Enhanced Thermal Imaging a Novel Imaging Technique for Monitoring Re-Perfusion Post-Operatively

We are developing a real-time infrared image technique, Enhanced Thermal Imaging (ETI), that can detect blood vessels embedded in tissue and assess tissue perfusion. ETI is a combination of standard thermal imaging (8-10 µm) and selective heating of blood relative to surrounding water-rich tissue using LED sources at low power. Blood absorbs strongly at 530 nm. Illumination of water rich tissue and embedded blood vessels at this wavelength selectively increases the temperature of the blood vessels relative to the surrounding tissue causing the vessels to appear brighter in a thermal image. ETI does not require the use of injectable dyes and has a compact footprint allowing for use both during surgery and at the bedside. Previous studies using ETI were limited due to lengthy post-processing times required to delineate vessels. The first study presented in this dissertation shows the real-time capabilities of ETI in mapping vascular structures. Real time application of computational filters highlighting temporal and spatial changes reveal embedded blood vessels. ETI was obtained for a model with simulated blood vessels and a porcine heart tissue, and for both models, temporal and spatial filters outperformed standard thermal imaging. In the second study, ETI was simulated computationally to determine limitations and optimizations. The models were also analyzed to determine parameters that can delineate vessel depth and size and these results were compared with ex vivo tissue studies. The final study involved monitoring the reperfusion of skin flaps in a murine model. ETI appears to be more sensitive to the deeper healing while fluorescent imaging provides information about superficial healing. The use of intra-operative and post-operative optical guidance has beneficial impacts on patient costs and tissue viability.