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.

Development and characterization of a Fibre Bragg Grating temperature probe for medical Laser Ablation therapy

“…Recently, FBG sensors have been employed to monitor tissue temperature during LA therapy. They show valuable characteristics for such application with respect to thermocouples, such as immunity from electromagnetic interferences and MRI-compatibility [5][6][7][8], which allow employing FBG during MRI-guided laser procedures. The main drawback is their sensitivity to strain, which could entail measurement error during in vivo application, where patient respiratory movements can strain the FBG.…”

Multiparameter point sensing with the FBG-containing multicore optical fiber

“…Laser energy absorption and its transformation to heat near the applicator's tip leads to tumor cell death during LA. LA has been used for prostate, liver, kidney, lung [10], and pancreas [11], [12]. Despite the abovementioned advantages, LA can still present incomplete ablation and disease recurrence due to the low selectivity of laser light with respect to the tumor tissue, hence leading to possible damage to surrounding healthy tissues.…”

Characterization of fiber optic distributed temperature sensors for tissue laser ablation

“…LA is similar to other minimally invasive alternatives to surgical resection, such as Radio-Frequency Ablation (RFA) or MicroWave Ablation (MWA), but exploits the absorption of laser light from tissue to locally increase the temperature above cytotoxic levels (60 • C). This approach has become one of the elective treatments for small (less than 2 cm) solid tumors [12]; however, despite its increasing adoption, the outcomes could be further improved with the adoption of proper real-time temperature measurement systems, given the difficulty in predicting a priori the size of the area where cytotoxic temperature levels are reached without causing carbonizations [13]. The developed probe could help overcoming these limitations.…”