Directional microwave ablation in spine: experimental assessment of computational modeling

Abstract

Background

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 ex vivo and pilot in vivo experiments in porcine vertebral bodies.

Materials and methods

A 3D computational model of microwave ablation within porcine vertebral bodies was developed. Ex vivo 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 ex vivo tissue was conducted and experimental results compared to simulations. Pilot in vivo experiments in porcine vertebral bodies assessed ablation zones histologically and with CT and MRI.

Results

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 in vivo ablations showed hyperintensity. In vivo experiments illustrated the technical feasibility of creating directional microwave ablation zones in porcine vertebral body.

Conclusion

Computational models and experimental studies illustrate the feasibility of controlled dMWA in bone tissue.

Keywords:

• Microwave ablation
• bone ablation
• bone tumor
• thermal ablation
• directional antenna

Disclosure statement

Austin Pfannenstiel discloses being the founder of Precision Microwave, Inc. and an inventor on patents owned and licensed by Precision Microwave. Punit Prakash discloses being the subaward-PI on NSF grant IIP 1951186 and an inventor on patents owned and licensed by Precision Microwave. The authors alone are responsible for the content and writing of the paper.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

This work was support by National Science Foundation (NSF) grant IIP 1951186 and MSK is funded through the NIH/NCI Cancer Center Support Grant P30 CA008748.