Hyperspectral Imaging in Diabetic Foot Wound Care

Abstract

Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of type 1 and 2 diabetes patients during their lifetime. If untreated, diabetic foot ulcers may become infected and require total or partial amputation of the affected limb. Early identification of tissue at risk of ulcerating could enable proper preventive care, thereby reducing the incidence of foot ulceration. Furthermore, noninvasive assessment of tissue viability around already formed ulcers could inform the diabetes caregiver about the severity of the wound and help assess the need for amputation. This article reviews how hyperspectral imaging between 450 and 700 nm can be used to assess the risk of diabetic foot ulcer development and to predict the likelihood of healing noninvasively. Two methods are described to analyze the in vivo hyperspectral measurements. The first method is based on the modified Beer-Lambert law and produces a map of oxyhemoglobin and deoxyhemoglobin concentrations in the dermis of the foot. The second is based on a two-layer optical model of skin and can retrieve not only oxyhemoglobin and deoxyhemoglobin concentrations but also epidermal thickness and melanin concentration along with skin scattering properties. It can detect changes in the diabetic foot and help predict and understand ulceration mechanisms

Hyperspectral imaging for early detection of oxygenation and perfusion changes in irradiated skin

“…Data were analyzed online using a fiducial target to achieve spectral decomposition and two-dimensional image registration techniques. 10 Diffuse reflectance tissue spectra were determined for each pixel within this collection of images using proprietary algorithms. Using standard spectra for Hb-oxy and Hb-deoxy to decompose a 79-pixel-diameter region, mean Hb-oxy and Hb-deoxy values of the irradiated area were obtained.…”

“…Hb-oxy, Hb-deoxy, and tHb are reported as arbitrary values that have previously been shown to correlate well with respective in vivo molar concentrations. 10 Prior to imaging, the system was calibrated to a reference card (CheckPad TM , HyperMed TM , Inc.) for all acquisitions, and pixel reflectance was determined relative to this standard reflectance. A fiducial target was used to correct for motion artifact from respiratory effort.…”

“…8,9 HSI is a method of wide-field diffuse reflectance spectroscopy that utilizes a spectral separator to vary the wavelength of light entering a digital camera and provides a diffuse reflectance spectrum for every pixel. These spectra are then compared to standard transmission solutions to calculate the concentration of oxyhemoglobin (Hb-oxy) and deoxyhemoglobin (Hb-deoxy) in each pixel, from which spatial maps of tissue oxygenation are constructed as previously described by Yudovsky et al 10 OxyVu TM -2 (HyperMed TM , Inc. Greenwich, Connecticut) is a commercially available device that generates tissue oxygenation maps of the subpapillary plexus. This modality provides simultaneous measurements of cutaneous tissue oxygenation and perfusion that is both noninvasive and reproducible.…”

Multimodal imaging of cutaneous wound tissue

“…[3][4][5][6][7] Several multispectral image systems have been successfully applied to assess skin diseases 8,9 and wound healing. [10][11][12] In addition to oxygen saturation, blood vessel evolution is also involved in different phases of wound healing for continuous supply of oxygen and nutrition. 2 In this regard, laser speckle imaging provides a high resolution optical method for monitoring tissue hemodynamics and vessel redistribution.…”

An average enumeration method of hyperspectral imaging data for quantitative evaluation of medical device surface contamination

“…Therefore, both spectral and spatial information are acquired at the same time, enabling the HSI technique to be optimized for complex object with mixture of different materials. Public health benefit using this technique ranges from quality and safety inspection of agriculture products [21][22][23] to tissue oxygenation monitoring in human body [24,25].…”