LAUSR

BACKGROUND AND AIMS Despite the clinical and genetic significance of macrotrabecular-massive hepatocellular carcinoma (MTM-HCC), its imaging findings have not been described. This study aimed to characterize the imaging findings of MTM-HCC by gadoxetic acid-enhanced magnetic resonance imaging (MRI) and evaluate the diagnostic accuracy and prognostic value of these findings. METHODS We enrolled three independent cohorts from two tertiary care centers. The three cohorts consisted of a total of 476 patients who underwent gadoxetic acid-enhanced MRI and surgical resection for treatment-naïve single HCCs. Independent review of histopathology and MRI by two reviewers was performed for each cohort, and inter-reader agreement was evaluated. Based on the result of MRI review in the training cohort (cohort 1), we developed two diagnostic criteria for MTM-HCC and evaluated their prognostic significance. The diagnostic performance and prognostic significance were validated in two validation cohorts (cohorts 2 and 3). RESULTS We developed two diagnostic MRI criteria (MRIC) for MTM-HCC: MRIC-1, ≥20% arterial phase hypovascular component; MRIC-2, ≥50% hypovascular component and two or more ancillary findings (intratumoral artery, arterial phase peritumoral enhancement, and non-smooth tumor margin). MRIC-1 showed high sensitivity and negative predictive value (88% and 95% in the training cohort, and 88% and 97% in the pooled validation cohorts, respectively), while MRIC-2 demonstrated moderate sensitivity and high specificity (47% and 94% in the training cohort, and 46% and 96% in the pooled validation cohorts, respectively). MRIC-2 was an independent poor prognostic factor for overall survival in both training and pooled validation cohorts. CONCLUSION With gadoxetic acid-enhanced MRI findings including arterial phase hypovascular component, we could stratify the probability of MTM-HCC and non-invasively obtain prognostic information.