MR imaging of thymic epithelial tumors: correlation with World Health Organization classification.
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.
Inoue
Atsuo
A
Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. ainoue@radiol.med.osaka-u.ac.jp
Tomiyama
Noriyuki
N
Fujimoto
Kiminori
K
Sadohara
Junko
J
Nakamichi
Itsuko
I
Tomita
Yasuhiko
Y
Aozasa
Katsuyuki
K
Tsubamoto
Mitsuko
M
Murai
Sachiko
S
Natsag
Javzandulam
J
Sumikawa
Hiromitsu
H
Mihara
Naoki
N
Honda
Osamu
O
Hamada
Seiki
S
Johkoh
Takeshi
T
Nakamura
Hironobu
H
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