Analysis and diagnosis of basal cell carcinoma (BCC) via infrared imaging

In this work, a structured methodology is proposed and tested through infrared imaging temperature measurements of a healthy control group to establish expected normality ranges and of basal cell carcinoma patients (a type of skin cancer) previously diagnosed through biopsies of the affected regions. A method of conjugated gradients is proposed to compare measured dimensionless temperature difference values (Δθ  ) between two symmetric regions of the patient’s body, that takes into account the skin, the surrounding ambient and the individual core temperatures and doing so, the limitation of the results interpretation for different individuals become simple and nonsubjective. The range of normal temperatures in different regions of the body for seven healthy individuals was determined, and admitting that the human skin exhibits a unimodal normal distribution, the normal range for each region was considered to be the mean dimensionless temperature difference plus/minus twice the standard deviation of the measurements (Δθ¯mean±2σΔθ¯) in order to represent 95% of the population. Eleven patients with previously diagnosed basal cell carcinoma through biopsies were examined with the method, which was capable of detecting skin abnormalities in all cases. Therefore, the conjugated gradients method was considered effective in the identification of the basal cell carcinoma through infrared imaging even with the use of a low optical resolution camera (160 × 120 pixels) and a thermal resolution of 0.1 °C. The method could also be used to scan a larger area around the lesion in order to detect the presence of other lesions still not perceptible in the clinical exam. However, it is necessary that a temperature differences mesh-like mapping of the healthy human body skin is produced, so that the comparison of the patient Δθ could be made with the exact region of such mapping in order to possibly make a more effective diagnosis. Finally, the infrared image analyzed through the conjugated gradients method could be useful in the definition of a better safety margin in the surgery for the removal of the lesion, both minimizing esthetics damage to the patient and possibly avoiding basal cell carcinoma recurrence.

► We present and test a methodology with potential for identifying basal cell carcinoma through infrared imaging. ► A method of conjugated gradients is proposed to use human bilateral symmetry. ► A control group is used to determine skin normality ranges. ► Eleven diagnosed basal cell carcinoma patients were examined with the method to successfully test effectiveness. ► A temperature differences mesh-like mapping of the healthy human body skin is necessary for more effective diagnosis.