title: FDG PET-CT aids in the preoperative assessment of patients with newly diagnosed thymic epithelial malignancies.
abstract: BACKGROUND
  Advanced thymoma (stage III and IV) is difficult to detect by computed tomography (CT), yet it is important to distinguish between early (stage I and II) and advanced disease before surgery, as patients with locally advanced tumors require neoadjuvant chemotherapy to enable effective resection. This study assessed whether the amount of fluorodeoxyglucose (FDG) uptake can predict advanced thymoma and whether it can separate thymoma from thymic cancer.
  
  
  METHODS
  We retrospectively reviewed FDG positron emission tomography (PET)-CT scans of 51 consecutive newly diagnosed patients with thymic epithelial malignancy. PET-CT findings documented focal FDG activity: SUVmax, SUVmean, SUVpeak, and total body volumetric standardized uptake value (SUV) measurements. These were correlated with Masaoka-Koga staging and World Health Organization classification. Wilcoxon ranked sum tests were used to assess association between SUV and pathological stage, cancer type, and classification.
  
  
  RESULTS
  Among the study patients, 37 had thymoma, 12 thymic carcinoma, and 2 thymic carcinoid. Higher focal FDG uptake was seen in patients with type B3 thymoma than in those with type A, AB, B1, or B2 thymoma (p < 0.006). FDG uptake was higher in patients with thymic carcinoma or carcinoid than in patients with thymoma (p < 0.0003), with more variable associations with volumetric SUV measurements. There was no significant association observed between higher focal FDG uptake and advanced-stage disease in thymoma patients (p > 0.09), although greater FDG-avid tumor volume was significantly associated with advanced disease (p < 0.03).
  
  
  CONCLUSIONS
  Focal FDG uptake cannot predict advanced thymoma but is helpful in distinguishing thymoma from thymic carcinoma, or the more aggressive thymoma, type B3.
authors: Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors: Marcelo F K
authors: MF
authors: Benveniste
authors: Cesar A
authors: CA
authors: Moran
authors: Osama
authors: O
authors: Mawlawi
authors: Patricia S
authors: PS
authors: Fox
authors: Stephen G
authors: SG
authors: Swisher
authors: Reginald F
authors: RF
authors: Munden
authors: Edith M
authors: EM
authors: Marom
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002276:Carcinoid Tumor; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009375:Neoplasms, Glandular and Epithelial / Q000175:diagnosis* / Q000601:surgery; D049268:Positron-Emission Tomography; D011300:Preoperative Care; D011379:Prognosis; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D013945:Thymoma / Q000175:diagnosis* / Q000601:surgery; D013953:Thymus Neoplasms / Q000175:diagnosis* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18