title: PET/CT in malignant melanoma: contrast-enhanced CT versus plain low-dose CT.
abstract: OBJECTIVE
  The aim of this study was to evaluate the diagnostic value of contrast-enhanced CT (CECT) versus non-enhanced low-dose CT (NECT) in the staging of advanced malignant melanoma with (18)F-fluordeoxyglucose (FDG) positron emission tomography (PET)/CT.
  
  
  METHODS
  In total, 50 (18)F-FDG PET/CT examinations were performed in 50 patients with metastasized melanoma. For attenuation correction, whole-body NECT was performed followed by diagnostic CECT with contrast agent. For the whole-body PET, (18)F-FDG was applied. Criteria for evaluation were signs of vital tumour tissue (extent of lesions, contrast enhancement, maximum standardized uptake value >2.5). Findings suspicious for melanoma were considered lesions. NECT, CECT and (18)F-FDG PET were evaluated separately, followed by combined analysis of PET/NECT and PET/CECT. Findings were verified histologically and/or by follow-up (>6 months).
  
  
  RESULTS
  Overall, 232 lesions were analysed, and 151 proved to be metastases. The sensitivity of NECT, CECT, PET, PET/NECT and PET/CECT was 62, 85, 90, 97 and 100%, and specificity was 52, 63, 88, 93 and 93%, respectively. Compared to CECT, NECT obtained additional false-negative results: lymph node (n = 19) and liver/spleen metastases (n = 9). Misinterpreted physiological structures mainly caused additional false-positive findings (n = 17). In combined analysis of PET/NECT, six false-positive [other tumours (n = 2), inflammatory lymph nodes (n = 2), inflammatory lung lesion (n = 1), blood vessel (n = 1)] and five false-negative findings [liver (n = 3), spleen (n = 1), lymph node metastases (n = 1)] remained. On PET/CECT, six false-positive [inflammatory lymph nodes (n = 3), other tumours (n = 2), inflammatory lung lesion (n = 1)] and no false-negative findings occurred. However, additional false findings on PET/NECT (6 of 232) did not change staging compared to PET/CECT.
  
  
  CONCLUSIONS
  Our results indicate that it is justified to perform PET/NECT instead of PET/CECT for melanoma staging.
authors.affiliation: Department of Nuclear Medicine, LMU, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Pfluger
authors.forename: Henriette Ingrid
authors.initials: HI
authors.lastname: Melzer
authors.forename: Vera
authors.initials: V
authors.lastname: Schneider
authors.forename: Christian
authors.initials: C
authors.lastname: La Fougere
authors.forename: Eva
authors.initials: E
authors.lastname: Coppenrath
authors.forename: Carola
authors.initials: C
authors.lastname: Berking
authors.forename: Peter
authors.initials: P
authors.lastname: Bartenstein
authors.forename: Mayo
authors.initials: M
authors.lastname: Weiss
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000473:pathology; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011829:Radiation Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D019788:Fluorodeoxyglucose F18