Protocol to reproduce thermal damage in ex-vivo tissue enabling optical and thermal characterization of ablation zones

We present an experimental protocol designed to analyse the thermal and optical properties of the different tissue regions formed during microwave ablation therapies. The three regions are: a central zone of coagulative necrosis undergoing temperatures above 50 °C, a surrounding peripheral zone experiencing sub‑lethal, reversible injury within a 41–45 °C gradient, and native unaffected tissue. Microwave ablation (MWA) was performed on ex vivo bovine heart to enable systematic characterization of the optical and thermal properties of these zones. Fiber Bragg Grating (FBG) sensors were embedded in the tissue to monitor relative temperature changes during ablation, which was carried out inside a custom‑designed box. The box includes lateral slits that allow the ablated tissue to be sectioned into 9 mm slices for subsequent analysis. A hyperspectral camera acquired hypercubes of each tissue slice across the 400–1000 nm spectral range. The reduced scattering (μs’) and absorption (μa) coefficients of each ablation zone were measured using a broadband time‑domain diffuse optics spectroscopy system in transmission geometry from 600 to 1100 nm. Thermal properties (volumetric specific heat capacity, thermal conductivity and thermal