"iDoctor – Medical Blog"

OBJECTIVE. The purpose of our study was to evaluate the utility of
single-shot spinecho echo-planar diffusion-weighted imaging (DWI) using a b
value of 400–500 s/mm² for depicting peritoneal tumors.

MATERIALS AND 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/mm²,
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.

CONCLUSION. 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.

This entry was posted on Tuesday, July 21st, 2009 at 3:17 am and is filed under Health news. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.