Evaluation of washout using subtraction MRI for the diagnosis of hepatocellular carcinoma in cirrhotic patients with spontaneously T1-hyperintense nodules

Purpose: The purpose of this study was to assess the value of subtraction imaging on post-arterial phase images (i.e., portal venous, delayed/transitional and hepatobiliary phases) for the non-invasive diagnosis of hepatocellular carcinoma (HCC) in spontaneously hyperintense nodules on T1-weighted imaging in patients with cirrhosis. Materials and methods: Forty-five patients with a total 55 hepatic nodules that were spontaneously hyperintense on T1-weighted images were initially retrieved. All patients underwent MRI examination of the liver using extracellular agent. Each nodule was assessed for sensitivity and specificity using LI-RADS (Liver Imaging Reporting and Data System) during two reading sessions performed first without then with subtraction images on post-arterial phase images. The final standard of reference was defined by a step-by-step algorithm previously published combining histology, typical imaging, alfa fetoprotein and follow-up. Results: Forty-six nodules (26 HCC) in 39 patients with cirrhosis were analyzed. Using LI-RADS, the sensitivity and specificity for the diagnosis of HCC were 64% (95% CI: 41-83) and 67% (95% CI: 41-87) without subtraction; and 73% (95% CI: 50-89) (P > 0.999) and 33% (95% CI: 13-59) (P = 0.553) on subtraction imaging using extracellular contrast agent. Fifty-five percent (22/40) of nodules displayed a washout without subtraction and 70% (28/40) did so on subtraction imaging obtained with extracellular contrast agent. Twenty nodules out of 40 (50%) were classified LI-RADS 5 without subtraction, and 28 out of 40 nodules (70%) with subtraction. Conclusion: The results of this study suggest that the use of subtraction imaging on post-arterial phase images (i.e., PVP, DP/TP and HBP) is not relevant for the non-invasive diagnosis of HCC for spontaneously hyperintense nodules on T1-weighted images in patients with liver cirrhosis.