Non-Hypervascular Hypointense Nodules at Gadoxetic Acid MRI: Hepatocellular Carcinoma Risk Assessment with Emphasis on the Role of Diffusion-Weighted Imaging.

Abstract

In cirrhotic patients, the characterization of hypovascular nodules, hypointense on hepatobiliary phase gadoxetic acid disodium-enhanced magnetic resonance images (Gd-EOB-DTPA-enhanced MRI), is essential to look for the proper approach strategy. Our objective was to evaluate the imaging features and risk assessment of hypovascular nodules, hypointense on Gd-EOB-DTPA-enhanced MRI, focusing on the diagnostic value of diffusion-weighted imaging (DWI). This prospective study includes 35 patients with 50 hypovascular hypointense nodules. Signal intensity on T2-weighted images and DWI, vascular pattern on dynamic contrast-enhanced MRI and on hepatobiliary phase, and volume doubling time were analyzed for each nodule as well as patient's clinical features. Univariate and multivariate analyses were made to determine the variables associated with the development of hypervascular pattern. On 24months follow-up period, 40% of the hypointense nodules (mean size 14mm±6.1) became hypervascular hepatocellular carcinoma (HCC) with 6 and 12months cumulative risk of 45 and 55%. Nine/12 (75%, mean size 15.50mm±7.2) that appeared hyperintense in DWI at first exam show malignant transformation (p value=0.007). Univariate and multivariate analyses identified hyperintensity at initial DWI (OR 6.49; 95% CI 1.28-32.80; p value=0.009) and size ≥10mm (OR 6.22; 95% CI 1.57-24.63; p value=0.024) as independent factors with the development of HCC. In conclusion, hypovascular lesions ≥10mm and those hyperintense in DWI were associated with progression to hypervascular HCC. A close follow-up or histological characterization is recommended to improve patients outcome and to develop effective treatment.