Gadoxetic Acid–Enhanced Hepatobiliary Phase MRI and High-b-Value Diffusion-Weighted Imaging to Distinguish Well-Differentiated Hepatocellular Carcinomas From Benign Nodules in Patients With Chronic Liver Disease

Abstract

The purpose of this article is to evaluate the value of gadoxetic acid-enhanced hepatobiliary phase imaging and high-b-value diffusion-weighted imaging (DWI) for distinguishing well-differentiated hepatocellular carcinomas (HCCs) from benign hepatocellular nodules in patients with chronic liver disease using 3-T MRI. Forty-five patients with 46 well-differentiated HCCs (mean, 2.3 cm) and 21 patients with 24 benign hepatocellular nodules (five large regenerative nodules and 19 dysplastic nodules; mean, 1.8 cm) were included in this study. Diagnosis of well-differentiated HCCs and benign hepatocellular nodules was made histopathologically by percutaneous biopsy (n = 12 and n = 11, respectively) or surgical resection (n = 34 and n = 13, respectively). Gadoxetic acid-enhanced MRI was performed for all patients, and DWI (b values of 0 and 800 s/mm(2)) was performed for 31 well-differentiated HCCs and 11 benign hepatocellular nodules. Two radiologists performed a consensus review of the MRI scans for signal intensity compared with that of the surrounding liver parenchyma on hepatobiliary phase images and DWI (b value, 800 s/mm(2)) for qualitative analysis. The contrast-to-noise ratio (CNR) and relative contrast enhancement of lesions on hepatobiliary phase images and the apparent diffusion coefficient (ADC) values were assessed for quantitative analysis. In the qualitative analysis, 39 well-differentiated HCCs (85%) and 14 benign hepatocellular nodules (58%) were hypointense on hepatobiliary phase images, and seven well-differentiated HCCs (15%) and 10 benign hepatocellular nodules (42%) were iso- or hyperintense (p = 0.04). Twenty-five well-differentiated HCCs (81%) and three benign hepatocellular nodules (27%) were hyperintense on DWI, with b value of 800 s/mm(2), and six well-differentiated HCCs (19%) and eight benign hepatocellular nodules (73%) were iso- or hypointense (p = 0.01). When lesion hypointensity on hepatobiliary phase images or hyperintensity on DWI were considered signs of HCC in cirrhotic liver, our results yielded sensitivities of 85% and 81% and specificities of 42% and 73%, respectively. In the quantitative analysis, the mean (± SD) relative contrast enhancement ratio of the well-differentiated HCCs (0.76 ± 2.30) was significantly higher than that of benign hepatocellular nodules (0.25 ± 0.97) (p = 0.02). The lesion-to-liver CNRs and the mean ADC values were not significantly different between the two groups (p > 0.05). Hypointensity on gadoxetic acid-enhanced hepatobiliary phase images and hyperintensity on high-b-value DWI to surrounding liver parenchyma suggest well-differentiated HCCs rather than benign hepatocellular nodules in chronic liver disease.