title: Can dual-time-point 18F-FDG PET/CT differentiate malignant salivary gland tumors from benign tumors?
abstract: OBJECTIVE
  The purpose of this study is to evaluate the usefulness of dual-time-point 18F-FDG PET/CT for discriminating between benign and malignant salivary gland tumors.
  
  
  METHODS
  Dual-time-point FDG PET/CT images of 40 salivary gland tumors (20 benign and 20 malignant) were evaluated retrospectively. The maximum standardized uptake values (SUVmax) in the early and delayed phases and the retention index of each tumor were calculated and compared between benign and malignant tumors by the Mann-Whitney U test. Receiver operating characteristic (ROC) analysis was used to determine the diagnostic accuracy for malignant salivary gland tumors. The correlation between the delayed SUVmax and retention index was analyzed by calculation of the Spearman correlation coefficient.
  
  
  RESULTS
  There were no significant differences in the mean early phase SUVmax or mean delayed phase SUVmax between benign and malignant tumors. The mean (±SD) retention index of the malignant tumors was significantly higher than that of the benign tumors (20.1%±10.2% vs 8.5%±12.3%; p=0.006). When the cutoff value of retention index (15.0%) was used, the sensitivity, specificity, and accuracy each was determined to be 75.0%. ROC analysis did not reveal a significant difference in the diagnostic accuracy between the delayed phase SUVmax and retention index (p=0.139). A significant correlation between the delayed phase SUVmax and retention index was observed for the benign salivary gland tumors (r=0.839; p<0.001).
  
  
  CONCLUSIONS
  Dual-time-point FDG PET/CT is not useful for discriminating between benign and malignant salivary gland tumors, because benign tumors also show high FDG uptake, which increases in the delayed phase.
authors: Department of Diagnostic Radiology and Oncology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan. trihmrad@tmd.ac.jp
authors: Akira
authors: A
authors: Toriihara
authors: Shin
authors: S
authors: Nakamura
authors: Kazunori
authors: K
authors: Kubota
authors: Tomoko
authors: T
authors: Makino
authors: Kiyoshi
authors: K
authors: Okochi
authors: Hitoshi
authors: H
authors: Shibuya
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D011859:Radiography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012468:Salivary Gland Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18