Evaluation of hepatic metastases from colorectal carcinoma with MR-superparamagnetic iron oxide

The purpose of this study was to compare the results obtained with superparamagnetic iron oxide-enhanced and unenhanced Magnetic Resonance at 1.5 T with that of spiral-computed tomography (CT) in order to select those patients suitable for liver resection; the intraoperative US (IOUS) comprised the gold standard. Thirty five candidates for liver resection with known colorectal neoplasm were studied; 26 patients underwent Surgery, one patient underwent RF ablation and 8 of them were submitted to follow-up. MR examination was performed using a 1.5 T superconductive instrument, CT examination was performed on a Somatom-Plus (Siemens) scanner. Dimensions and number of the lesions were defined in all patients as well as the sensitivity of spiral CT and MR imaging, using either the plain technique or after Ferumoxides c.m.. In those patients submitted to surgery, results have been Correlated to those of IOUS. From 26 patients, a total of 48 lesions were removed surgically. With CT, 34 lesions with 3 false positive cases were detected; 32 with plain MR imaging, while MR imaging with Ferumoxides detected 41 lesions. In the patients not submitted to surgery, MR iron-oxide imaging identified 15 lesions. while both plain MR imaging and CT showed 8 lesions. The smallest lesion was 6 mm. as shown by MR imaging with Ferumoxides. In the cases submitted to surgery, the CT sensitivity was 71%, plain MR imaging 66% and MR imaging with Ferumoxides 85%. In our experience, Ferumoxides-enhanced MR imaging of the liver shows increased sensitivity compared to plain and spiral-CT in the evaluation of hepatic metastases. We think that MR superparamagnetic iron oxide should be used in all patients selected for liver resection.