Validation of Tissue Oxygenation Biomarker to Assess Healing of Diabetic Foot Ulcers using a Low-Cost Hand-Held Optical Imager
Anuradha Godavarty   (Miami, FL)
Of the nearly 29.1 million people diagnosed with Diabetes Mellitus (DM) in the USA, up to 25% develop diabetic foot ulcers (DFUs). Diabetic wounds become chronic for a variety of reasons including a suboptimal inflammatory phase of wound healing. An obstacle to development of therapies is the availability of validated biomarkers to assess healing, infection, and/or risk for recurrence. The clinical standard of assessing healing is from visual assessment of wound color, degree of epithelization, and size reduction across weeks of treatment. Oxygenation and blood flow to wound site has been measured using Doppler ultrasound (DUS), transcutaneous oxygen measurements (TCOM), hyperspectral imaging (HSI), or near-infrared spectroscopy (NIRS). While all these imaging tools have been applied in studies of DFUs, most have been limited to TO changes away from the wound (as blood flow by DUS) or at discrete points around the wound (as in TCOM and NIRS). Additionally, HSI used visible wavelengths, limiting its ability to image below the intact skin surface. There has been no validated TO-based biomarker developed to date to assess healing (subcutaneously) at the wound site during treatment. Use of NIR wavelengths allows subcutaneous imaging, unlike visible wavelengths used in HSI for surface imaging of wounds. At Optical Imaging Laboratory, we have developed a low-cost hand-held wide-field NIRS system to subcutaneously measure TO of the wound area. Our pilot studies demonstrated detection of subcutaneous TO changes at the wound site and longitudinally across weeks of care and healing. Herein, the objective is to validate and establish a TO-based biomarker for subcutaneous assessment of healing in DFUs via controlled phantom studies and longitudinal in-vivo studies across weeks of treatment. Our specific aims include: (i) Validate and calibrate the low-cost near-infrared optical scanner to measure TO changes, via controlled phantom studies;(ii) Develop a quantifiable TO biomarker for assessing healing of 10 DFUs via longitudinal studies across 4-weeks of treatment. The proposed work is innovative in obtaining subcutaneous TO maps using a low-cost, hand-held near-infrared optical scanner (NIROS) using only a few discrete wavelengths (unlike HSI), and also perform real-time non-contact imaging. The proposed study can eventually impact DFU wound care by allowing clinicians to personalize treatment plan so as to minimize TO reduction-mediated failure of healing.
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