Thermal imaging of the skin blood flow oscillations in extremities: modification of the spectral components

Objective. The aim of the study was description of the method of skin blood flow imaging via spectral processing of the dynamic thermograms of extremities. Materials and methods. The method realized by decomposition of the temperature signal into spectral components, modification of the spectral components and inverse transform of the spectral components into a new signal, which is considered as blood flow. Modification of spectral components was accomplished taking into account skin properties, and intended for the compensation of attenuation and time lag of temperature spectral components relative to blood flow components. Results. Blood flow maps of hands during arm cuff test have been demonstrated. Blood flow values calculated from the dynamic thermogram have been validated by photoplethysmography. The technique allows restoring of the blood flow oscillations at any point of the thermogram of the object. Benefits of thermal imaging of blood flow are the following: results are not depended from the ambient light, the method not critical to the camera angle, and blood flow maps can be registered both from the whole body and small areas. The method of blood flow imaging, in a long view, applicable for the monitoring of the skin microcirculation in progression and treatment of diabetic foot syndrome, Raynaud's syndrome, as well as burn, frostbite, mechanical injury, and atherosclerosis.