Liver Imaging Reporting and Data System:: Substantial Discordance Between CT and MR for Imaging Classification of Hepatic Nodules

Abstract

The Liver Imaging Reporting and Data System (LI-RADS) is a newly developed nomogram for standardizing the performance and interpretation of liver imaging. However, it is unclear which imaging technique is optimal to exactly define LI-RADS scale. This study aims to determine the concordance of computed tomography (CT) and magnetic resonance imaging (MRI) for the classification of hepatic nodules (HNs) using a LI-RADS scoring system. Major imaging features (arterial hyper-enhancement, washout, pseudo-capsule, diameter, and tumor embolus) on CT versus MRI for 118 HNs in 84 patients with diffuse liver disease were rated independently using LI-RADS by two groups of readers. Inter-reader agreement (IRA) and intraclass agreement was determined by Fleiss and Cohen's kappa (κ). Logistic regression for correlated data was used to compare diagnostic ability. IRA was perfect for determination of nodule size and tumor embolus (κ = 0.94-0.98). IRA was moderate to substantial for determination of arterial hyper-enhancement, washout, and pseudo-capsule (κ = 0.54-0.72). Intraclass agreement between CT and MRI was substantial for determination of washout (0.632 [95% CI: 0.494, 0.771]) and pseudo-capsule (0.670 [95% CI: 0.494, 0.847]), and fair for arterial hyper-enhancement (0.203 [95% CI: 0.051, 0.354]). CT against MR produced false-negative findings of arterial hyper-enhancement by 57.1%, washout by 21.2%, and pseudo-capsule by 42.9%; and underestimated LI-RADS score by 16.9% for LR 3, 37.3% for LR 4, and 8.5% for LR 5. CT produced significantly lower accuracy (54.3% vs 67.8%, P < 0.001) and sensitivity (31.6% vs 71.1%, P < 0.001) than MRI in the prediction of malignancy. There are substantial discordance between CT and MR for stratification of HNs using LI-RADS. MRI could be better than CT in optimizing the performance of LI-RADS.