Post-Operative Monitoring of Tissue Perfusion in Skin Flaps in a Murine Model Using Enhanced Thermal Imaging

Inadequate tissue perfusion is a fundamental cause of early complications following a range of procedures including the creations of skin flaps/grafts during reconstructive microsurgery and complex closures during amputation. Clinical examination remains the primary means of evaluating tissue perfusion intraoperatively. Recently, indocyanine green (ICG) angiography has been used as an adjunt to physical examination. However, ICG angiography is an invasive procedure that requires the intravenous application of a fluorescent dye. Enhanced thermal imaging (ETI) is a non-invasive, real-time infrared imaging technique that can detect blood vessels embedded in soft tissue. ETI uses selective heating of blood via illumination with a green (532 nm) LED to produce a thermal contrast (>= 0.5.degrees C) between blood vessels and surrounding water-rich tissue. Vessel-rich regions appear brighter in the thermal image. ETI does not require the use of dyes and recent improvements to the acquisition software have enabled real-time imaging. The compact footprint of the system could allow for use both intraoperatively and at the bedside. In this study we evaluate the ability of ETI to assess tissue perfusion of skin flaps in a murine model. The healing and perfusion of these flaps was monitored via the density of capillary beds and vascular networks using visual inspection, fluorescent imaging, and ETI over a 12-day study period. We compare the ability of these techniques to detect early indications of necrosis and re-vascularization in grafts.