Assessment of Tissue Oxygenation Using Multispectral Imaging

Overview

In Canada, the age-standardized prevalence of diabetes is on the rise (increasing from 3.3% in 1998/99 to 5.6% in 2008/2009 Public Health Agency of Canada (July 2011)) and is almost 1 in 10 globally. One of the most devastating complications of diabetes is the loss of a limb, (also known as lower extremity amputation, or LEA) due to complications resulting from a diabetic foot ulcer (DFU). Diabetics have a lifetime risk of 15-25% of developing a DFU1, which can lead to significant decreases in the quality of life, limitations in mobility, function and independence, and increased chance of depression and anxiety. In addition, diabetics post-LEA have high rates of mortality, with 30% dying in the first year post LEA and 70% at 5 years (more than the lifetime risk of dying from cancers). What differentiates a DFU that heals and one that progresses to LEA is often the vascularity of the limb; the diabetic lower extremity often becomes ischemic due to the vascular sequelae that are a common complication of diabetes, which hampers wound closure and immune clearance of wound-associated infections. Understanding limb oxygenation can direct treatment of a DFU, which may require limb revascularization to heal.

The MultIspectral MObile tiSsue Assessment (MIMOSA) Imager acquires digital images to calculate anatomical details of chronic wounds (e.g. diameter, surface area, and perimeter). The device can be worn from a lanyard, and clips onto a smartphone, using natural ambient lighting to capture images of a wound. The MIMOSA also uses up to 6 near-infrared LEDs to illuminate tissue with different wavelengths of light to assess tissue oxygenation. The Food and Drug Administration (FDA) has previously approved a near-infrared device called the Kent camera for the assessment of tissue oxygenation. The goal of this proposal is to assess tissue oxygenation in a group of healthy volunteers with both the MIMOSA near-infrared imaging device and the Kent Camera. The investigators hope to show that the MIMOSA Imager is substantially equivalent to the Kent Camera, and as such, the investigators are modeling the investigator's experiments on data previously published by the makers of the Kent Camera. The MIMOSA Imager is a contact-less device, and differs from the Kent Camera only in that it is smaller and more portable.