The foot is the most commonly affected body part among diabetic patients leading to peripheral vascular disease. Contact based NIRS device is known to have high sensitivity and low spatial resolution. The aim is to do the 3D reconstruction of vessels in the dorsum of the foot focused on spatiotemporal features during ischemia and reactive hyperemia.
In a room with controlled temperature, the 3 healthy volunteers were asked to sit comfortably in a chair with feet flat on the floor. A pad consisting of 8 sources and detectors was placed on the right dorsum of the foot. Initial NIR signals were collected for 30 seconds with a cuff around the right leg at 0 mm Hg. After, a cuff was inflated (ischemic) at 60 mm Hg for 10 seconds (s). The pressure was maintained for 50 s before deflation (reactive hyperemia) at 0 mm Hg. The signals were collected for 3 consecutive days for each patient in a dark room and processed to obtain the spatiotemporal features. A 3D reconstruction of vessels was done to show the different responses in cuff pressure.
The result showed that intensity changes with time and on the temporal plots, it showed that as cuff pressure increases, the intensity detected also increases. In relation to the image, better vessel structures are reconstructed since more scattering and less absorption from chromophores happened.
The method allowed the extraction of spatiotemporal features. Moreover, the presentation of results in 3D reconstruction showed the effect of pressure on vessel oxygenation.