Comparison of gadobenate dimeglumine-enhanced dynamic MRI and 16-MDCT for the detection of hepatocellular carcinoma

OBJECTIVE. The objective of our study was to compare the diagnostic performance of gadobenate dimeglumine-enhanced MRI with that of 16-MDCT for the detection of hepatocellular carcinoma using receiver operating characteristic (ROC) curve analysis. MATERIALS AND METHODS. Thirty-one patients with 53 hepatocellular carcinomas underwent gadobenate dimeglumine-enhanced dynamic MRI and multiphasic CT using 16-MDCT within a mean interval of 5 days (range, 3-9 days). The dynamic MRI examination was performed using 3D fat-saturated volumetric interpolated imaging and sensitivity encoding on a 1.5-T unit. Both dynamic MRI and multiphasic MDCT included dual arterial phase images. Three observers independently interpreted the CT and MR images in random order, separately, and without patient identifiers. The diagnostic accuracy of each technique was evaluated using the alternative-free response ROC method. The sensitivity and positive predictive values were also calculated. RESULTS. The sensitivities of gadobenate dimeglumine-enhanced MRI for all observers were significantly higher than those of MDCT for all the lesions and for lesions 1.0 cm or smaller (p < 0.05); however, for lesions larger than 1.0 cm, the sensitivities of the two imaging techniques were similar. The mean area under the ROC curve (A) of gadobenate dimeglumine-enhanced MRI (0.87 +/- 0.03 [SD]) was higher than that of MDCT (0.83 +/- 0.04), but no significant difference was found between them (p = 0.31). The number of false-positive findings on dynamic MRI was slightly higher than on MDCT, but no significant difference in the positive predictive value between the two imaging techniques was detected (observer 1, p 0.06; observer 2, p = 0.13; observer 3, p = 1.00). CONCLUSION. Gadobenate dimeglumine-enhanced MRI has a higher sensitivity for small hepatocellular carcinomas (<= 1 cm) but a higher false-positive rate due to nonspecific enhancement of benign lesions, such as arterioportal shunt, leading to no significant difference of overall accuracy when compared with MDCT.