Radiologic-Pathologic Correlation of Hepatobiliary Phase Hypointense Nodules without Arterial Phase Hyperenhancement at Gadoxetic Acid-enhanced MRI: A Multicenter Study

Abstract

Background: Hepatobiliary phase (HBP) hypointense nodules without arterial phase hyper enhancement (APHE) at gadoxetic acid enhanced MRI may indicate hepatocellular carcinoma (HCC) or nonmalignant cirrhosis-associated nodules. Purpose: To assess the distribution of pathologic diagnoses of HBP hypointense nodules without APHE at gadoxetic acid-enhanced MRI and to evaluate clinical and imaging features in differentiating their histologic grades. Materials and Methods: This retrospective multicenter study included pathologic analysis-confirmed HBP hypointense nodules without APHE (<= 30 mm) in patients with chronic liver disease or cirrhosis screened between January 2008 and June 2016. Central pathologic review by 10 pathologists determined final histologic grades as progressed HCC, early HCC, high-grade dysplastic nodule (DN), and low-grade DN or regenerative nodule. Gadoxetic acid-enhanced MRI features were analyzed by three radiologists. Multivariable logistic regression analyses with elastic net regularization were performed to identify clinical and imaging features for differentiating histologic grades. Results: There were 298 patients (mean age, 59 years +/- 10; 226 men) with 334 nodules evaluated, and progressed HCCs were diagnosedin 44.0% (147 of 334), early HCCs in 20.4% (68 of 334), high-grade DNs in 27.5% (92 of 334), and low-grade DNs orregenerative nodules in 8.1% (27 of 334). Serum alpha-fetoprotein level 100 ng/mL or greater (odds ratio, 2.7; P =.01) and MRI features including well-defined margin (odds ratio, 5.5; P =.003), hypointensity at precontrast T1-weighted imaging (odds ratio, 3.2;P <.001), intermediate hyperintensity at T2-weighted imaging (odds ratio, 3.4; P <.001), and restricted diffusion (odds ratio, 1.9; P =.04) were independent predictors for progressed HCC at multivariable analysis. Conclusion: In patients at high risk for hepatocellular carcinoma (HCC), hepatobiliary phase hypointense nodules without arterial phase hyperenhancement at gadoxetic acid-enhanced MRI corresponded mainly to progressed HCCs, early HCCs, and high-grade dysplasticnodules. High alpha-fetoprotein level and some imaging features at MRI helped to differentiate progressed HCC from lower grade nodules. (C) RSNA, 2020