Metabolic.Care: Development and characterization of a new thermographic platform for diabetic foot detection

Summary form only given. Foot complications due to diabetes - diabetic foot disease - constitute an important economic burden on healthcare systems and impose a loss of quality of life for the patients, leading to limb-threatening (amputation) in most circumstances. Over the last years, several studies have demonstrated that there is a correlation between increased temperature and diabetic foot condition and that temperature augmentation may be detected at a reversible phase of the disease. Conventional non-invasive methods to assess foot temperature include physical palpation or infrared (IR) thermometry. However, the increase in temperature is typically too slight to be detected manually while taking foot temperature with a thermometer is very time consuming and provides only discrete values. The ideal instrument should provide fast temperature readings of the entire foot in one measurement procedure. Although a few technologies are available (liquid crystal thermography, IR cameras, etc.), none has been adopted in clinical practice up till now. This paper proposes a novel thermographic platform for diabetic foot detection based on a thermochromic liquid crystal (TLC) sheet and a modified A3 scanner that acquires images from the TLC sheet. Both elements are enclosed in a metallic and ergonomic structure that allows their physical support. The image is obtained when the patient, in a sitting position, places his feet on the TLC sheet and is subsequently analysed using dedicated image processing algorithms. The significant advantage of this system over the state of the art is the capability to obtain several subsequent images during dynamic changes in skin temperature, making the necessary human intervention minimal. Furthermore, the system is connected to an application hosted on the eVida web platform that allows data uploading, processing and the creation of alarms. The thermographic platform was characterized in a bench test, using two novel Peltier-based calibration systems, and with the feet of a healthy subject. Aspects related to differential thermal resolution of the TLC sheet, contact time between the calibration system/foot with the TLC sheet, the cooling process of the platform and image resolution were tested. The new platform demonstrated a very good performance on the bench and in vivo tests and results showed that it was possible to detect thermal differences between 1o C - 1.6o C (bench tests). Although in vivo studies will be extended to a more significant number of subjects to differentiate between healthy/non-healthy groups, this thermographic platform appears to be a promising and easy to use alternative to detect and monitor diabetic foot condition in a medical environment.