Gadoxetic acid-enhanced MRI for diagnosis of hepatocellular carcinoma in patients with chronic liver disease: can hypointensity on the late portal venous phase be used as an alternative to washout?

Purpose: To investigate the added value of considering hypointensity on late portal venous phase (LPVP) images as washout for diagnosis of hepatocellular carcinoma (HCC) using gadoxetic acid-enhanced MRI (Gd-EOB-MRI) in patients with chronic liver disease (CLD). Methods: This retrospective study comprised 97 patients at high risk for HCC who underwent Gd-EOB-MRI including unenhanced, multi-arterial phase, conventional portal venous phase (CPVP, 60 s), and LPVP (mean, 99.9 ± 9.1 s; range, 90–119 s) images. A total of 115 hepatic lesions were identified by histopathological or clinical diagnosis. Three independent radiologists assessed the MRI images by consensus. Diagnosis of HCC was made using criteria of arterial hyperenhancement and hypointensity relative to the surrounding liver parenchyma (1) on CPVP or (2) on CPVP and/or LPVP images. The generalized estimating equation was used to compare diagnostic performance for HCC between Criterion 1 and 2. Results: In 82 HCCs, the frequency of hypointensity differed significantly between the CPVP and LPVP images (64.6% [53/82] vs. 84.1% [69/82], P < 0.001). Among 33 non-HCCs, two cHCC-CCs showed additional hypointensity on LPVP than CPVP images (33.3% [11/33] vs. 39.4% [13/33], P = 0.500). Criterion 2 provided significantly greater sensitivity for diagnosing HCC than Criterion 1 (54.9% [45/82] vs. 74.4% [61/82], P < 0.001), with relatively little reduction in specificity (90.9% [30/33] vs. 84.8% [28/33], P = 0.145). Conclusion: Additional use of LPVP hypointensity as washout could significantly improve sensitivity for HCC diagnosis when utilizing Gd-EOB-MRI in patients with CLD, without a significant decrease in specificity.