Prospective comparative study of magnetic resonance imaging versus transrectal ultrasound for preoperative staging and follow-up of rectal cancer. Preliminary report.

The efficiency of magnetic resonance imaging (MRI) and that of transrectal ultrasound (TRUS) were compared in preoperative staging of 15 patients with rectal cancer and in postoperative follow-up of 12 patients. Thirteen of the 15 patients evaluated for preoperative staging were operated on. Preoperative staging and pathologic finding were identical in 11 patients (84.6 percent) examined by TRUS and in 10 patients (76.9 percent) examined by MRI. Recurrent cancer was detected in 3 of 12 patients in the follow-up group. MRI was able to diagnose correctly 10 of 12 patients (83.2 percent), one patient was misdiagnosed, and in one patient the MRI could not distinguish between fibrous tissue and recurrent cancer. TRUS diagnosed correctly only 5 of 12 patients (41.6 percent). One was falsely diagnosed, and, in 6 patients (50 percent), this examination could not differentiate between fibrous tissue and recurrent tumor. According to our results, both MRI and TRUS have a place in the preoperative staging of patients with rectal cancer. The main differences between the two methods were in the differential diagnoses of fibrous tissue and recurrent cancer. MRI being more specific in detection of recurrence.