Modeling the involution of microwave liver ablation zones

Area of Science:

• Hepatobiliary Surgery
• Medical Imaging
• Mathematical Modeling

Background:

• The post-ablation changes of microwave liver ablation zones (AZs) are not well understood.
• Characterizing AZ involution is crucial for assessing treatment efficacy and guiding follow-up strategies.

Purpose of the Study:

• To develop mathematical models for characterizing liver AZ involution after microwave ablation (MWA).
• To identify key predictors influencing the dynamics of AZ involution.

Main Methods:

• Retrospective analysis of 76 liver tumors treated with MWA in 54 patients.
• Volumetric segmentation of AZs on contrast-enhanced CT scans (CECT) from intraprocedural to follow-up imaging.
• Non-linear regression modeling to characterize AZ involution and correlate with initial tumor and ablation parameters.

Main Results:

• A total of 366 AZ segmentations were analyzed over a median follow-up of 304 days.
• Involution followed a mono-exponential decay pattern, with AZs reaching one-third of baseline volume within a year (half-life of 158 days).
• Initial tumor diameter, initial AZ volume, and tumor:AZ volume ratio significantly influenced involution dynamics (p<0.05).

Conclusions:

• Liver AZs involute rapidly after MWA, stabilizing at approximately one-third of their baseline volume within one year.
• Mono-exponential decay effectively models the involution process, which is influenced by ablated tissue characteristics.
• Predictive models for AZ involution may improve accuracy in follow-up imaging-based margin assessment and optimize ablation outcomes.