Extrahepatic abdominal imaging in patients with malignancy: comparison of MR imaging and helical CT in 164 patients

The purpose of this study was to compare the performance of magnetic resonance (MR) imaging using currently available techniques with contrast-enhanced single-phase helical computed tomography (CT) in depicting extrahepatic disease in patients with malignancy. At two institutions, 164 patients with known or suspected malignancy underwent abdominal imaging with contrast-enhanced helical CT and MR imaging. The prospective interpretations of the CT scans and MR examinations were used to assess the sensitivity of each imaging test in detecting benign and malignant extrahepatic disease at 17 anatomic sites. Imaging findings were compared with results of surgery in 57 patients and with the combined results of image-guided biopsy, follow-up cross-sectional imaging studies, other concurrent imaging tests, and clinical follow-up. For the 164 patients, helical CT scans depicted 221 of 316 (70%) sites of proven extrahepatic tumor compared with 288 sites (91%) (P < 0.0001) for MR imaging. For the 57 patients who underwent exploratory laparotomy, helical CT scans depicted 101 of 154 (66%) findings of surgically confirmed extrahepatic tumor compared with MR imaging, which depicted 139 sites (90%) (P < 0.0001). Anatomic sites at which MR imaging showed a significantly greater detection of extrahepatic tumor included the peritoneum, bowel, and vascular and osseous structures. For depiction of benign extrahepatic disease, there was no significant difference between helical CT and MR imaging. MR imaging, using currently available T1-weighted, RARE T2-weighted, and gadolinium-enhanced imaging, is effective in depicting extrahepatic disease in patients with malignancy. Compared with single-phase helical CT scanning, MR imaging shows an advantage in depicting tumor involving the peritoneum, omentum, bowel, and osseous and vascular structures.