Subtraction Images of Gadoxetic Acid-Enhanced MRI: Effect on the Diagnostic Performance for Focal Hepatic Lesions in Patients at Risk for Hepatocellular Carcinoma.

Abstract

The purpose of this study is to evaluate the effect of subtraction images of gadoxetic acid-enhanced MRI on the image interpretation of focal hepatic lesions in patients at risk for hepatocellular carcinoma (HCC). We retrospectively analyzed 255 malignant nodules from 233 patients with chronic hepatitis or liver cirrhosis (187 men and 46 women; mean age, 55.2 years) who underwent preoperative gadoxetic acid-enhanced MRI and surgical resection. We compared the detection rate of arterial hypervascularity on visual assessment with that of subtraction images. Subgroup analysis was performed according to the pathologic profile of the lesion (HCC vs non-HCC), the lesion size (≤ 3 vs > 3 cm), and the MRI technique (1.5 vs 3 T). We assessed the effect of subtraction images in diagnosing HCC according to the American Association for the Study of Liver Diseases guidelines compared with that of visual assessment. After excluding six patients whose images were not of nondiagnostic quality, 249 nodules (215 HCCs, 27 cholangiocarcinomas, and seven combined HCC and cholangiocarcinomas) from 227 patients were analyzed. Subtraction images more sensitively detected the arterial hypervascularity of all of the hepatic lesions than did visual assessment (sensitivity, 89.2% vs 72.4%; p < 0.001). In all of the subgroup analyses, the same tendency was observed (p = 0.001-0.145). Compared with visual assessment only, arterial hypervascularity determined by both subtraction images and the visual enhancement patterns increased sensitivity from 76.5% to 87.5% (p < 0.001) in diagnosing HCCs, with a minimal decrease in specificity from 80.9% to 78.1% (p = 0.332). Adding subtraction images with consideration of visual enhancement patterns can enhance the sensitivity in diagnosing HCC by enhancing the detection of arterial hypervascularity.