Fujiwara, Hirokazu



School of Medicine, Department of Radiology (Diagnostic Radiology) (Shinanomachi)


Assistant Professor/Senior Assistant Professor

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Research Areas 【 Display / hide

  • Radiation science

Research Keywords 【 Display / hide

  • neuroradiology


Papers 【 Display / hide

  • Effect of gravity on brain structure as indicated on upright computed tomography

    Yokoyama Y., Yamada Y., Kosugi K., Yamada M., Narita K., Nakahara T., Fujiwara H., Toda M., Jinzaki M.

    Scientific Reports (Scientific Reports)  11 ( 1 )  2021.12

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    We aimed to use upright computed tomography (CT) to depict posture-related changes in the brain tissue under normal gravity. Thirty-two asymptomatic volunteers underwent upright CT in the sitting position and conventional CT in the supine position on the same day. We compared the shift of the pineal body, cerebellar tonsil, the length of pituitary stalk, optic nerve sheath area and perimeter (ONSA and ONSP, respectively), and lateral ventricular volume between the supine and sitting positions. We also compared shape changes of the cerebrospinal fluid (CSF) spaces at different sites between both positions. In the sitting position, the pineal body shifted 0.68 ± 0.27 mm in the ventral direction and 0.76 ± 0.24 mm in the caudal direction, the length of pituitary stalk decreased by 1.23 ± 0.71 mm, the cerebellar tonsil descended by 2.10 ± 0.86 mm, the right ONSA decreased by 15.21 ± 6.54%, the left ONSA decreased by 15.30 ± 7.37%, the right ONSP decreased by 8.52 ± 3.91%, the left ONSP decreased by 8.20 ± 4.38%, and the lateral ventricular volume decreased by 5.07 ± 3.24% (all P < 0.001). We also observed changes in the shape of CSF spaces with changes in posture. We concluded that the intracranial structure of healthy subjects and volume of ventricles changed according to posture on Earth.

  • Orthostatic Enlargement of a Supracerebellar Arachnoid Cyst With Cerebellar Descent Visualized by Upright Computed Tomography

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

    World Neurosurgery (World Neurosurgery)  145   256 - 259 2021.01

    ISSN  18788750

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    Background: Posterior fossa arachnoid cysts are often asymptomatic, but can rarely cause postural headache, the mechanism of which remains unknown. Case Description: We present a 40-year-old woman with an asymptomatic supracerebellar arachnoid cyst. Upright computed tomography (CT) showed enlargement of the arachnoid cyst and caudal descent of the cerebellum compared with supine CT with narrowing of the craniocervical junction cerebrospinal fluid space. Conclusions: This finding aids in understanding the association of posterior fossa arachnoid cysts with orthostatic headache. Clinicians should be aware of possible posture-related changes in intracranial structures.

  • The Long-Term Impact of Whiplash Injuries on Patient Symptoms and the Associated Degenerative Changes Detected Using MRI A Prospective 20-Year follow-up Study Comparing Patients with Whiplash-Associated Disorders with Asymptomatic Subjects

    Watanabe, Kota MD, PhDa; Daimon, Kenshi MD, PhDa; Fujiwara, Hirokazu MD, PhDb; Nishiwaki, Yuji MD, PhDc; Okada, Eijiro MD, PhDa; Nojiri, Kenya MD, PhDd; Watanabe, Masahiko MD, PhDi; Katoh, Hiroyuki MD, PhDi; Shimizu, Kentaro MD, PhDe; Ishihama, Hiroko MDe; Fujita, Nobuyuki MD, PhDg; Ichihara, Daisuke MD, PhDf; Tsuji, Takashi MD, PhDh; Nakamura, Masaya MD, PhDa; Matsumoto, Morio MD, PhD

    Spine (Spine)   2020.12

  • Posture-induced changes in the vessels of the head and neck: evaluation using conventional supine CT and upright CT

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

    Scientific Reports (Scientific Reports)  10 ( 1 )  2020.12

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    Since the venous system is affected by gravity, upright computed tomography (CT) in addition to conventional supine CT has great potential for evaluating postural changes in the venous system. We evaluated the morphological differences in the head and neck vessels by performing a contrast CT study in both the supine and the sitting positions. In this study, the 20 included participants (10 men and 10 women) were healthy adults aged 30 to 55 years. The cross-sectional area of the cervical vessels, craniocervical junction veins, and intracranial vessels were obtained quantitatively. Venous sinuses and venous plexuses that were difficult to measure were evaluated qualitatively. The average change in areas from a supine to an upright posture was − 77.87 ± 15.99% (P < 0.0001) in the right internal jugular vein (IJV), − 69.42 ± 23.15% (P < 0.0001) in the left IJV, − 61.52 ± 12.81% (P < 0.0001) in the right external jugular vein (EJV), and − 58.91 ± 17.37% (P < 0.0001) in the left EJV. In contrast, the change in the anterior condylar vein (ACV) from a supine to an upright posture was approximately + 144% (P < 0.005) on the right side and + 110% (P < 0.05) on the left side. In addition, according to the qualitative analysis, the posterior venous structures including the anterior condylar confluence (ACC) of the craniocervical junction became more prominent in an upright posture. Despite these changes, the intracranial vessels showed almost no change between postures. From a supine to an upright position, the IJVs and EJVs above the heart collapsed, and venous channels including the ACCs and ACVs opened, switching the main cerebral venous drainage from the IJVs to the vertebral venous system. Upright head CT angiography can be useful for investigating physiological and pathophysiological hemodynamics of the venous system accompanying postural changes.

  • 123-IMP single-photon emission computed tomography imaging in visual snow syndrome: A case series

    Shibata M., Tsutsumi K., Iwabuchi Y., Kameyama M., Takizawa T., Nakahara T., Fujiwara H., Jinzaki M., Nakahara J., Dodick D.W.

    Cephalalgia (Cephalalgia)  40 ( 14 ) 1671 - 1675 2020.12

    ISSN  03331024

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    Background: Visual snow syndrome (VSS) is a neurological condition characterized by persistent flickering dots in the visual fields, palinopsia, enhanced entoptic phenomenon, photophobia, and nyctalopia. Neuroimaging evidence supports the role of the visual association cortex in visual snow syndrome. Case series: We provided clinical care to three patients with visual snow syndrome, in whom [ I]-IMP single-photon emission computed tomography (SPECT) imaging was performed. Case 1 was a 21-year-old male with a past history of migraine with aura who exhibited visual snow and entoptic phenomenon. In this patient, [ I]-IMP SPECT imaging revealed right occipital and temporal hypoperfusion with a distribution matching the ventral visual stream. [ I]-IMP SPECT imaging detected only mild bilateral frontal hypoperfusion in Case 2 and no overt abnormalities in Case 3. Conclusion: Although visual snow syndrome seems to be a heterogenous condition, our observations indicate that abnormal visual processing within the ventral visual stream may play a role in the pathogenesis of this condition. 123 123 123

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

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.

Presentations 【 Display / hide

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


    第80回日本放射線学会, 2021.04, Oral Presentation(guest/special)

  • Synthetic MRIの臨床・研究への応用 (臨床編)


    第50回神経放射線学会 (大阪) , 2021.02, Oral Presentation(guest/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 (general)

  • 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


    第40回2007カンファレンス (川崎) , 2019.07, Oral Presentation(guest/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











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Courses Previously Taught 【 Display / hide

  • neuroimaging

    Keio University, 2018, Seminar

  • neurology imaging

    Keio University, 2018, Major subject, Lecture

  • 放射線診断学

    Keio University, 2018, Full academic year, Major subject, Lecture, Within own faculty, 100people

  • 放射線診断学系統講義

    Keio University, 2017, Full academic year, Major subject, Lecture, 100people

  • 放射線診断学

    Keio University, 2017, Full academic year, Major subject, Lecture, Within own faculty, 100people

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