Imaging appearance of residual HCC following incomplete trans-arterial chemoembolization on contrast-enhanced imaging.

Purpose: The aim of this study was to describe changes in contrast agent kinetics in HCC following incomplete trans-arterial chemoembolization (TACE) on contrast-enhanced ultrasound (CEUS) and MRI/CT.

Methods: Patients with residual HCC proven by biopsy, retreatment angiography, or 4-8 month MRI demonstrating tumor progression were identified. Pre-treatment and 4-6-week follow-up CE-MRI/CT and CEUS exams were collected for blinded reads by two experienced readers for each modality to evaluate arterial phase hyper-enhancement (APHE) and washout within the residual HCC. A third reader provided tie-breaking decisions for any disagreements.

Results: Contrast-enhanced imaging data were collected from 29 patients with residual HCC post-TACE. On CEUS, 84.2% of patients with baseline APHE demonstrated APHE post-TACE (p = 0.25). On CE-MRI/CT, 57.1% of patients with baseline APHE later demonstrated APHE (p = 0.004). As for washout, on CEUS 33.3% of patients with baseline washout retained washout post-TACE (p = 0.01), while on CE-MRI/CT only 18.8% of patients with baseline washout later demonstrated washout (p < 0.001). Among CEUS readers, reader agreement was 100% for baseline APHE, 66.7% for baseline washout (K = 0.35), 84.2% for post-TACE APHE (K = 0.35), and 57.9% for post-TACE washout (K = - 0.09). On CE-MRI/CT, reader agreement was 65.5% for baseline APHE (K = 0.19), 55.2% for baseline washout (K = 0.12), 48.3% for post-TACE APHE (K = - 0.07), and 58.6% for post-TACE washout (K = 0.04).

Conclusion: Common diagnostic features of treatment-naïve HCC like APHE and washout can be substantially altered by TACE and should be considered when diagnosing residual disease on contrast-enhanced imaging.