Fat Containing HCC: Findings on CT and MRI Including Serial Contrast-Enhanced Imaging

Rationale and Objectives. The purpose of this article is to review the spectrum of computed tomography (CT) and magnetic resonance imaging (MRI) findings of fat containing hepatocellular carcinoma (HCC), including serial contrast-enhanced imaging. Materials and Methods. Imaging findings of 10 fat-containing HCCs on CT (n = 2) or MRI (n = 3) or on both CT and MRI (n = 5) were retrospectively reviewed in 9 patients. Both techniques included serial contrast enhanced imaging in arterial, portal venous, and late venous phases. Results. On non-contrast CT, fat containing HCC was either homogenously hypodense (n = 6) or of mixed density (n = 1). The density values ranged between -11 and 9 HU. On MRI, homogenous (n = 4) or heterogenous (n = 4) signal loss was observed on T1-weighted out-of-phase images as compared to in-phase images. Enhancement patterns on serial contrast-enhanced CT and MRI included: arterial enhancement indistinguishable from the liver with venous wash out (n = 2), arterial capillary blush with venous phase fading (n = 2), and heterogenous arterial enhancement with unenhanced foci and venous phase wash out of enhancements. Larger lesions had late capsular enhancement. Conclusions. Fat containing HCC has spectrum of imaging findings on CT and MRI. MRI with chemical shift technique depicts the fat content. Arterial contrast enhancement with venous washout or fading may help for the diagnosis of HCC in inconclusive cases.