A new smartphone-based method for wound area measurement

Abstract

Proper wound healing can be assessed by monitoring the wound surface area. Its reduction by 10 or 50% should be achieved after 1 or 4 weeks, respectively, from the start of the applied therapy. There are various methods of wound area measurement, which differ in terms of the cost of the devices and their accuracy. This article presents an originally developed method for wound area measurement. It is based on the automatic recognition of the wound contour with a software application running on a smartphone. The wound boundaries have to be traced manually on transparent foil placed over the wound. After taking a picture of the wound outline over a grid of 1 × 1 cm, the AreaMe software calculates the wound area, sends the data to a clinical database using an Internet connection, and creates a graph of the wound area change over time. The accuracy and precision of the new method was assessed and compared with the accuracy and precision of commercial devices: Visitrak and SilhouetteMobile. The comparison was performed using 108 wound shapes that were measured five times with each device, using an optical scanner as a reference device. The accuracy of the new method was evaluated by calculating relative errors and comparing them with relative errors for the Visitrak and the SilhouetteMobile devices. The precision of the new method was determined by calculating the coefficients of variation and comparing them with the coefficients of variation for the Visitrak and the SilhouetteMobile devices. A statistical analysis revealed that the new method was more accurate and more precise than the Visitrak device but less accurate and less precise than the SilhouetteMobile device. Thus, the AreaMe application is a superior alternative to the Visitrak device because it provides not only a more accurate measurement of the wound area but also stores the data for future use by the physician.

Keywords: Diabetic foot ulcer; Smartphone application; Wound area measurement; Wound healing.