title: Does 18F-FDG PET/CT play a role in the differential diagnosis of parotid masses.
abstract: OBJECTIVE
  The aim of the present study was to assess the accuracy of an hybrid PET/CT scanner in the evaluation of newly diagnosed parotid masses, comparing the results with those reported in the literature with using PET scanners only.
  
  
  METHODS
  The potential role of 18F-FDG PET/CT in distinguishing benign from malignant parotid masses in 14 consecutive patients was investigated. All patients were preoperatively evaluated by means of ultrasound (US), US-guided fine needle aspiration (FNA) cytology, computed tomography (CT) scan, magnetic resonance imaging (MRI) and 18F-FDG PET/CT. For To interpreting FDG PET findings, the right to left parotid (R/L) SUV max ratio was calculated in a group of 54 patients without evidence of parotideal disease (mean+/-SD = 1+/-0.2; range = 0.8-1.2); considering the R/L SUV max ratio, focal or diffuse uptakes <0.8 or >1.2 were considered as potentially pathological.
  
  
  RESULTS
  Imaging data were compared with surgical and histopathological findings. At FDG PET/CT, 9 false positive cases were found (8 Warthin's tumours, 1 pleomorphic adenoma), 1 false negative (acinar cell carcinoma), 4 true negative (1 Warthin's tumour, 1 pleomorphic adenoma, 1 lymph epithelial cyst, 1 parotid inflammation) whereas there was no case of true positive. The global accuracy of FGD PET/CT was rather low = at 29%.
  
  
  CONCLUSIONS
  In agreement with other preliminary reports in which the FDG PET without CT fusion imaging was used, in our experience 18F-FDG PET/CT did not prove to play a significant role in differential diagnosis (benign vs malignant) of parotid masses. Further studies collecting larger groups of patients are needed to further elucidate this observation.
authors.affiliation: Department of Nuclear Medicine, S. Maria della Misericordia Hospital, Rovigo, Italy. domenico.rubello@libero.it
authors.forename: D
authors.initials: D
authors.lastname: Rubello
authors.forename: C
authors.initials: C
authors.lastname: Nanni
authors.forename: P
authors.initials: P
authors.lastname: Castellucci
authors.forename: L
authors.initials: L
authors.lastname: Rampin
authors.forename: M
authors.initials: M
authors.lastname: Farsad
authors.forename: R
authors.initials: R
authors.lastname: Franchi
authors.forename: G
authors.initials: G
authors.lastname: Mariani
authors.forename: G
authors.initials: G
authors.lastname: Menaldo
authors.forename: S
authors.initials: S
authors.lastname: Fanti
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D010307:Parotid Neoplasms / Q000175:diagnosis* / Q000473:pathology; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18