Nodules Identified on Surveillance Ultrasound for HCC: CEUS or MRI as the Initial Test?

Abstract

Following positive surveillance ultrasound (US), magnetic resonance imaging (MRI) is recommended for further characterization. We propose contrast-enhanced ultrasound (CEUS) shows equivalent efficacy. This prospective institutional review board approved study recruited 195 consecutive at-risk patients with a positive surveillance US. All had CEUS and MRI. Biopsy (n=44) and follow-up are gold standard. MRI and CEUS results are classified according to liver imaging reporting and data system (LI-RADS)and patient outcome. As an US-based modality, CEUS is superior in confirming findings from surveillance US, correlation in 189/195 (97%) on CEUS compared to 153/195 (79%) on MRI. Within these negative MRI examinations, there are 2 hepatocellular carcinoma (HCC) and 1 cholangiocarcinoma (iCCA) diagnosed on CEUS and proven by biopsy. From 195 patients, there are 71 malignant diagnoses from all sources, including 58 LR-5 (45 on MRI and 54 on CEUS) and 13 others, including HCC outside of LR-5 category, and LR-M with biopsy proven iCCA (3 on MRI and 6 on CEUS). CEUS and MRI show concordant results in the majority of patients (146/195,75%), including 57/146 malignant and 89/146 benign diagnoses. There are 41/57 concordant LR-5 and 6/57 concordant LR-M. When CEUS and MRI are discordant, CEUS upgraded 20 (10 biopsy-proven) from MRI LR-3/4 to CEUS LR-5 or LR-M by showing washout (WO) that MRI failed to show. Additionally, CEUS characterized time and intensity of WO and diagnosed 13/20 LR-5 by showing late and weak WO and 7 LR-M by showing fast and marked WO. CEUS is 81% sensitive and 92% specific in diagnosing malignancy. MRI is 64% sensitive and 93% specific. CEUS performance is at least equivalent if not superior to MRI for initial evaluation of lesions from surveillance US.