute to safe mobilization among postneurosurgical patients and the risk assessment of sinking skin flap syndrome.

  • Synthetic magnetic resonance imaging for primary prostate cancer evaluation: Diagnostic potential of a non-contrast-enhanced bi-parametric approach enhanced with relaxometry measurements

    Arita Y., Akita H., Fujiwara H., Hashimoto M., Shigeta K., Kwee T.C., Yoshida S., Kosaka T., Okuda S., Oya M., Jinzaki M.

    European Journal of Radiology Open (European Journal of Radiology Open)  9 2022.01

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    Purpose: Bi-parametric magnetic resonance imaging (bpMRI) with diffusion-weighted images has wide utility in diagnosing clinically significant prostate cancer (csPCa). However, bpMRI yields more false-negatives for PI-RADS category 3 lesions than multiparametric (mp)MRI with dynamic-contrast-enhanced (DCE)-MRI. We investigated the utility of synthetic MRI with relaxometry maps for bpMRI-based diagnosis of csPCa. Methods: One hundred and five treatment-naïve patients who underwent mpMRI and synthetic MRI before prostate biopsy for suspected PCa between August 2019 and December 2020 were prospectively included. Three experts and three basic prostate radiologists evaluated the diagnostic performance of conventional bpMRI and synthetic bpMRI for csPCa. PI-RADS version 2.1 category 3 lesions were identified by consensus, and relaxometry measurements (T1-value, T2-value, and proton density [PD]) were performed. The diagnostic performance of relaxometry measurements for PI-RADS category 3 lesions in peripheral zone was compared with that of DCE-MRI. Histopathological evaluation results were used as the reference standard. Statistical analysis was performed using the areas under the receiver operating characteristic curve (AUC) and McNemar test. Results: In 102 patients without significant MRI artefacts, the diagnostic performance of conventional bpMRI was not significantly different from that of synthetic bpMRI for all readers (p = 0.11–0.79). The AUCs of the combination of T1-value, T2-value, and PD (T1 + T2 + PD) for csPCa in peripheral zone for PI-RADS category 3 lesions were 0.85 for expert and 0.86 for basic radiologists, with no significant difference between T1 + T2 + PD and DCE-MRI for both expert and basic radiologists (p = 0.29–0.45). Conclusion: Synthetic MRI with relaxometry maps shows promise for contrast media-free evaluation of csPCa.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Reviews, Commentaries, etc. 【 Display / hide 】

  • Author Correction: A VEGF receptor vaccine demonstrates preliminary efficacy in neurofibromatosis type 2 (Nature Communications, (2019), 10, 1, (5758), 10.1038/s41467-019-13640-1)

    Tamura R., Fujioka M., Morimoto Y., Ohara K., Kosugi K., Oishi Y., Sato M., Ueda R., Fujiwara H., Hikichi T., Noji S., Oishi N., Ogawa K., Kawakami Y., Ohira T., Yoshida K., Toda M.

    Nature Communications (Nature Communications)  11 ( 1 )  2020.12

    　View Summary

    The original version of this Article omitted from the author list the 10th author Tetsuro Hikichi, who is from OncoTherapy Science, Inc., 3-2-1, Sakado, Takatsu-ku, Kawasaki City, Kanagawa, 213-0012, Japan. This author has been added to the article. Consequently, the 5th sentence in the Authors Contributions has been modified to read “RT, MF, YM, KO, KK, YO, MS, NO, HF, TH, and SN collected the data”. Additionally, the following was added to the Competing Interests: TH is an employee of OncoTherapy Science, Inc. This has been corrected in both the PDF and HTML versions of the Article.

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Presentations 【 Display / hide 】

  • Evolution of AI and clinical application of MR deep learning　-Neuro Imaging

    藤原広和

    第80回日本放射線学会, 

    2021.04
    , 

    Oral presentation (invited, special)

  • Synthetic MRIの臨床・研究への応用 (臨床編）

    藤原広和

    第50回神経放射線学会 (大阪) , 

    2021.02
    , 

    Oral presentation (invited, special)

  • Acquisition time reduction of MR neuromelanin imaging using deep-learning based reconstruction

    堤 啓, 藤原 広和, 長谷 学, 南 康大, 野崎 敦, 布川 嘉信, 奥田 茂男, 陣崎 雅弘

    第48回日本磁気共鳴医学会大会 (盛岡) , 

    2020.09
    , 

    Poster presentation

  • 頭部MRI上のアーチファクトと病変との鑑別　適切な診断と治療のために

    藤原広和

    第40回2007カンファレンス (川崎) , 

    2019.07
    , 

    Oral presentation (invited, special)

  • 胸椎後方伸筋群の横断面積のMRIによる10年間の縦断的研究

    梅澤 仁, 大門 憲史, 藤原 広和, 岡田 英次朗, 野尻 賢哉, 加藤 裕幸, 清水 健太郎, 石濱 寛子, 藤田 順之, 辻 崇, 中村 雅也, 松本 守雄, 渡辺 航太

    第48回日本脊椎脊髄病学会, 

    2019.04
    , 

    Oral presentation (general)

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Courses Taught 【 Display / hide 】

  • LECTURE SERIES, INTERNAL MEDICINE (NEUROLOGY)

    2024

  • LECTURE SERIES, RADIOLOGY

    2023

  • LECTURE SERIES, INTERNAL MEDICINE (NEUROLOGY)

    2023

  • LECTURE SERIES, INTERNAL MEDICINE

    2023

  • INTRODUCTION TO CLINICAL CLERKSHIPS

    2023

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Courses Previously Taught 【 Display / hide 】

  • neuroimaging

    Keio University

    2018.04
    -
    2019.03
    , 

    Seminar

  • neurology imaging

    Keio University

    2018.04
    -
    2019.03
    , 

    Lecture

  • 放射線診断学

    Keio University

    2018.04
    -
    2019.03
    , 

    Full academic year, Lecture, Within own ｆaculty, 100people

  • 放射線診断学系統講義

    Keio University

    2017.04
    -
    2018.03
    , 

    Full academic year, Lecture, 100people

  • 放射線診断学

    Keio University

    2017.04
    -
    2018.03
    , 

    Full academic year, Lecture, Within own ｆaculty, 100people

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