Laser Interstitial Thermotherapy for pancreatic tumor ablation: theoretical model and experimental validation

Abstract

This study aims to develop and verify a theoretical model to reproduce the thermal response of pancreatic tissue undergone Laser Induced Interstitial Thermotherapy (LITT). The model provides the evaluation of: a) ablated volumes induced by thermal ablation; b) tissue response time to irradiation; and c) heat extinction time. Theoretical volume values were compared with ex vivo healthy tissue and in vivo healthy and neoplastic tissue volume values. The theoretical model takes into account the differences between healthy and neoplastic tissue due to blood perfusion. Mathematical model shows that ablated volume of ex vivo healthy tissue is greater than in vivo one after the same treatment. Moreover, ablated neoplastic in vivo tissue volume is greater than healthy in vivo one, because of tumour angiogenesis. Ablated volume values were compared with experimental data obtained by laser treatment of 30 ex vivo porcine pancreases. Experimental ablated volume values show a good agreement with theoretical values, with an estimated increase of 61% when power increases from 3 W to 6 W, versus 46% of experimental data, and an estimated increase of 14% from 6 W to 10 W, versus 21% of experimental values. LITT could be an alternative or a neo-adjuvant treatment to surgical resection for pancreas cancer removal, and the proposed model could be the basis to supervising the evolution of ablated volumes during tumor treatment.