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 tomography (CT) and magnetic resonance (MR) imaging in the staging of colorectal carcinoma. MATERIALS AND METHODS: CT and MR studies were independently interpreted in a group of 478 patients with colorectal carcinoma in a study conducted from 1989 to 1993. The accuracy of each modality was assessed in a subset of 363 patients with primary tumors with respect to staging of local extent of tumor, status of local-regional lymph nodes, and the presence of liver metastases. RESULTS: In the staging of local extent of tumor, CT is more accurate than MR imaging, particularly in the definition of penetration of the muscularis propria 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 evaluation of liver metastases; lower sensitivities (62% and 70%, respectively) than specificities (97% and 94%, respectively) were demonstrated for both modalities. CONCLUSION: CT was more accurate than MR imaging in detection and characterization of transmural penetration of rectal tumors. Recent technologic advances in MR imaging may affect these results.