Temperature dependence iteration of the optical properties of porcine tissue.

The study of the optical properties of a biological sample can be of great interest for the minimally invasive thermal treatment of tumors. We exploited a unique workstation for time-domain broadband diffuse optical spectroscopy to disentangle the absorption and scattering coefficient of a turbid sample based on the photon time of flight. We present a study on the evolution in time of the absorption and scattering coefficient during thermal treatment of a biological muscle sample using a thermal bath. We measured a slower rate of change in the scattering coefficient compared to the absorption coefficient. Different processes govern the two coefficients. The scattering coefficient is related to the tissue microstructure. It increases with cell membrane destruction and protein denaturation caused by heat. The absorption coefficient is related to the chemical composition such as water content and the reaction of the hemoglobin into deoxyhemoglobin. This study is relevant since it can help in deciphering the tissue transformation during thermal treatment, and open to photonics technologies assisting the surgeon in grading the treatment during minimally invasive interventions.