KEIO RESEARCHERS INFORMATION SYSTEM

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Research Areas 【 Display / hide 】

• Life Science / Radiological sciences (放射線診断学)

Books 【 Display / hide 】

Books 【 Display / hide 】

• 救急画像診断 一問一答

  八木 文子, 山田 祥岳, 陣崎 雅弘, Ｇａｋｋｅｎ, 2026.04

  Scope: p110-112

• 泌尿器領域画像診断の勘ドコロNEO

  秋田 大宇, 八木 文子, メジカルビュー社, 2021.04,  Page： xv, 295p

  Scope: p4-11

  • CiNii Research

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Physiologic changes in MR findings of an accessory ovary.

  Yagi F, Nakamura K, Jinzaki M

  Japanese journal of radiology  2026.07

  ISSN  1867-1071

  • Access to Document (DOI)

• WHO 2022 Renal Cell Tumor Classification: Imaging Features and Clinical Implications.

  Jinzaki M, Nicola R, Withey SJ, Fütterer JJ, Akita H, Yamamoto A, Ikeda O, Yagi F, Tsuzuki T, Moch H

  Radiographics : a review publication of the Radiological Society of North America, Inc 46 ( 7 ) e250098 2026.07

  ISSN  0271-5333

  　View Summary

  The World Health Organization classification of renal cell tumors was updated to its fifth edition in 2022 and incorporated significant changes with contributions from pathologists and radiologists. In the 2022 updated classification, epithelial renal tumors are now divided into six categories. Four of these six categories represent the major subtypes of renal tumors: clear cell renal tumors, papillary renal tumors, oncocytic and chromophobe renal tumors, and collecting duct tumors. Two additional categories, representing relatively rare renal tumors, termed other renal tumors and molecularly defined renal carcinomas, have been introduced. While neoplasms in the other renal tumors category are classified on the basis of their histopathologic features, similar to the major subtypes, molecularly defined renal carcinomas represent a new category based on molecular characteristics. In recent years, the number of these rare subtypes has increased significantly. Many of these relatively rare renal tumors represent conventional subtypes that have been reclassified or renamed. Notably, papillary renal cell carcinoma (pRCC) type 2 has been reclassified as other renal tumors or molecularly defined renal carcinomas. As a result, many tumors in these two categories demonstrate gradual enhancement, similar to the enhancement of pRCCs. However, one or more of the following features may differ from those of typical pRCCs: patient age, growth pattern, nonenhanced attenuation at CT, degree of enhancement, homogeneity, T2 signal intensity, and presence of metastases. Careful evaluation of these features can raise suspicion for a rare subtype and is essential for guiding urologists in determining the surgical strategies and guiding pathologists in selecting appropriate immunohistopathologic and/or genetic tests for accurate diagnosis. ©RSNA, 2026 Supplemental material is available for this article. See the invited commentary by Davenport and Pedrosa in this issue.

  • Access to Document (DOI)

• Hyperattenuation on non-enhanced CT and T2 hypointensity: an imaging pattern frequently associated with fibrous or smooth muscle-rich abdominal and pelvic lesions.

  Ikeda O, Jinzaki M, Akita H, Yamada Y, Wei C, Yagi F, Tsuzaki J, Tsujioka Y

  Abdominal radiology (New York)  2026.06

  ISSN  2366004X

  　View Summary

  A dual imaging pattern of hyperattenuation on non-enhanced computed tomography and hypointensity on T2-weighted imaging is frequently encountered in various lesions. In the present review, we aimed to explore this imaging combination across a spectrum of abdominal and pelvic lesions to clarify its clinical implications.This pattern is commonly observed in lesions rich in fibrous or smooth muscle components, making it more frequently encountered in benign entities, including fat-poor angiomyolipomas, uterine leiomyomas, and tumors with predominant fibrous stroma. However, similar imaging findings may also be encountered in rare high-cellularity malignancies, selected systemic diseases, and lesions containing melanin, metal deposition, or thyroid tissue. Although not specific to a single disease, this imaging pattern offers valuable diagnostic clues for lesion characterization. When contrast-enhanced imaging is unavailable or contraindicated, combining non-enhanced computed tomography and T2-weighted imaging findings may help narrow the differential diagnosis. Despite its general association with benign lesions, this imaging phenotype requires careful exclusion of important pathologic mimics. Overall, integration with clinical information and other imaging findings remains essential for accurate interpretation.

  • Access to Document (DOI)

• A Case of Testicular Malakoplakia With Markedly High Signal Intensity on Fat‐Suppressed T1‐Weighted Images

  Fumiko Yagi, Hirotaka Akita, Takeo Kosaka, Akihisa Ueno, Teppei Kotera, Masato Kobayashi, Hideaki Mekada, Mototsugu Oya, Masahiro Jinzaki

  IJU Case Reports 9 ( 3 ) e70187 2026.05

  Lead author, Corresponding author, Accepted

  　View Summary

  Introduction: Testicular malakoplakia is a very rare, chronic granulomatous inflammatory condition that frequently resembles testicular malignancy on imaging studies. Here, we report a case of testicular malakoplakia with characteristic magnetic resonance imaging (MRI) findings and present a brief review of the literature. Case Presentation: A man in his 70s presented with left-sided scrotal pain. Ultrasonography revealed a well-defined hypoechoic intratesticular mass without internal vascularity, whereas computed tomography revealed enlargement of the left testis with a relative hyperattenuation area. MRI demonstrated low signal intensity on T2-weighted images, diffusion restriction, and a markedly high signal intensity on fat-suppressed T1-weighted images with contrast enhancement. Based on these findings, a malignant testicular tumor was suspected, and radical orchidectomy was conducted. Histopathological examination confirmed testicular malakoplakia with characteristic Michaelis–Gutmann bodies. Conclusion: This case highlights the importance of recognizing T1 shortening on fat-suppressed T1-weighted MRI as a potential imaging modality for malakoplakia.

  • Access to Document (DOI)

• 特集 画像診断レポート学−私の書き方− 【骨盤部】 骨盤部領域レポート記載について−自分の考えを伝える気持ちを大切に−

  八木 文子, 秋田 大宇, 藤原 広和, 陣崎 雅弘

  臨床画像 (メジカルビュー社)  42 ( 13 ) 98 - 105 2026.04

  ISSN  09111069

  • Access to Document (DOI)
  • CiNii Research

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

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

• 従来型CTと立位CTを用いた臥位と立位での尾骨の動きの三次元的評価

  Yagi, Fumiko

  (慶應義塾大学大学院医学研究科)  2023

• 従来型CTと立位CTを用いた臥位と立位での尾骨の動きの三次元的評価

  Yagi, Fumiko

  (慶應義塾大学大学院医学研究科)  2023

• 従来型CTと立位CTを用いた臥位と立位での尾骨の動きの三次元的評価

  Yagi, Fumiko

  (慶應義塾大学大学院医学研究科)  2023

Reviews, Commentaries, etc. 【 Display / hide 】

Reviews, Commentaries, etc. 【 Display / hide 】

• 悪性リンパ腫との鑑別に苦慮した高齢発症の精巣セミノーマの1例

  宮崎 彩花, 八木 文子, 秋田 大宇, 陣崎 雅弘, 松本 一宏, 大家 基嗣, 大喜多 肇, 上野 彰久

  Japanese Journal of Radiology ((公社)日本医学放射線学会)  44 ( Suppl. ) 28 - 28 2026.02

  ISSN  1867-1071

• 続General Radiology診断演習　大切なものは目にみえない

  八木 文子, 秋田 大宇, 陣崎 雅弘

  画像診断 ((株)Gakken)  45 ( 13 ) 1302 - 1305 2025.10

  ISSN  0285-0524

  　View Summary

  ＜文献概要＞40歳代,女性.LDH高値,骨盤内腫瘤

  • Access to Document (DOI)
  • CiNii Research

• 【続General Radiology診断演習】大切なものは目にみえない

  八木 文子, 秋田 大宇, 陣崎 雅弘

  画像診断 45 ( 13 ) 1302 - 1305 2025.10

• Correction to: A case of immunoglobulin G4-related disease with a urethral lesion diagnosed by radiological imaging before biopsy (Abdominal Radiology, (2024), 50, 4, (1672-1678), 10.1007/s00261-024-04594-0)

  Yagi F., Akita H., Matsumoto K., Arai E., Meng W., Furuya K., Senda S., Oya M., Jinzaki M.

  Abdominal Radiology 50 ( 10 ) 5066 - 5067 2025.10

  ISSN  2366004X

  　View Summary

  The original version of this article unfortunately contained a mistake. The “Abstract” and “Keywords” sections were missing in the published version. However, now it is corrected. We present a 50-year-old female with IgG4-related disease (IgG4-RD) of the urethra. She had been diagnosed with IgG4-RD involving the pancreas, lacrimal glands, salivary glands, kidneys, and right breast 5 years earlier, which had remitted after steroid treatment. In recent months, she had experienced urinary incontinence. Her local physician noted a urethral stricture. Magnetic resonance imaging (MRI) showed a lesion surrounding the urethra, with a slightly high signal intensity on T2-weighted and short-term inversion recovery images, and a mildly high signal intensity on diffusion-weighted images. Accordingly, IgG4-RD involving the urethra was suggested. Her serum IgG4 level was slightly elevated at 127 mg/dL, which is below the normal upper limit of 135 mg/dL. A transurethral biopsy revealed significant lymphocytic and IgG4-positive plasma cell infiltrates (50–80/high-power field), fibrosis, and obstructive phlebitis. Thus, IgG4-RD of the urethra was confirmed. A systematic search including CT and MRI did not reveal any new gross lesions. Steroid therapy improved her symptoms within a few days. Follow-up MRI revealed shrinking of the urethral lesion and lower signal intensity on T2-weighted images. IgG4-RD with urethral lesions is extremely rare. No cases of diagnosis of IgG4-RD urethral lesions based on MRI findings before biopsy have been reported to date. When a middle-aged woman presents with uniform circumferential urethral lesions, IgG4-RD should be considered in the differential diagnosis. Here, we report detailed imaging findings and radiological differential diagnoses, and discuss relevant literature. Keywords Urinary incontinence, Circumferential lesion, Dysuria, IgG4-related disease, Periurethral lesion, Urethra The original article has been corrected.

  • Access to Document (DOI)

• 【IgG4関連疾患とその鑑別 -IgG4-related or not? That is the question-】腎泌尿器領域のIgG4関連疾患とその鑑別

  八木 文子, 秋田 大宇, 陣崎 雅弘

  画像診断 ((株)Gakken)  45 ( 12 ) 1157 - 1167 2025.09

  ISSN  0285-0524

  　View Summary

  ＜文献概要＞●腎皮質・辺縁優位に両側性の小さな結節が多発性に認められた場合,IgG4関連疾患(IgG4-RD)の尿細管間質性腎炎の可能性がある.その画像所見は多彩であり,単発性腫瘤の形態を呈した場合には,乏血性腎細胞癌との鑑別が困難である.●IgG4-RDの上部尿路病変では,尿路上皮癌と比較し,両側性,尿路病変が長い,壁外への進展,境界不明瞭,漸増性の造影効果,大動脈浸潤,大動脈周囲/仙骨前/骨盤壁領域の脂肪織濃度上昇などの尿路外所見を呈する.●中高年女性で均一な全周性の尿道病変をみた際には,鑑別にIgG4-RDを考慮する.●IgG4-RDの既往がある,あるいは疑われる症例において,下部尿路症状や逆V字型FDG集積を来した場合には,IgG4-RDによる前立腺病変の可能性も考慮する.●IgG4-RDの陰嚢内病変は,精巣上体炎や線維性偽腫瘍として発症する場合がある.

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Presentations 【 Display / hide 】

Presentations 【 Display / hide 】

• 腎泌尿器領域のIgG4関連疾患とその鑑別疾患

  八木文子

  第18回西日本GUR研究会, 

  2026.05

• 症例検討

  八木文子, 千代田 達幸, 上野 彰久, 山田 祥岳, 陣崎 雅弘

  信濃町画像診断セミナー, 

  2026.05

• 副卵巣の一例

  八木文子, 中村加奈子, 陣崎雅弘

  第93回東京泌尿生殖器放射線勉強会, 

  2026.05

• IgG4-related disease in the urinary tract; imaging findings and mimickers

  Fumiko Yagi, Hirotaka Akita, Yoshitake Yamada, Masahiro Jinzaki

  第85回日本医学放射線学会総会, 

  2026.04

• Upright CT Imaging for the Musculoskeletal System

  Yoshitake Yamada, Minoru Yamada, Yoichi Yokoyama, Taiki Nozaki, Orito Ikeda, Fumiko Yagi, Yuki Iwaita, Takeo Nagura, Masaya Nakamura, Masahiro Jinzaki

  第85回日本医学放射線学会総会, 

  2026.04

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Awards 【 Display / hide 】

Awards 【 Display / hide 】

• 成績優秀者 第1位

  2026.05, 第18回西日本GUR研究会

• 第31回「画像診断」MVP 賞

  八木 文子, 2026.03, 「画像診断」編集委員会, 腎泌尿器領域のIgG4関連疾患とその鑑別

• レントゲンカンファレンス優秀解答者

  八木文子, 2026.02, 第45回日本画像医学会学術集会

• Certificate of Merit

  Fumiko Yagi, Hirotaka Akita, Yoshitake Yamada, Masahiro Jinzaki, 2025.12, Radiological Society of North America (RSNA) 2025, IgG4-related disease in the urinary tract; imaging findings and mimickers

• Identified for RadioGraphics

  Fumiko Yagi, Hirotaka Akita, Yoshitake Yamada, Masahiro Jinzaki, 2025.12, Radiological Society of North America (RSNA) 2025, IgG4-related disease in the urinary tract; imaging findings and mimickers

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Academic Activities 【 Display / hide 】

Academic Activities 【 Display / hide 】

• Radiology Case Reports

  2026.05

  -

  Present

• Case Reports in Radiology

  2026.04

  -

  Present

• Quantitative Imaging in Medicine and Surgery

  2026.02

  -

  Present

• Case reports in obstetrics and gynecology

  2026.01

  -

  Present

• Magnetic Resonance in Medical Sciences

  2026.01

  -

  Present

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