title: Detectability of liver metastases in malignant melanoma: prospective comparison of magnetic resonance imaging and positron emission tomography.
abstract: OBJECTIVE
  We evaluated the diagnostic accuracy of magnetic resonance imaging (MRI) and positron emission tomography (PET) for detection of liver metastases in malignant melanoma.
  
  
  METHODS
  Thirty-five patients with 39 combined unenhanced MRI and fluorine-18 deoxyglucose (F-18 FDG) PET scans were prospectively studied. In discordant imaging findings final diagnosis was proven by clinical follow-up >6 months and demonstration of progressive liver metastases by at least one imaging method. Sensitivities and specificities were compared and the influence of lesion size and melanin content on diagnostic accuracy was determined.
  
  
  RESULTS
  MRI and PET were concordantly negative for presence and number of liver metastases in 28 patients and positive in four patients. PET and MRI were false positive in one patient each. In one patient MRI showed a single metastases not seen by PET and in one patient MRI demonstrated more metastases at the first examination. In follow-up investigations MRI revealed more metastases than PET in both patients. The sensitivities for lesion detection were 47% (16/34) for PET and 100% for MRI. Lesion detectability by PET was related to lesion size (P < 0.0001) but not to melanin content.
  
  
  CONCLUSIONS
  MRI is more sensitive in the detection of liver metastases in patients with malignant melanoma. Small lesions are easily missed by PET, while melanin content does not influence detectability by PET.
authors.affiliation: Department of Diagnostic Radiology, University Hospital Freiburg, Freiburg 79106, Germany. gha@mrs1@ukl.uni-freiburg.de
authors.forename: Nadir
authors.initials: N
authors.lastname: Ghanem
authors.forename: Carsten
authors.initials: C
authors.lastname: Altehoefer
authors.forename: Stefan
authors.initials: S
authors.lastname: Högerle
authors.forename: Egbert
authors.initials: E
authors.lastname: Nitzsche
authors.forename: Christian
authors.initials: C
authors.lastname: Lohrmann
authors.forename: Oliver
authors.initials: O
authors.lastname: Schäfer
authors.forename: Elmar
authors.initials: E
authors.lastname: Kotter
authors.forename: Mathias
authors.initials: M
authors.lastname: Langer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008543:Melanins / Q000378:metabolism; D008545:Melanoma / Q000175:diagnosis* / Q000556:secondary*; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D008543:Melanins; D019788:Fluorodeoxyglucose F18