Acurácia diagnóstica da termografia cutânea por infravermelho em cadelas com neoplasia mamária

Abstract

The infrared thermography is a non-invasive thermal mapping technique, without the use of ionizing radiation, easy to perform, low cost, and of great value in medicine as an auxiliary tool in the diagnosis of various diseases, including breast neoplasms. In this context, the objective was to identify the diagnostic accuracy of cutaneous infrared thermography, as an auxiliary tool in the identification of the biological behavior and progression of mammary tumors in female dogs, as well as to verify possible association between thermographic findings and classic prognostic factors. 76 female dogs were gathered in a control group consisting of healthy animals with no history of neoplasia of any kind (n=17), and 59 female dogs subdivided into three experimental groups, according to the histopathological diagnosis of mammary tumors in: benign tumors (n=8), low-grade malignant tumors(n=27) and moderate to high-grade malignant tumors (n=38). The thermograms of each animal were evaluated for qualitative characteristics of the breast and quantitative thermal rate and distribution pattern of white, red and yellow pixels in the tumors. The performance appraisals revealed a percentage equal to 16,9% of red pixels as a limit to segregate tumors by biological behavior and tumor aggressiveness. The control group presented thermal symmetry in the breasts, and the experimental group presented asymmetries, vascular alterations, regions of tissue necrosis and an increase in the thermal average. Benign tumors showed a greater distribution of white pixels in their area, compared to malignant ones, among the malignant tumors with low to moderate/high degree of malignancy, a greater distribution of red pixels (RP) was observed, with a direct relationship between the increase in RP coverage and the degree of malignancy of the tumors. The analysis of Kaplan-Meier survival curves confirmed the previous findings, demonstrating that animals with a percentage of red pixels greater than 16,9% tend to have a lower survival rate. Based on the results obtained, thermography proved to be useful for routine clinical evaluation of mammary neoplasms in female dogs, with the potential to establish prognosis from the identification of thermal distribution patterns.