Directional microwave ablation in spine: experimental assessment of computational modeling.

Abstract

<h4>Background</h4>Despite the theoretical advantages of treating metastatic bone disease with microwave ablation (MWA), there are few reports characterizing microwave absorption and bioheat transfer in bone. This report describes a computational modeling-based approach to simulate directional microwave ablation (dMWA) in spine, supported by <i>ex vivo</i> and pilot <i>in vivo</i> experiments in porcine vertebral bodies.<h4>Materials and methods</h4>A 3D computational model of microwave ablation within porcine vertebral bodies was developed. <i>Ex vivo</i> porcine vertebra experiments using a dMWA applicator measured temperatures approximately 10.1 mm radially from the applicator in the direction of MW radiation (T1) and approximately 2.4 mm in the contra-lateral direction (T2). Histologic assessment of ablated <i>ex vivo</i> tissue was conducted and experimental results compared to simulations. Pilot <i>in vivo</i> experiments in porcine vertebral bodies assessed ablation zones histologically and with CT and MRI.<h4>Results</h4>Experimental T1 and T2 temperatures were within 3-7% and 11-33% of simulated temperature values. Visible ablation zones, as indicated by grayed tissue, were smaller than those typical in other soft tissues. Posthumous MRI images of <i>in vivo</i> ablations showed hyperintensity. <i>In vivo</i> experiments illustrated the technical feasibility of creating directional microwave ablation zones in porcine vertebral body.<h4>Conclusion</h4>Computational models and experimental studies illustrate the feasibility of controlled dMWA in bone tissue.