259

IMSUT Hospital

Department of Radiology
放射線科

Associate Professor
Hiroyuki Akai, M.D., D.M.Sc.
Senior Assistant Professor Toshihiro Furuta, M.D., D.M.Sc.
Assistant Professor
Haruomi Yamaguchi, M.D., D.M.Sc.
Project Assistant Professor Shimpei Kato, M.D., D.M.Sc.

准教授
講 師助 教
特任助教

博士（医学）
博士（医学）
博士（医学）
博士（医学）

赤古山加井田口藤宏
寿晴伸行宏
臣平

Department of Radiological Technology
放射線部

Associate Professor
Hiroyuki Akai, M.D., D.M.Sc.
Head Radiologic Technologist Kenji Ino, RT

准教授
放射線技師長博士（医学）

赤井井野宏賢行二The Department of Radiology undertakes radiology service at IMSUT hospital. Our
expertise includes general diagnostic radiology, neuroradiology, clinical nuclear
medicine, and radiation therapy. Board-certified radiologists at the Department ofRadiology conduct all examinations of CT, MRI, and nuclear medicine. Radiologicalreports are made by the radiologists. In addition, several clinical studies are being
conducted in collaboration with other departments or institutions. We also
investigate the technical aspects of molecular imaging with intact small animals for
its application to preclinical studies using an optical imaging system and MRI.
The Department of Radiological Technology constitutes the hospital radiology
service together with the Department of Radiology. Plain radiography, dual-energy
X-ray absorptiometry, and barium studies are also available at the Department ofRadiological Technology, other than CT, MRI, and radioisotope examinations. Morethan 10,000 patients visit our department every year. Radiologic technologists atthe department make an effort to provide high-quality medical images in daily
practice as well as to reasonably reduce radiation exposure of a patient during theexamination.

Feasibility study of direct CT lymphangiography
in mice: comparison with interstitial CT/MR lymphangiography.
Sugawara H, Furuta T, Sumiyoshi A1, Iiyama M1,Kamitani M, Suzuki A2, Murakami A2, Abe O3, Aoki
I1, Akai H.

Functional and Molecular Imaging Group, Department of Molecular Imaging and Theranostics,
Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, 2 Department of Diagnostic Radiology, Kanto Rosai
Hospital, 3 Department of Radiology, Graduate
School of Medicine, University of Tokyo1260
In the present study, we aimed to establish a CT
lymphangiography method in mice via direct lymph
node puncture. We injected healthy mice (n = 8) with
50 µl of water-soluble iodine contrast agent (iomeprol; iodine concentration, 350 mg/mL) subcutaneously into the left-rear foot pad (interstitial injection)and 20 µl of the same contrast agent directly into thepopliteal lymph node (direct puncture) 2 days later.
Additionally, we performed interstitial MR lymphangiography on eight mice as a control group. We
calculated the contrast ratio for each lymph node andvisually assessed the depiction of lymph nodes andlymphatic vessels on a three-point scale. As a result,the contrast ratios of 2-min post-injection images ofsacral and lumbar-aortic lymph nodes were 20.7 ±16.6 (average ± standard deviation) and 17.1 ± 12.0 in
the direct puncture group, which were significantly
higher than those detected in the CT or MR interstitial
lymphangiography groups (average, 1.8-3.6; p =0.008-0.019). The visual assessment scores for sacral
lymph nodes, lumbar-aortic lymph nodes, and cisterna chyli were significantly better in the direct puncture group than in the CT interstitial injection group(p = 0.036, 0.009 and 0.001, respectively). The lymphatic vessels between these structures were significantly better scored in direct puncture group than in
the CT or MR interstitial lymphangiography groups
at 2 min after injection (all p ≤ 0.05). To sum up, in CT
lymphangiography in mice, the direct lymph nodepuncture provides a better delineation of the lymphatic pathways than the CT/MR interstitial injection
method, which we believe that direct CT lymphangiography will be the first choice for the evaluation oflymphatic pathways in mice.

Yamaguchi H, Ichikawa T4, Morisaka H5, Akai H,Izuka K6, Ueno T6, Abe O3, Tsushima Y4.
4
Diagnostic Radiology and Nuclear Medicine Department, Gunma University Graduate School ofMedicine, 5 Department of Radiology, University of
Yamanashi, 6 Department of Gastroenterology, Isesazaki Municipal HospitalThis study aims to assess the diagnostic value ofvirtual monochromatic image (VMI) at low keV energy for early detection of small hepatocellular carcinoma (HCC) in hepatic arterial phase compared withlow-tube voltage (80 kVp) CT generated from dual-energy CT (DE-CT). A total of 107 patients with 114
hypervascular HCCs (≤2 cm) underwent DE-CT, 140
kVp, blended 120 kVp, and 80 kVp images were generated, as well as 40 and 50 keV. CT numbers of HCCs
and the standard deviation as image noise on psoas
muscle were measured. The contrast-to-noise ratios(CNR) of HCC were compared among all techniques.
Overall image quality and sensitivity for detecting
HCC hypervascularity were qualitatively assessed bythree readers. The mean CT numbers, CNR, and image noise were highest at 40 keV followed by 50 keV,
80 kVp, blended 120 kVp, and 140 kVp. Significant differences were found in all evaluating endpoints except for mean image noise of 50 keV and 80 kVp. Image quality of 40 keV was the lowest, but still it wasconsidered acceptable for diagnostic purposes. The
mean sensitivity for detecting lesion hypervascularity
with 40 keV (92%) and 50 keV (84%) was higher thanthose with 80 kVp (56%). Low keV energy images
were superior to 80 kVp in detecting hypervascularization of early HCC.

Early detection of hypervascularization in hepatocellular carcinoma (≤ 2 cm) on hepatic arterial
phase with virtual monochromatic imaging: Comparison with low-tube voltage CT.

Publications
1.		Tajima T, Akai H, Yasaka K, Kunimatsu A, Yamashita Y, Akahane M, Yoshioka N, Abe O, Ohtomo K,Kiryu S. Usefulness of deep learning-based noise
reduction for 1.5 T MRI brain images. Clin Radiol.
78:e13-e21 2023.
2.		Akai H, Yasaka K, Sugawara H, Tajima T, Kamitani M, Furuta T, Akahane M, Yoshioka N, Ohtomo K, Abe O, Kiryu S Acceleration of knee magnetic resonance imaging using a combination ofcompressed sensing and commercially available
deep learning reconstruction: a preliminary study.
BMC Med Imaging. 23:5 2023.
3.		Sugawara H, Yatabe Y, Watanabe H, Akai H, AbeO, Watanabe SI, Kusumoto M. Radiological precursor lesions of lung squamous cell carcinoma:

Early progression patterns and divergent volume
doubling time between hilar and peripheral zones.
Lung Cancer. 176:31-37 2023.
4.		Ohgami Y, Kotani Y, Yoshida N, Akai H, Kunimatsu A, Kiryu S, Inoue Y. The contralateral effects ofanticipated stimuli on brain activity measured byERP and fMRI. Psychophysiology. 60:e14189 2023.
5.		Kiryu S, Akai H, Yasaka K, Tajima T, Kunimatsu
A, Yoshioka N, Akahane M, Abe O, Ohtomo K.
Clinical Impact of Deep Learning Reconstructionin MRI. Radiographics. 43:e220133 2023.
6.		Akai H, Yasaka K, Sugawara H, Tajima T, Akahane
M, Yoshioka N, Ohtomo K, Abe O, Kiryu S. Commercially Available Deep-learning-reconstructionof MR Imaging of the Knee at 1.5T Has Higher Im-261
age Quality Than Conventionally-reconstructed
Imaging at 3T: A Normal Volunteer Study. MagnReson Med Sci. 22:353-360 2023.
7.		Sugawara H, Furuta T, Sumiyoshi A, Iiyama M,Kamitani M, Suzuki A, Murakami A, Abe O, Aoki
I, Akai H. Feasibility study of direct CT lymphangiography in mice: comparison with interstitial CT/
MR lymphangiography. Eur Radiol. 33:5028-5036
2023.
8.		Hosoi R, Yasaka K, Mizuki M, Yamaguchi H, Miyo
R, Hamada A, Abe O. Deep learning reconstruction with single-energy metal artifact reduction inpelvic computed tomography for patients withmetal hip prostheses. Jpn J Radiol. 41:863-871
2023.
9.		Yamaguchi H, Ichikawa T, Morisaka H, Akai H,Izuka K, Ueno T, Abe O, Tsushima Y. Early detec-tion of hypervascularization in hepatocellular carcinoma (≤ 2 cm) on hepatic arterial phase with virtual monochromatic imaging: Comparison with
low-tube voltage CT. Medicine (Baltimore).
102:e34774 2023.
10.	Tajima T, Akai H, Yasaka K, Kunimatsu A, Yoshioka N, Akahane M, Ohtomo K, Abe O, Kiryu S.
Comparison of 1.5 T and 3 T magnetic resonanceangiography for detecting cerebral aneurysms using deep learning-based computer-assisted detection software. Neuroradiology. 65:1473-1482 2023.
11.	Sugawara H, Kikkawa N, Ito K, Watanabe H, Kaku
S, Akai H, Abe O, Watanabe S, Yatabe Y, Kusumoto M. Is 18F-fluorodeoxyglucose PET recommended for small lung nodules? CT findings of 18F-fluorodeoxyglucose non-avid lung cancer. Br J Radiol2023 Dec 13. [Epub ahead of print]