title: Is (18)F-FDG PET useful in predicting the WHO grade of malignancy in thymic epithelial tumors? A meta-analysis.
abstract: OBJECTIVE
  To perform a systematic review and meta-analysis of published data on the role of fluorine-18-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) in predicting the WHO grade of malignancy in thymic epithelial tumors (TETs).
  
  
  METHODS
  A comprehensive literature search of studies published up to March 2014 was performed. Data on maximum standardized uptake value (SUVmax) in patients with low-risk thymomas (A, AB, B1), high-risk thymomas (B2, B3) and thymic carcinomas (C) according to the WHO classification were collected when reported by the retrieved articles. The comparison of mean SUVmax between low-risk thymomas, high-risk thymomas and thymic carcinomas was expressed as weighted mean difference (WMD) and a pooled WMD was calculated including 95% confidence interval (95%CI).
  
  
  RESULTS
  Eleven studies were selected for the meta-analysis. The pooled WMD of SUVmax between high-risk and low-risk thymomas was 1.2 (95%CI: 0.4-2.0). The pooled WMD of SUVmax between thymic carcinomas and low-risk thymomas was 4.8 (95%CI: 3.4-6.1). Finally, the pooled WMD of SUVmax between thymic carcinomas and high-risk thymomas was 3.5 (95%CI: 2.7-4.3).
  
  
  CONCLUSIONS
  (18)F-FDG PET may predict the WHO grade of malignancy in TETs. In particular, we demonstrated a statistically significant difference of SUVmax between the different TETs (low-grade thymomas, high-grade thymomas and thymic carcinomas).
authors.affiliation: Department of Nuclear Medicine and PET/CT Center, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Treglia
authors.affiliation: Nuclear Medicine Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Sadeghi
authors.affiliation: Department of Nuclear Medicine and PET/CT Center, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Giovanella
authors.affiliation: Unit of Thoracic Surgery, San Giovanni Hospital, Bellinzona, Switzerland.
authors.forename: Stefano
authors.initials: S
authors.lastname: Cafarotti
authors.affiliation: Unit of Thoracic Surgery, University of Turin, Turin, Italy.
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Filosso
authors.affiliation: Unit of Thoracic Surgery, IRCCS-Arcispedale Santa Maria Nuova, Reggio Emilia, Italy. Electronic address: filippo_lococo@yahoo.it.
authors.forename: Filippo
authors.initials: F
authors.lastname: Lococo
mesh_terms: D019788:Fluorodeoxyglucose F18; D006801:Humans; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D009375:Neoplasms, Glandular and Epithelial / Q000000981:diagnostic imaging* / Q000473:pathology*; D049268:Positron-Emission Tomography; D013945:Thymoma / Q000000981:diagnostic imaging / Q000473:pathology; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: FDG; Meta-analysis; PET/CT; Positron emission tomography; Thymic; Thymoma