title: Whole-body MRI including diffusion-weighted imaging compared to CT for staging of malignant melanoma.
abstract: BACKGROUND
  Whole-body (WB) magnetic resonance imaging (MRI), including diffusion-weighted imaging (DWI), has been increasingly used for the detection of metastatic disease.
  
  
  OBJECTIVE
  To assess the value of WB MRI including DWI compared to computed tomography (CT) for staging of malignant melanoma. A second aim was to assess the value of DWI in addition to conventional MR sequences for the detection of lesions.
  
  
  METHODS
  WB MRI with DWI and CT chest, abdomen, and pelvis were performed in 23 patients with histologically confirmed malignant melanoma. CT before and after the MRI examinations and the clinical follow-up was utilized as the standard of reference.
  
  
  RESULTS
  WB MRI and WB DWI detected 345 and 302 lesions, respectively, compared to 397 lesions with CT. The sensitivity of WB MRI and WB DWI varied considerably in different regions of the body. In the lungs, WB MRI and WB DWI showed 63% and 47% true-positive lesions, respectively. WB MRI and WB DWI detected 56 bone lesions in 12 patients compared to 42 lesions in 8 patients with CT. In addition, WB MRI and WB DWI could detect 68 lesions outside the field of view of CT in six patients.
  
  
  CONCLUSIONS
  WB MRI is still not ready to replace CT for staging of malignant melanoma, especially in the thorax region. However, WB MRI is advantageous for detection of bone lesions and lesions outside the investigated volume of the conventional CT. When WB MRI is evaluated, both DWI and conventional MRI sequences must be scrutinized.
authors.affiliation: Department of Radiology, Uppsala University Hospital, Uppsala, Sweden. firas.mosavi@akademiska.se
authors.forename: Firas
authors.initials: F
authors.lastname: Mosavi
authors.forename: Gustav
authors.initials: G
authors.lastname: Ullenhag
authors.forename: Håkan
authors.initials: H
authors.lastname: Ahlström
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult