Nakahara, Takehiro



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


Project Assistant Professor (Non-tenured)/Project Research Associate (Non-tenured)/Project Instructor (Non-tenured)

Academic Background 【 Display / hide

  • 1997.04

    Gunma University, 医学部, 医学科

    University, Graduated, Master's course

  • 2007.04

    Gunma University, 医学系研究科

    Graduate School, Graduated, Doctoral course

Licenses and Qualifications 【 Display / hide

  • medical doctor, 2003.04

  • Board Certified Member of the Japanese Society of Internal Medicine, 2006

  • Board Certified Member of the Japanese Circulation Society, 2010

  • MD-PhD, 2010.03

  • The Japanese Board of Nuclear Medicine, 2013

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Research Areas 【 Display / hide

  • Cardiovascular medicine

  • Molecular biology

  • Radiation science

Research Keywords 【 Display / hide

  • 動脈硬化

  • cardiovascular imaging

Research Themes 【 Display / hide

  • 動脈硬化, 


  • molecular imaging, 



Papers 【 Display / hide

  • Three-dimensional evaluation of the coccyx movement between supine and standing positions using conventional and upright computed tomography imaging

    Yagi F., Yamada Y., Yamada M., Yokoyama Y., Mukai K., Nakahara T., Narita K., Jinzaki M.

    Scientific Reports (Scientific Reports)  11 ( 1 )  2021.12

     View Summary

    Currently, no three-dimensional reference data exist for the normal coccyx in the standing position on computed tomography (CT); however, this information could have utility for evaluating patients with coccydynia and pelvic floor dysfunction. Thus, we aimed to compare coccygeal parameters in the standing versus supine positions using upright and supine CT and evaluate the effects of sex, age, and body mass index (BMI) on coccygeal movement. Thirty-two healthy volunteers underwent both upright (standing position) and conventional (supine position) CT examinations. In the standing position, the coccyx became significantly longer and straighter, with the tip of the coccyx moving backward and downward (all p < 0.001). Additionally, the coccygeal straight length (standing/supine, 37.8 ± 7.1/35.7 ± 7.0 mm) and sacrococcygeal straight length (standing/supine, 131.7 ± 11.2/125.0 ± 10.7 mm) were significantly longer in the standing position. The sacrococcygeal angle (standing/supine, 115.0 ± 10.6/105.0 ± 12.5°) was significantly larger, while the lumbosacral angle (standing/supine, 21.1 ± 5.9/25.0 ± 4.9°) was significantly smaller. The migration length of the tip of the coccyx (mean, 7.9 mm) exhibited a moderate correlation with BMI (r = 0.42, p = 0.0163). Our results may provide important clues regarding the pathogenesis of coccydynia and pelvic floor dysfunction.

  • 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

     View Summary

    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.

  • JCS 2018 Guideline on Diagnosis of Chronic Coronary Heart Diseases

    Yamagishi M., Tamaki N., Akasaka T., Ikeda T., Ueshima K., Uemura S., Otsuji Y., Kihara Y., Kimura K., Kimura T., Kusama Y., Kumita S., Sakuma H., Jinzaki M., Daida H., Takeishi Y., Tada H., Chikamori T., Tsujita K., Teraoka K., Nakajima K., Nakata T., Nakatani S., Nogami A., Node K., Nohara A., Hirayama A., Funabashi N., Miura M., Mochizuki T., Yokoi H., Yoshioka K., Watanabe M., Asanuma T., Ishikawa Y., Ohara T., Kaikita K., Kasai T., Kato E., Kamiyama H., Kawashiri M., Kiso K., Kitagawa K., Kido T., Kinoshita T., Kiriyama T., Kume T., Kurata A., Kurisu S., Kosuge M., Kodani E., Sato A., Shiono Y., Shiomi H., Taki J., Takeuchi M., Tanaka A., Tanaka N., Tanaka R., Nakahashi T., Nakahara T., Nomura A., Hashimoto A., Hayashi K., Higashi M., Hiro T., Fukamachi D., Matsuo H., Matsumoto N., Miyauchi K., Miyagawa M., Yamada Y., Yoshinaga K., Wada H., Watanabe T., Ozaki Y., Kohsaka S., Shimizu W., Yasuda S., Yoshino H.

    Circulation journal : official journal of the Japanese Circulation Society (Circulation journal : official journal of the Japanese Circulation Society)  85 ( 4 ) 402 - 572 2021.03

  • Molecular Imaging of Apoptosis in Atherosclerosis by Targeting Cell Membrane Phospholipid Asymmetry

    Chaudhry F., Kawai H., Johnson K.W., Narula N., Shekhar A., Chaudhry F., Nakahara T., Tanimoto T., Kim D., Adapoe M.K.M.Y., Blankenberg F.G., Mattis J.A., Pak K.Y., Levy P.D., Ozaki Y., Arbustini E., Strauss H.W., Petrov A., Fuster V., Narula J.

    Journal of the American College of Cardiology (Journal of the American College of Cardiology)  76 ( 16 ) 1862 - 1874 2020.10

    ISSN  07351097

     View Summary

    Background: Apoptosis in atherosclerotic lesions contributes to plaque vulnerability by lipid core enlargement and fibrous cap attenuation. Apoptosis is associated with exteriorization of phosphatidylserine (PS) and phosphatidylethanolamine (PE) on the cell membrane. Although PS-avid radiolabeled annexin-V has been employed for molecular imaging of high-risk plaques, PE-targeted imaging in atherosclerosis has not been studied. Objectives: This study sought to evaluate the feasibility of molecular imaging with PE-avid radiolabeled duramycin in experimental atherosclerotic lesions in a rabbit model and compare duramycin targeting with radiolabeled annexin-V. Methods: Of the 27 rabbits, 21 were fed high-cholesterol, high-fat diet for 16 weeks. Nine of the 21 rabbits received Tc-duramycin (test group), 6 received Tc-linear duramycin (duramycin without PE-binding capability, negative radiotracer control group), and 6 received Tc-annexin-V for radionuclide imaging. The remaining normal chow-fed 6 animals (disease control group) received Tc-duramycin. In vivo microSPECT/microCT imaging was performed, and the aortas were explanted for ex vivo imaging and for histological characterization of atherosclerosis. Results: A significantly higher duramycin uptake was observed in the test group compared with that of disease control and negative radiotracer control animals; duramycin uptake was also significantly higher than the annexin-V uptake. Quantitative duramycin uptake, represented as the square root of percent injected dose per cm (√ID/cm) of abdominal aorta was >2-fold higher in atherosclerotic lesions in test group (0.08 ± 0.01%) than in comparable regions of disease control animals (0.039 ± 0.0061%, p = 3.70·10 ). Mean annexin uptake (0.060 ± 0.010%) was significantly lower than duramycin (p = 0.001). Duramycin uptake corresponded to the lesion severity and macrophage burden. The radiation burden to the kidneys was substantially lower with duramycin (0.49% ID/g) than annexin (5.48% ID/g; p = 4.00·10 ). Conclusions: Radiolabeled duramycin localizes in lipid-rich areas with high concentration of apoptotic macrophages in the experimental atherosclerosis model. Duramycin uptake in atherosclerotic lesions was significantly greater than annexin-V uptake and produced significantly lower radiation burden to nontarget organs. 99m 99m 99m 99m –8 –4

  • Development of Upright Computed Tomography with Area Detector for Whole-Body Scans: Phantom Study, Efficacy on Workflow, Effect of Gravity on Human Body, and Potential Clinical Impact

    Jinzaki M., Yamada Y., Nagura T., Nakahara T., Yokoyama Y., Narita K., Ogihara N., Yamada M.

    Investigative Radiology (Investigative Radiology)  55 ( 2 ) 73 - 83 2020.02

    ISSN  00209996

     View Summary

    © Wolters Kluwer Health, Inc. All rights reserved. Objectives Multiple human systems are greatly affected by gravity, and many disease symptoms are altered by posture. However, the overall anatomical structure and pathophysiology of the human body while standing has not been thoroughly analyzed due to the limitations of various upright imaging modalities, such as low spatial resolution, low contrast resolution, limited scan range, or long examination time. Recently, we developed an upright computed tomography (CT), which enables whole-torso cross-sectional scanning with 3-dimensional acquisition within 15 seconds. The purpose of this study was to evaluate the performance, workflow efficacy, effects of gravity on a large circulation system and the pelvic floor, and potential clinical impact of upright CT. Materials and Methods We compared noise characteristics, spatial resolution, and CT numbers in a phantom between supine and upright CT. Thirty-two asymptomatic volunteers (48.4 ± 11.5 years) prospectively underwent both CT examinations with the same scanning protocols on the same day. We conducted a questionnaire survey among these volunteers who underwent the upright CT examination to determine their opinions regarding the stability of using the pole throughout the acquisition (closed question), as well as safety and comfortability throughout each examination (both used 5-point scales). The total access time (sum of entry time and exit time) and gravity effects on a large circulation system and the pelvic floor were evaluated using the Wilcoxon signed-rank test and the Mann-Whitney U test. For a large circulation system, the areas of the vena cava and aorta were evaluated at 3 points (superior vena cava or ascending aorta, at the level of the diaphragm, and inferior vena cava or abdominal aorta). For the pelvic floor, distances were evaluated from the bladder neck to the pubococcygeal line and the anorectal junction to the pubococcygeal line. We also examined the usefulness of the upright CT in patients with functional diseases of spondylolisthesis, pelvic floor prolapse, and inguinal hernia. Results Noise characteristics, spatial resolution, and CT numbers on upright CT were comparable to those of supine CT. In the volunteer study, all volunteers answered yes regarding the stability of using the pole, and most reported feeling safe (average rating of 4.2) and comfortable (average rating of 3.8) throughout the upright CT examination. The total access time for the upright CT was significantly reduced by 56% in comparison with that of supine CT (upright: 41 ± 9 seconds vs supine: 91 ± 15 seconds, P < 0.001). In the upright position, the area of superior vena cava was 80% smaller than that of the supine position (upright: 39.9 ± 17.4 mm2 vs supine: 195.4 ± 52.2 mm2, P < 0.001), the area at the level of the diaphragm was similar (upright: 428.3 ± 87.9 mm2 vs supine: 426.1 ± 82.0 mm2, P = 0.866), and the area of inferior vena cava was 37% larger (upright: 346.6 ± 96.9 mm2 vs supine: 252.5 ± 93.1 mm2, P < 0.001), whereas the areas of aortas did not significantly differ among the 3 levels. The bladder neck and anorectal junction significantly descended (9.4 ± 6.0 mm and 8.0 ± 5.6 mm, respectively, both P < 0.001) in the standing position, relative to their levels in the supine position. This tendency of the bladder neck to descend was more prominent in women than in men (12.2 ± 5.2 mm in women vs 6.7 ± 5.6 mm in men, P = 0.006). In 3 patients, upright CT revealed lumbar foraminal stenosis, bladder prolapse, and inguinal hernia; moreover, it clarified the grade or clinical significance of the disease in a manner that was not apparent on conventional CT. Conclusions Upright CT was comparable to supine CT in physical characteristics, and it significantly reduced the access time for examination. Upright CT was useful in clarifying the effect of gravity on the human body: Gravity differentially affected the volume and shape of the vena cava, depending on body position. The pelvic floor descended significantly in the standing position, compared with its location in the supine position, and the descent of the bladder neck was more prominent in women than in men. Upright CT could potentially aid in objective diagnosis and determination of the grade or clinical significance of common functional diseases.

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Reviews, Commentaries, etc. 【 Display / hide

Presentations 【 Display / hide

  • Temporal relationship between 18F-sodium fluoride uptake and evolution of CT-verified vascular calcification in Abdominal Aorta

    Takehiro Nakahara, Jagat Narula, Josef J. Fox, Masahiro Jinzaki, H. William Strauss,

    2021.03, Oral Presentation(general)

  • Temporal relationship between 18F-sodium fluoride uptake and evolution of CT-verified vascular calcification in Abdominal Aorta

    Takehiro Nakahara, Jagat Narula, Josef J. Fox, Masahiro Jinzaki, H. William Strauss,

    日本循環器学会第85回学術集会, 2021.03, Oral Presentation(general)

  • 陰茎動脈における18F-Fluoride PET画像はErectile Dysfunctionと相関する。

    Takehiro Nakahara, Jagat Narula, Sunil Agarwal, Mohammed M. Chowdhury, Patrick A. Coughlin, Marc Dweck, James Rudd, Masahiro Jinzaki, John Mulhall,, H. William Strauss,

    第60回 日本核医学会学術総会, 2020.11, Oral Presentation(general)

  • 心不全のマルチモダリティイメージング: opening


    日本循環器学会第84回学術集会, 2020.07, Oral Presentation(key)

  • 心不全のマルチモダリティイメージング: Multimodality Imaging in Ischemic Cardiomyopathy


    日本循環器学会第84回学術集会, 2020.07, Oral Presentation(guest/special)

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Research Projects of Competitive Funds, etc. 【 Display / hide

  • A time course of atherosclerosis by PET


    Research grant, Principal Investigator

  • 大動脈瘤の進展予測における核医学の有用性の検討


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 中原 健裕, Grant-in-Aid for Scientific Research (C), Principal Investigator

  • 血管石灰化抑制ホルモンとしてのFGF23の役割の解明


    Research grant, Principal Investigator

  • 心腎連関におけるNotchシグナル及びFGF23の役割の解明


    Research grant, Principal Investigator

Awards 【 Display / hide

  • 2015-2017 SNMMI Wagner-Torizuka fellowship


    Type of Award: Awards of Publisher, Newspaper Company and Foundation

  • 上原記念生命科学財団 ポストドクトラルフェローシップ


    Type of Award: Awards of Publisher, Newspaper Company and Foundation

  • 第16回心世代核医学研究会 最優秀賞


    Type of Award: Awards of National Conference, Council and Symposium

  • Best Young Investigator Award Finalist in the 6th Congress of Asian Society of Cardiovascular Imaging (ASCI). (2012, Bangkok, Thailand)


    Type of Award: Awards of International Conference, Council and Symposium

  • Young Investigator Award Finalist in the SCCT (Society of Cardiovascular Computed Tomography)’s 6th Annual Scientific Meeting. (2011, Denver, CO,USA)


    Type of Award: Awards of International Conference, Council and Symposium

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