Real-time US-CT/MR fusion imaging for percutaneous radiofrequency ablation of hepatocellular carcinoma

Background & aims: Although ultrasonography (US) guided radiofrequency ablation (RFA) is a commonly used treatment option for early hepatocellular carcinoma (HCC), inconspicuous tumors on US limits its feasibility. Thus, we prospectively determined whether real-time US-CT/MR fusion imaging can improve the technical feasibility of RFA compared with B-mode US, and help predict local tumor progression after RFA in patients with HCC.

Methods: A total of 216 patients with 243 HCCs ⩽5cm referred for RFA were prospectively enrolled. Prior to RFA, the operators scored the visibility of tumors, and technical feasibility on a 4-point scale at both B-mode US and fusion imaging. RFA was performed with a switching monopolar system using a separable cluster electrode under fusion imaging guidance. Technique effectiveness, local tumor progression and intrahepatic remote recurrences were evaluated.

Results: Tumor visibility and technical feasibility were significantly improved with fusion imaging compared with B-mode US (p<0.001). Under fusion imaging guidance, the technique effectiveness of RFA for invisible tumors on B-mode US was similar to those for visible tumors (96.1% vs. 97.6%, p=0.295). Estimated cumulative incidence of local tumor progression at 24months was 4.7%, and previous treatment for other hepatic tumors (p=0.01), higher expected number of electrode insertions needed and lower technical feasibility scores (p<0.01) on fusion imaging were significant negative predictive factors for local tumor progression.

Conclusion: Real-time fusion imaging guidance significantly improved the tumor visibility and technical feasibility of RFA in patients with HCCs compared with B-mode US, and low feasibility scores on fusion imaging was a significant negative predictive factor for local tumor progression.

Lay summary: US/CT-MR fusion imaging guidance improved the tumor visibility and technical feasibility of RFA in patients with HCCs. In addition, fusion imaging guided RFA using multiple electrodes demonstrated a high technique effectiveness rate and a low local tumor progression rate during mid-term follow-up. Clinical trial number: ClinicalTrials.gov number, NCT02687113.