title: Diffusion-weighted MRI of peritoneal tumors: comparison with conventional MRI and surgical and histopathologic findings--a feasibility study.
abstract: OBJECTIVE
  The purpose of our study was to evaluate the utility of single-shot spin-echo echo-planar diffusion-weighted imaging (DWI) using a b value of 400-500 s/mm(2) for depicting peritoneal tumors.
  
  
  METHODS
  Thirty-four consecutive oncology patients underwent preoperative abdominal and pelvic MRI for tumor staging. MRI included breath-hold DWI with a b value of 400-500 s/mm(2), T1-weighted spoiled gradient-echo, T2-weighted fast spin-echo, and 0- and 5-minute delayed gadolinium-enhanced imaging. At three separate sessions, two observers independently reviewed images for peritoneal tumors at 16 anatomic sites. First DWI alone was reviewed, followed by conventional MRI alone, and then conventional MRI, including DWI, was reviewed. Results of laparotomy and histopathologic evaluation were compared with MRI results. Sensitivity, specificity, and accuracy were calculated for DWI, conventional MRI, and combined DWI and conventional MRI for peritoneal tumor depiction.
  
  
  RESULTS
  Two-hundred fifty-five sites of peritoneal tumor were proven by surgical and histopathologic findings. The combination of DWI and conventional MRI was most sensitive and accurate for peritoneal tumors, depicting 230 and 214 tumor sites for the two observers (sensitivity, 0.90, 0.84; and accuracy, 0.91, 0.88) compared with DWI alone, which depicted 182 and 182 tumor sites with sensitivity (0.71, 0.71; and accuracy, 0.81, 0.81), and conventional MRI alone, which depicted 185 and 132 tumor sites (sensitivity, 0.73, 0.52; and accuracy, 0.81, 0.72). Peritoneal tumor showed restricted diffusion on DWI and ascites was of low signal intensity, increasing tumor conspicuity.
  
  
  CONCLUSIONS
  Adding DWI to routine MRI improves the sensitivity and specificity for depicting peritoneal metastases. Breath-hold DWI is now routinely used in all oncology patients referred for abdominal MRI at our institution.
authors.affiliation: Sharp and Children's MRI Center, 7901 Frost St., San Diego, CA 92123, USA. rlow52@yahoo.com
authors.forename: Russell N
authors.initials: RN
authors.lastname: Low
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Sebrechts
authors.forename: Robert M
authors.initials: RM
authors.lastname: Barone
authors.forename: Wayne
authors.initials: W
authors.lastname: Muller
mesh_terms: D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000473:pathology; D010534:Peritoneal Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000556:secondary* / Q000601:surgery; D011553:Pseudomyxoma Peritonei / Q000175:diagnosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000473:pathology