CT AND MR-IMAGING IN THE STAGING OF COLORECTAL-CARCINOMA - REPORT OF THE RADIOLOGY DIAGNOSTIC ONCOLOGY GROUP-II

PURPOSE: To prospectively evaluate the relative accuracy of computed t omography (CT) and magnetic resonance (MR) imaging in the staging of c olorectal carcinoma. MATERIALS AND METHODS: CT and MR studies were ind ependently interpreted in a group of 478 patients with colorectal carc inoma in a study conducted from 1989 to 1993. The accuracy of each mod ality was assessed in a subset of 365 patients with primary tumors wit h respect to staging of local extent of tumor, status of local-regiona l lymph nodes, and the presence of liver metastases. RESULTS: In the s taging of local extent of tumor, CT is more accurate than MR imaging, particularly in the definition of penetration of the muscularis propri a by rectal cancer (74% vs 58%). Accuracies of CT and MR imaging were equivalent in depiction of transmural extent in colon cancers. CT and MR imaging exhibited accuracies of 62% and 64% in assessment of lymph node involvement with sensitivities of 48% and 22%, respectively. The accuracy of MR imaging and of CT (85% for each) are better for evaluat ion of liver metastases; lower sensitivities (62% and 70%, respectivel y) than specificities (97% and 94%, respectively) were demonstrated fo r both modalities. CONCLUSION: CT was more accurate than MR imaging in detection and characterization of transmural penetration of rectal tu mors. Recent technologic advances in MR imaging may affect these resul ts.