title: (18)F-FDG PET for the evaluation of thymic epithelial tumors: Correlation with the World Health Organization classification in addition to dual-time-point imaging.
abstract: OBJECTIVE
  Our aim was to determine dual-phase (18)F-FDG PET imaging features for various subtypes of thymic epithelial tumors based on the World Health Organization classification.
  
  
  METHODS
  Forty-six patients with histologically verified thymic epithelial tumors [23 with low-risk tumors (4 with type A, 16 with AB, and 3 with B1) and 23 with high-risk tumors (7 with B2, 5 with B3, and 11 with thymic carcinoma] were enrolled in this study. All patients were injected with (18)F-FDG.; after 1 h, they underwent scanning; after 3 h, 23 patients underwent an additional scanning. The maximum standard uptake value (SUV(max)) and the retention index (RI%) of the lesions were determined.
  
  
  RESULTS
  The early and delayed SUV(max) values in the patients with high-risk tumors [early SUV(max) (mean: 6.0) and delayed SUV(max) (mean: 7.4)] were both significantly larger than those in patients with low-risk tumors [early SUV(max) (mean: 3.2) and delayed SUV(max) (mean: 3.4)] (P < 0.05). Early SUV(max) values of greater than 7.1 differentiated thymic carcinomas from other types of tumors. For the histological differentiation between high-risk tumors and low-risk tumors, an early SUV(max) value of 4.5 was used as the cutoff. The sensitivity, specificity, and accuracy were 78.3, 91.3, and 84.8%, respectively.
  
  
  CONCLUSIONS
  High SUV values (early SUV > 4.5) suggest the presence of high-risk tumors. A very high SUV value (early SUV > 7.1) is useful for the differentiation of thymic carcinomas from other types of tumors. The delayed SUV values were higher than the early SUV values in all types of tumors.
authors.affiliation: Department of Nuclear Medicine and Tracer Kinetics, 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: Mitsuaki
authors.initials: M
authors.lastname: Tatsumi
authors.forename: Naoki
authors.initials: N
authors.lastname: Ikeda
authors.forename: Meinoshin
authors.initials: M
authors.lastname: Okumura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shiono
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Inoue
authors.forename: Ichiro
authors.initials: I
authors.lastname: Higuchi
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Aozasa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Johkoh
authors.forename: Hironobu
authors.initials: H
authors.lastname: Nakamura
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000145:classification* / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D013953:Thymus Neoplasms / Q000145:classification* / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D013997:Time Factors; D014944:World Health Organization
chemical_list: D019788:Fluorodeoxyglucose F18