Optimizing microwave ablation planning with the ablation success ratio

Area of Science:

• Hepatobiliary Surgery
• Minimally Invasive Oncology
• Medical Physics

Background:

• Hepatic microwave ablation (MWA) efficacy is challenged by unpredictable tumor size reduction due to localized vascular cooling.
• Accurate prediction of MWA outcomes is crucial for effective liver tumor treatment planning.
• Existing models often do not fully incorporate the significant impact of hepatic vasculature on ablation zones.

Purpose of the Study:

• To introduce and validate a simplified predictive model, the Ablation Success Ratio (ASR), for hepatic MWA.
• To assess the ASR's ability to predict successful ablation outcomes considering vascular cooling effects.
• To establish a reliable metric for estimating the minimum ablation radius (r_3Dmin) in the presence of simulated vascular flow.

Main Methods:

• Development of the ASR model based on the three-dimensional minimum ablation radius (r_3Dmin).
• Standardized MWAs (100 W, 5 min) performed on an ex vivo porcine liver model (n=148).
• Simulation of vascular cooling effects using a glass tube with varying flow rates (0-500 ml/min) and antenna-to-vessel distances (2.5-10.0 mm).

Main Results:

• The ASR model accurately predicted ablation success across different simulated vascular cooling conditions.
• Without cooling, 100% ASR was achieved for ablation diameters up to 20 mm.
• With simulated vascular cooling, 100% ASR was limited to ablation diameters up to 12 mm, demonstrating the model's sensitivity to cooling effects.

Conclusions:

• The Ablation Success Ratio (ASR) is a promising, simplified model for predicting hepatic MWA success.
• The ASR effectively integrates the impact of liver vascular cooling on ablation zone size.
• This model offers a valuable tool for improving the predictability and clinical success of hepatic MWA procedures.