title: MR imaging of thymic epithelial tumors: correlation with World Health Organization classification.
abstract: OBJECTIVE
  The aim of this study was to determine magnetic resonance imaging (MRI) features of various subtypes of thymic epithelial tumors based on the World Health Organization classification.
  
  
  METHODS
  The study included 64 patients with histologically proven thymic epithelial tumors. Two observers evaluated the MRI findings in terms of tumor size, contour, lobulation, shape, homogeneity, the presence of intratumor high- and low-signal foci, enhancement degree and pattern, the presence of capsule and septum, and associated mediastinal lymphadenopathy and pleural effusion.
  
  
  RESULTS
  Type A tumors were more likely to have a smooth contour, round shape, distinct capsule, and smaller size compared to any other type of thymic epithelial tumor. Thymic carcinomas demonstrated a higher prevalence of low-signal foci within the mass on T2-weighted images and mediastinal lymphadenopathy than any other types. The frequency of heterogeneous intensity on T2-weighted images increased from type A tumors to thymic carcinomas.
  
  
  CONCLUSIONS
  The presence of a smooth contour, round shape, and capsule is highly suggestive of a type A tumor. Foci of low signal intensity in the mass on T2-weighted images and mediastinal lymphadenopathy are highly suggestive of thymic carcinomas.
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. ainoue@radiol.med.osaka-u.ac.jp
authors.forename: Atsuo
authors.initials: A
authors.lastname: Inoue
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Tomiyama
authors.forename: Kiminori
authors.initials: K
authors.lastname: Fujimoto
authors.forename: Junko
authors.initials: J
authors.lastname: Sadohara
authors.forename: Itsuko
authors.initials: I
authors.lastname: Nakamichi
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tomita
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Aozasa
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Tsubamoto
authors.forename: Sachiko
authors.initials: S
authors.lastname: Murai
authors.forename: Javzandulam
authors.initials: J
authors.lastname: Natsag
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Sumikawa
authors.forename: Naoki
authors.initials: N
authors.lastname: Mihara
authors.forename: Osamu
authors.initials: O
authors.lastname: Honda
authors.forename: Seiki
authors.initials: S
authors.lastname: Hamada
authors.forename: Takeshi
authors.initials: T
authors.lastname: Johkoh
authors.forename: Hironobu
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013945:Thymoma / Q000145:classification* / Q000175:diagnosis* / Q000473:pathology; D013953:Thymus Neoplasms / Q000145:classification* / Q000175:diagnosis* / Q000473:pathology; D014944:World Health Organization