Abstract
Purpose
To compare the performance of dynamic gadolinium‐enhanced and ferumoxides‐enhanced MRI in the detection and characterization of hepatic lesions, on 1.5‐T and 0.2‐T magnets
Materials and Methods
In 41 patients (23 men, 18 women), 52 hepatic MR examinations were performed and retrospectively analyzed; 39 and 13 examinations were performed on 1.5‐T and 0.2‐T magnets, respectively. A total of 33 of 41 patients had known malignancies, and 31 of 33 patients had biopsy of at least one lesion. First, a combination of unenhanced T2‐weighted sequences and gradient‐echo T1‐weighted sequences were performed. Then, dynamic gadolinium‐enhanced (0.1 mmol/kg) T1 GRE sequences were obtained, followed by intravenous drip infusion of ferumoxides (10 μmol/kg). The T2‐weighted sequences were then repeated. The unenhanced and gadolinium‐enhanced images (the Gd set) were reviewed separately from the unenhanced and ferumoxides‐enhanced images (the ferumoxides set) by two abdominal imagers. The reviewers were blinded to clinical history and reviewed the individual studies in each set randomly. Each detected lesion was scored on a five‐point scale for characterization scores: nonsolid (1 or 2), indeterminate (3), or solid (4 or 5). A consensus review was then performed correlating all available pathology, imaging, clinical findings, and follow‐up to act as a gold standard. Receiver‐operating‐characteristic (ROC) curves were generated and both area‐under‐the‐curve (Az values) and sensitivity values were calculated. Significance of Az and sensitivity differences was assessed using standard Z‐test and chi‐square.
Results
Of 270 lesions detected by consensus, 211 were on 1.5‐T and 59 were on 0.2‐T scanners. The accuracy (Az values) of lesion detection overall, of both readers, was greater for the ferumoxides set than for the Gd set (reader 1: 0.95 vs. 0.89 (P < 0.05); reader 2: 0.91 vs. 0.78 (P < 0.05)). Az values for both readers were greater on the ferumoxides set for both the 1.5‐T scans and the 0.2‐T scans. Out of 270 lesions detected, 231 were characterized by consensus review as solid (185) or nonsolid (46). There was a significant improvement in lesion characterization for both readers on the GD set compared with the ferumoxides set on both high and low field scanners (Az reader 1: 0.99 vs. 0.96 (P < 0.05); Az reader 2: 0.99 vs. 0.95 (P < 0.05)), respectively.
Conclusion
At both 1.5‐T and 0.2‐T, ferumoxides‐enhanced sequences were better for lesion detection, while gadolinium‐enhanced sequences were better for lesion characterization, respectively. J. Magn. Reson. Imaging 2004;20:640–647. © 2004 Wiley‐Liss, Inc.