Effect of Non-parallel Applicator Insertion on 2.45 GHz Microwave Ablation Zone Size and Shape

Microwave ablation is used clinically to thermally ablate cancerous tissue in the liver and other organs. Physicians may use multiple applicators simultaneously when treating large tumor volumes. Preclinical simulation and experimental studies most often presume parallel insertion of applicators. However, due to anatomical constraints, such as the presence of ribs and the diaphragm, it may be challenging to insert applicators in a parallel configuration. Here, we describe computational models of dual-antenna microwave ablation that account for the effects of temperature-dependent changes in tissue properties. We have also implemented a system for experimental assessment of dual-antenna microwave ablation profiles in ex vivo tissues. Utilizing 3D printing, we have constructed a device that precisely positions antennas within experimental tissue samples and allows for accurate sectioning of the ablation zone relative to the plane of antenna insertion. Furthermore, we implemented image processing techniques for quantifying the size and shape of experimental ablation zones. This enables more accurate and repeatable comparisons of ablation profiles between simulations and experiments. We found that for an inter-antenna spacing ranging from 10 to 20 mm, simulations and experiments indicated that non-parallel antenna insertion results in ablation zone volumes that may change by up to 30%.
(Copyright 2019, The Author(s).)