The long term goal of this research is to develop an imaging system to evaluate viability of vascularized skin grafts. Towards this end it is proposed to construct and evaluate a digitized imager that will visually display two parameters that correlate with skin graft viability. The first technique will measure differential blood volume between systole and diastole phases of arterial circulation by recording reflectance images at hemoglobin wavelengths. The second method produces fluorescence images of fluorescein in skin following systemic fluorescein infusion. In the research of Phase I, a video reflectometer/fluorometer will be constructed from a near infrared sensitive camera, frame grabber and microcomputer. Reflectance images will be synchronized with the heart beat. Procedural of software techniques will be developed to minimize interference due to skin pigmentation, scattering and tissue movement. The two methods of visualizing tissue viability will be compared with laser Doppler velocimetry to evaluate correlations among the methods and to determine the accuracy of their predictions of skin graft viability. Proof of feasibility in Phase I will lead to construction of rugged, compact, sensitive systems in Phase II for testing in a clinical research environment. These imaging systems will provide better viability prediction for plastic and reconstructive surgeons and be applicable to perfusion related disorders such as surgery for intestinal ischemia.
