Fat in mass in primary liver lesions: are usual MRI diagnostic criteria of both malignant and benign liver lesions still applicable?

Abstract

To evaluate the accuracy of the usual MRI diagnostic patterns of primary liver lesions applied to the diagnosis of pathologically proven fat-containing liver lesions. This monocentric IRB approved retrospective study included all patients with pathologically proven focal liver lesions and documented intra-tumoral fat on pathology and who underwent preoperative liver MRI for characterization. Both liver morphology and usual lesion MRI features were analyzed and their distribution correlated to the final pathological result (Khi-2 or Fisher exact tests, Student t-test or Mann-Whitney U test, as appropriate). The Sensitivity (Se) and Specificity (Sp) of MRI patterns known to be associated to both Hepatocellular Carcinoma (HCC), Focal Nodular Hyperplasia (FNH), and Hepatocellular Adenoma (HCA) subtypes were evaluated. Between March 2014 and November 2021, 66 lesions were included, corresponding to: 26 HCC, 32 HCA, 6 FNH and 2 hepatic angiomyolipoma (HAML). All lesions developed on a dysmorphic liver were HCC. A non-rim arterial phase hyperenhancement with a washout and an enhancing capsule had a 98% specificity for HCC diagnosis; A homogeneous dropout of signal on the opposed phase had a sensitivity of 92% and a specificity of 89% for the diagnosis of HNF1alpha inactivated subtype of HCA (HHCA). The FNH pattern was specific at 100% for the diagnosis of FNH with a 40% Se. Finally, the accuracy of inflammatory hepatocellular adenoma (IHCA) pattern had a low 60% Se but a high 89% Sp for IHCA diagnosis. Known MRI patterns remain reliable for the accurate diagnosis of primary liver tumors on MRI even in fat-containing lesions.