RII Track-4: Diffuse Optical Imaging for Early Detection of Diabetic Polyneuropathy

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Non-Technical DescriptionDiabetic polyneuropathy (DPN) is a common diabetic condition that results in the loss of sensation in the lower limbs. If left unchecked, this condition can lead to tissue trauma, ulcerations, infections and ultimately amputation. Since small nerve fibers innervate small blood vessels, early detection is possible by monitoring changes in tissue perfusion and blood flow. In this project, the PI will combine diffuse optics with laser-based imaging techniques to generate person-specific heat maps capable of highlighting DPN markers that include tissue perfusion and blood flow rates in feet. A model incorporating skin tones and disorders will inform the imaging data to ensure the spatial heat maps are accurate and reliable for DPN detection. This low-cost, non-invasive approach will provide opportunities for routine monitoring, providing earlier detection of small nerve fiber damage and reducing the risk of further complications. Additionally, this project establishes collaborations between the Tilbury Biophotonics group at the University of Maine with the BOTLab at Boston University which will result in several studies. Technical DescriptionDiabetic polyneuropathy (DPN), a common diabetic complication, is the loss of sensation particularly in the lower limbs and increases the risk of tissue trauma, resulting in ulcerations, infections and increased risk of amputation. Current screening approaches are unable to quantify early nerve damage despite the onset of several early symptoms including: burning, itching, restlessness, and poor thermal sensation. Current gold standard assays are due to cost and or degree of invasiveness suggesting that a new approach is needed. Small nerve fibers innervate both sweat glands and small arterioles and when damaged, both perspiration and blood flow characteristics are altered. Several functional small nerve fiber tests are based on the loss of perspiration and alterations of the rhythmic blood flow characteristics; yet excitement of each approach is dampened by low specificity or complications of skin tones and disorders. In this proposal we will build a three-wavelength Time Modulated Spatial Frequency Domain Imaging (TM-SFDI) and Laser Speckle Contrast Imaging (LSCI) system for wide-field imaging of both blood flow rates and concentrations of oxy- and deoxygenated hemoglobin. A 2-layer Monte Carlo method will minimize error due to skin tones and disorders and will also inform the selection of optimal spatial frequencies projected onto the tissue to maximize sensitivity of oxy- and deoxygenated hemoglobin. Collectively, the TM-SFDI/LSCI system is a low-cost, non-invasive approach for longitudinally monitoring diabetics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.