Clinical Significance of Intratumoral Contrast Pooling on Contrast-Enhanced CT After Atezolizumab Plus Bevacizumab for Unresectable Hepatocellular Carcinoma.

Recent advances in systemic therapies have improved clinical outcomes for patients with unresectable hepatocellular carcinoma (uHCC), as shown in randomized phase 3 clinical trials. Given the availability of alternative systemic regimens, an early imaging biomarker of treatment efficacy is crucial to avoid delays in deciding whether to continue the current regimen or switch to another therapy. We report two cases of uHCC that demonstrated patchy pooling of contrast material within the tumor on early follow-up contrast-enhanced computed tomography after the initiation of atezolizumab combined with bevacizumab (AB therapy), an imaging feature consistent with the vascular lake-like phenomenon. In both cases, this imaging feature appeared at the first response assessment after several cycles, and each patient achieved a partial response as the best overall response per Response Evaluation Criteria in Solid Tumors version 1.1. Subsequently, each patient underwent or was considered for conversion therapy. The vascular lake-like phenomenon may represent an early imaging biomarker of treatment efficacy following AB therapy.