Analysis of hyperspectral camera settings for assessing liver tissue thermal damage

Hyperspectral imaging (HSI) is gaining, tremendous acceptance as an innovative non-invasive approach in the medical field. HSI is a sensing technique combining spectral and spatial information of the object of interest. Preliminary works have investigated the use of HSI for the intraoperative guidance of minimally invasive therapy such as thermal therapies. Data collected by the HSI system carry information of the tissue texture and may potentially track structural modifications caused by thermal treatment providing an alternative approach to the direct monitoring of the thermal outcome induced during the treatment. In this work, a commercial hyperspectral (HS) camera, working in the visible and near-infrared spectral range, has been tested for the estimation of thermal damage in the ex vivo liver. Firstly, the optimal experimental setup and settings to evaluate the optical response of tissues with the HSI were identified. Then, the reflectance of not-damaged tissue (room temperature) and tissue subjected to thermal damage was acquired and compared. Specifically, the damage was induced by homogeneously heating the tissue until reaching 50.0 degrees C and 70.0 degrees C. Inter-individual and intra-individual variability analysis was also computed using multiple samples and showed that by using the first derivative of reflectance the sources of variability are minimized. Furthermore, the first derivative shows variation in the shape mainly localized in the range [600-700] nm for the tissue subjected to 70.0 degrees C. The peak at 650 nm red-shifted and increased to reach 680 nm. A decrease at 945 nm is also visible for the damaged tissue with a preparation temperature of 70.0 degrees C as well as a slope variation in the range [800-900] nm. These results confirm the potential of using the hyperspectral camera to assess different levels of damage during thermal therapies encouraging additional studies to validate its use as a monitoring tool.