MR imaging differentiation of fibrosis versus recurrent colorectal carcinoma in the pelvis

The authors have compared the ability of 1.5-T MR imaging and CT to distinguish recurrent colorectal carcinoma from fibrosis in the pelvis. A retrospective review of 15 consecutive patients with suspected recurrence was performed. Signal intensity measurements were obtained at sites of previous surgery and were compared with measurements of fat and muscle on T1- and moderately and heavily T2-weighted sequences. The differences between tumor and fibrosis were found to be statistically significant on long repetition time, long echo time images (P < .002). MR imaging can accurately differentiate recurrent colorectal carcinoma from fibrosis in the pelvis and appears to be the modality of choice for this problem