Detection of hepatic lesions in candidates for surgery: comparison of ferumoxides-enhanced MR imaging and dual-phase helical CT.

OBJECTIVE: The purpose of this study was to compare the use of phased array MR imaging of the liver at 1.5 T with and without ferumoxides with dual-phase helical CT for the detection of hepatic lesions in candidates for hepatic surgery. SUBJECTS AND METHODS: Patients with known or suspected hepatic lesions who were eligible for surgery underwent dual-phase helical CT at 20 and 70 sec after the start of contrast material injection and phased array MR imaging using fast spin-echo T2-weighted imaging and gradient-echo T1-weighted imaging before and after ferumoxides infusion of 0.56 mg of iron per kilogram of body weight. Three observers who were unaware of the surgical findings separately reviewed the CT scans and unenhanced and enhanced MR images of 24 patients who completed the protocol. The observers' findings were compared with results obtained at surgery using intraoperative sonography and having histopathologic confirmation. Statistical analysis was performed using a segment-by-segment analysis.
RESULTS: Eighty-two lesions were found at surgery. The sensitivity of CT, unenhanced MR imaging, and enhanced MR imaging for blinded observers was 60.4%, 62.0%, and 68.2%, respectively. The specificity was 89.2%, 81.9%, and 81.6%, respectively. Five lesions in three patients were not detected preoperatively using any of the techniques. MR imaging found additional lesions not detected on CT in four patients; CT detected one additional lesion not seen on MR imaging.
CONCLUSION: Ferumoxides-enhanced MR imaging of the liver shows a trend toward increased sensitivity compared with dual-phase helical CT. Specificity of helical CT was superior to that of enhanced MR imaging for most observers.