To prospectively compare gadoxetate disodium-enhanced magnetic resonance (MR) imaging with multiphasic 64-section multidetector computed tomography (CT) in the detection of hepatocellular carcinoma (HCC) in patients with cirrhosis. Institutional review board approval and informed patient consent were obtained for this prospective study. Fifty-eight patients (39 men, 19 women; mean age, 63 years; age range, 35-84 years) underwent gadoxetate disodium-enhanced MR imaging and multiphasic 64-section multidetector CT. The imaging examinations were performed within 30 days of each other. The two sets of images were qualitatively analyzed in random order by three independent readers in a blinded and retrospective fashion. Using strict diagnostic criteria for HCC, readers classified all detected lesions with use of a four-point confidence scale. The reference standard was a combination of pathologic proof, conclusive imaging findings, and substantial tumor growth at follow-up CT or MR imaging (range of follow-up, 90-370 days). The diagnostic accuracy, sensitivity, and positive predictive value were compared between the two image sets. Interreader variability was assessed. The accuracy of each imaging method was determined by using an adjusted modified chi(2) test. Eighty-seven HCCs (mean size +/- standard deviation, 1.8 cm +/- 1.5; range, 0.3-7.0 cm) were confirmed in 42 of the 58 patients. Regardless of lesion size, the average diagnostic accuracy and sensitivity for all readers were significantly greater with gadoxetate disodium-enhanced MR imaging (average diagnostic accuracy: 0.88, 95% confidence interval [CI]: 0.80, 0.97; average sensitivity: 0.85, 95% CI: 0.74, 0.96) than with multidetector CT (average diagnostic accuracy: 0.74, 95% CI: 0.65, 0.82; average sensitivity: 0.69, 95% CI: 0.59, 0.79) (P < .001 for each). No significant difference in positive predictive value was observed between the two image sets for each reader. Interreader agreement was good to excellent. Compared with multiphasic 64-section multidetector CT, gadoxetate disodium-enhanced MR imaging yields significantly higher diagnostic accuracy and sensitivity in the detection of HCC in patients with cirrhosis. (c) RSNA, 2010.