Utilizing Digital Image Speckle Correlation (DISC) for Non-Invasive Wound Healing Assessment

Traditional wound healing assessments (like visual inspection and histology analysis), face limitations because of their low accuracy and invasive nature. In severe wounds, skin grafts from the patient or biomaterials engineered constructs, are inserted into the wound site. Healing of the wound can not be determined simply by visual inspection, since it can be subjective and influenced by a variety of other factors, which can lead to inconsistent evaluations. Especially in the case of the engineered materials constructs, the integration with the underlying tissue depends on initiation of vasculature and anastomosis with underlying tissue, which is not easily apparent upon visual surface inspection . Histology analysis, while accurate, is invasive, costly, and time-consuming and can not be taken too frequently. Here we propose an alternative solution, which is non-invasive, convenient, cost effective, accurate, and hence can be applied as frequently as necessary. This method involves a modified version of elastometry, where we designed an apparatus to inflect a segment of the skin, while consecutive video images are obtained. The images are then analyzed using digital image correlation (DISC) which tracks the displacement of speckles, i.e. skin pores of hair follicles, formed on the surface of the skin under mechanical stimulation, allowing for the calculation of strain and elasticity changes. Skin elasticity and force propagation differ significantly between healthy, healing, and fully recovered tissue, making DISC an ideal tool for evaluating the healing and skin integration progress. Furthermore, DISC images can be obtained at the bedside, by the patient, and hence lends itself to remote consultation via telemedicine platforms.<br/><br/>The system was initially tested in a mouse study where the integration of an engineered scaffold was probed. DISC images taken before the incision, immediately after the incision, and at day 7 clearly showed the location of the wound which was mechanically distinct from its surroundings. This distinction decreased, but was still present at day 7, where visually complete wound closure had occurred. Histological images of the biopsy indicate that despite supervisual closure the vascular network had just begun to be established, with corresponding anastomosis. Alonger study is currently being conducted on a pig model, where a 28-day burn study on pigs is in progress. From the initial data, we can clearly see the demarcation of the wound boundary, and areas lacking integration with the underlying wound bed, even in regions where visual analysis indicated complete coverage. A full analysis of the healing process over the entire 28 day span, and a comparative evaluation of the scaffold integration process--including anastomosis and vascularization will be presented. In sum, our study thus far indicates that DISC is a promising non-invasive tool for monitoring wound healing, offering an accurate, real-time alternative to traditional methods. By quantifying skin mechanics, DISC can enhance wound care, reducing the need for invasive procedures and enabling more personalized patient management. Future work will focus on expanding the application of DISC to various wound types and conducting larger clinical trials to further validate its efficacy in diverse clinical settings.