title: Utility of 18FDG-PET for differentiating the grade of malignancy in thymic epithelial tumors.
abstract: OBJECTIVE
  The objective of this study was to assess the value of (18)F-FDG PET in thymic epithelial tumors according to the WHO histologic classification and to evaluate its potential for differentiating the grade of malignancy in thymic epithelial tumors.
  
  
  METHODS
  Thirty-six patients with a thymic epithelial tumor who underwent (18)F-FDG PET examination before treatment were enrolled in the present study. The T/M ratio, which is the ratio of the peak standardized uptake value (SUV) of the tumor to the mean SUV of mediastinum, was compared in subgroups of a simplified WHO histological classification; low-risk thymoma (Types A, AB and B1), high-risk thymoma (Types B2 and B3), and thymic carcinoma.
  
  
  RESULTS
  Tumors included 15 low-risk thymomas, 10 high-risk thymomas and 11 thymic carcinomas. Upon visual inspection, all tumors showed (18)F-FDG accumulation and the mean T/M ratio in these three subgroups was 2.64, 4.29 and 8.90, respectively. The differences between the three subgroups were statistically significant (low-risk vs. high-risk: p=0.01, high-risk vs. thymic carcinoma: p=0.01).
  
  
  CONCLUSIONS
  A significant relationship was seen between (18)F-FDG PET accumulation and histologic subtype in thymic epithelial tumors when they were classified into three groups. PET may be useful for predicting the grade of malignancy in thymic epithelial tumors.
authors.affiliation: Division of Endoscopy and Diagnostic Radiology, Shizuoka Cancer Center, Nagaizumi, Shizuoka, Japan. m.endo@scchr.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Endo
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Ohde
authors.forename: Takehiro
authors.initials: T
authors.lastname: Okumura
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Kondo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Igawa
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Asuka
authors.initials: A
authors.lastname: Tsuya
authors.forename: Haruyasu
authors.initials: H
authors.lastname: Murakami
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Takahashi
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Ichiro
authors.initials: I
authors.lastname: Ito
authors.forename: Toru
authors.initials: T
authors.lastname: Kameya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013945:Thymoma / Q000000981:diagnostic imaging* / Q000473:pathology; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18