Near-infrared fluorescence imaging methods to evaluate blood flow state in the skin lesions

Near-infrared fluorescence imaging methods have great advantages. They are fast and noninvasive. Using near-infrared photosensitizers, such as indocyanine green, it is possible to evaluate blood flow in real time. These methods find their application in problems of engraftment of skin grafts1 and in the evaluation of the severity of peripheral arterial disease during indocyanine green fluorescence angiography procedure2 . Irradiation and registration of fluorescent images and video was performed using developed video system that consists of a 785-nm laser diode, a broadband source diode, a beam splitter with a dichroic mirror and two digital CMOS cameras for recording color and luminescence images. Indocyanine green fluorescence angiography procedure was performed in 10 diabetic patients with critical lower limb ischemia. To evaluate the soft tissue perfusion of the foot diabetic patients via fluorescence angiography the following parameters have been used: T0m - time to reach maximum intensity after intravenous injection of the indocyanine green; TIm- the onset of fluorescence intensity in the area of interest; Im - the level of the maximum intensity. Regions of interest are different parts of foot near foot. Fluorescence angiography parameters were compared before and after ercutaneous transluminal angioplasty of lower limb arteries. Fluorescence images show the spread of indocyanine green in skin tissue. The degree of the formation of new blood vessels can be evaluated by intensity of fluorescence. Data from all ROI with different fluorescence angiography parameters was collected. There were significant difference in T0m and TIm in different ROI more than 10 sec.