Complications of the diabetic foot proliferate from ischemic and/or neuropathic conditions in the form of excess tissue build-up or callus. Plantar calluses are thick and soft and form as a result of neuropathy at the toe apices and metatarsals head and/or toe tips. Neuro-ischemic calluses appear thin, hard, dry and/or glassy and typically form at the borders of the feet and/or on main weight bearing areas. It is standard practice for the clinician to remove this excess tissue to reduce pressure in the diabetic foot which reduces the risk of ulceration. The dead tissue layers are removed in a surgical process known as scalpel debridement, or chiropody. It is not uncommon for a clinician to encounter a buried wound in the process of scalpel debridement. However, the process itself is not straightforward in that the extent of debridement is not measurable between clinicians. The debridement process removes tissue up to the epidermal-dermal junction, which may be difficult to identify for an inexperienced clinician. In an effort to measure the effect of scalpel debridement, near infrared (NIR) imaging was applied in an IRB study between Florida International University and Dr. Mohan’s Diabetes Specialties Centre in Chennai, India. Subjects were assessed before and after the debridement procedure. NIR images at multiple wavelengths were obtained before and after debridement to estimate changes in tissue oxygenation in the callus and surrounding peri-callus regions. A method to analyze the significance of oxygenation change occurring both overall and within sub-quadrants of the callus is conducted to assess the effect of debridement. Measuring changes in tissue oxygenation may potentially be used in future clinical applications to improve the debridement process and reduce the risk of ulceration.
Diabetic Foot Ulcers (DFUs) are responsible for 20% of diabetic-related hospitalization and 85% of diabetes related amputations. In DFUs the primary factor affecting healing is an adequate oxygen supply to the wound. However, the gold standard approach for assessing DFUs is by evaluating the reduction of wound size over a four-week period. In this study, we investigate the potential of altered breathing patterns as a technique to assess localized oxygenated perfusion in DFUs as a measure of healing potential. A continuous wave (CW), non-contact, near infrared optical scanner (NIROS) was used to conduct NIR based spectroscopic imaging at dual discrete wavelengths (729nm and 799nm) on DFUs with 7mW of maximum optical power. Subjects were imaged at discrete time points and dynamically utilizing an altered breathing paradigm (i.e. breath-hold) to measure the relative oxy- (ΔHbO) and deoxyhemoglobin (ΔHbR) changes in normal and DFU scenarios. Results show that in normal individuals, ΔHbO/ΔHbR changes at all points of the foot because of altered breathing patterns are synchronous; whereas in the DFU scenario changes in hemodynamic parameters are asynchronous. This indicates that under normal circumstances, oxygenated perfusion changes are consistent and uniform at all points of the foot as opposed to the DFU scenario’s inconsistent oxygenated perfusion. Altered breathing paradigms may serve as a useful tool in assessing localized sub-surface oxygenated perfusion in regions around the wound, and help clinicians better cater the treatment process.
Smartphone based wound image analysis approach has been recently developed to capture high resolution digital images of the wound and determine the wound size via image segmentation algorithms. Smartphone based technology has also been developed to obtain spectroscopic information at discrete point locations for brain imaging applications. Herein, we developed a low-cost smartphone based near-infrared (NIR) imaging device (between 650-1000 nm) that can measure tissue oxygenation in order to analyze wound healing status. Oxygen supply to ulcers is a key limiting factor for successful healing, and hence changes in tissue oxygenation are a precursor to visual changes in the wound. The use of multi-wavelength near-infrared light allows subcutaneous mapping of oxy- and deoxy-hemoglobin changes (or in turn tissue oxygenation changes). Validation studies were performed in controls to demonstrate changes in oxygenation (from diffuse reflectance changes) in response to venous occlusion. Currently, studies on diabetic foot ulcers is carried out using the cell phone-based imaging tool to obtain sub-surface tissue oxygenation maps of the wound and its surrounding. Smartphone based assessment of wounds will assist clinicians and nurses in any clinical in-house setting including low resource settings. In future, patients with chronic wounds can also actively participate (and comply) in their treatment process.