Diagnostic value in magnetic resonance imaging of intrapelvic recurrence of rectal carcinoma

Findings of magnetic resonance imaging (MRI) and computed tomography (CT) were compared, with the purpose of examining the usefulness of MRI in the diagnosis of local recurrence of rectal carcinoma, especially the differentiation between recurrent tumors and scar tissues. The subjects were 18 patients with suspected recurrent carcinoma. In 9 patients with recurrent carcinoma, T2-weighted imaging revealed higher signal intensity in recurrent carcinoma than the muscle; in 5 of 6 patients with scar tissue, it revealed lower signal intensity in the scar tissue than the muscle. This made it possible to differentiate recurrent carcinoma from scar tissue. In the remaining three patients, seminal vesicles and enlarged uterine cervix were seen as high signal intensities on T2-weighted images, leading to misinterpretation of recurrent tumors. X-ray CT, on the other hand, provided appearance of homogeneous soft tissue mass in all cases, thus making it difficult to differentiate recurrent carcinoma and scar tissue. T2-weighted images helped in diagnosing local recurrence of rectal carcinoma. (Namekawa, K.)