PROspective Multi-center study to Evaluate the correlation between safety margin and local recurrence after THErmal ablation USing image co-registration in patients with hepatocellular carcinoma

Problem description
Compared to thermal ablation, the complication rate in surgically treated HCC patients is much higher with an odds ratio of 8.24 (95% CI: 2.12-31.95). Yet, surgical resection yields better results regarding local recurrence (HR 0.38 (95% CI: 0.17-0.84)). Therefore, surgical resection remains the treatment of choice for most patients with BCLC 0/A HCC, despite higher morbidity and mortality rates. For thermal ablation to become truly competitive with surgical resection, the issue of local recurrence needs to be addressed.
Ablation systems have predefined algorithms, based on in vitro experiments, to predict size and shape of the ablation. In general, ablations setting are chosen that would result in complete tumor ablation with a safety margin of >5mm, but the actual ablation zone may be smaller than expected and deformed as a result of factors such as inhomogeneous tissue density, liver cirrhosis and heat-sink.
After surgical resection, a pathologist examines the resected specimen to confirm complete resection. After ablation, confirmation of successful ablation can only be obtained using imaging modalities. Currently there is no validated, standardized method to accurately determine safety margins. Most commonly, the interventional radiologist performing the procedure estimates the safety margins by visual qualitative assessment of pre- and post-ablation contrast-enhanced CT (CECT). This method is associated with high interobserver variability and lacks accuracy. There is a need for a method that allows more accurate assessment of safety margins after ablation.

Solution
Over recent years, post-processing software has become available that allows co-registration of pre- and post-ablation CECT. This allows three-dimensional quantitative assessment of ablation margins. Such quantification of ablation margin would allow immediate evaluation of ablation margins and reablation during the same treatment session if margins are deemed to be insufficient. It would potentially be the equivalent of the frozen section that is used for real-time margin control during surgery.
Retrospective studies have demonstrated the potential value of quantitative assessment of ablation margins after thermal ablation, but this has neither been validated in prospective studies nor in larger patient groups. In a prospective, multi-center, non-experimental study in patients undergoing ablation for BCLC 0/A/B HCC, safety margins will be quantitatively assessed using dedicated co-registration software.
The aim of this project is to correlate ablation margins with outcome to determine the relationship between ablation margins and local recurrence and set the optimal threshold for minimal ablation margin.

Over recent years, post-processing software has become available that allows co-registration of pre- and post-ablation CECT. This allows three-dimensional quantitative assessment of ablation margins. Such quantification of ablation margin would allow immediate evaluation of ablation margins and reablation during the same treatment session if margins are deemed to be insufficient. It would potentially be the equivalent of the frozen section that is used for real-time margin control during surgery.

- Registration
- Ablation
- Follow-up every 3-4 months until 3 years