Avaliação de fatores técnicos e individuais em exames termográficos faciais

Abstract

INTRODUCTION: Infrared thermography is a non-invasive, non-ionizing and painless diagnostic method, which maps the distribution of thermal radiation from the body's surface in images and which can significantly contribute to aiding the diagnosis and treatment planning of numerous orofacial changes. The acquisition of infrared thermography requires compliance with several technical and individual factors that can influence both the evaluation and interpretation of the images. Therefore, it is necessary to use a protocol to adjust the influence of these factors. OBJECTIVE: This project aimed to evaluate the influence of technical and individual factors on the performance of facial thermographic examinations. MATERIALS AND METHODS: This was a cross-sectional, descriptive, analytical study, carried out at the Thermography Laboratory of the Department of Dentistry of the State University of Paraíba – UEPB, Campus I and had spontaneous demand, made up of volunteers recruited from that department. The sample was composed of convenience, totaling 392 thermograms and 2,352 ROIs evaluated. The study was carried out in three phases: 1. Recruitment/screening/orientation, 2. Interview and data collection, 3. Thermographic examination. To evaluate the influence of skin acclimatization, thermographic images were acquired with a FLIR T650sc thermal camera at a distance of 80 cm from the volunteer, in the area of the laboratory where there is thermal insulation on the wall. Thermographic examinations followed the guidelines provided by the American Academy of Thermology – AAT. For this evaluation, thermographic acquisitions were carried out when the volunteer arrived at the laboratory to take the images, and in a second moment, after 20 minutes for the period of thermal stability of the skin. To evaluate the influence of the distance from the camera to the volunteer, thermographic acquisitions were carried out at distances of 30cm, 80cm and 100cm. All images were taken on a thermally insulated wall. To evaluate the influence of the wall's thermal insulation, a camera/volunteer distance of 80 cm was used, and acquisitions were made in the region where the wall's insulating barrier is located and where there was no such insulating barrier. The regions of interest determined for the analysis were the nasolabial region, lip commissure (right and left) and the lower lip. A descriptive analysis of data relating to sociodemographic and anthropometric variables was carried out. The normality standard of the data was assessed using the Kolmogorov-Smirnov test using the Lilliefors correction. Using the Spearman test, correlations between the temperatures of the areas of interest and age and BMI were performed. To compare the areas of interest according to skin color, the t and Mann-Whitney tests were used according to whether or not the data distribution was normal. For comparisons of technical influencing factors, the Friedman and Wilcoxon statistical tests for bivariate comparisons and the Wilcoxon test were used. RESULTS: The average age of the sample was 22 years old, with 47 female volunteers and 9 male volunteers, with a BMI of adequate weight in 69.6% of the volunteers. It was not possible to observe a positive correlation between the temperatures of the areas of interest and age and BMI. There was a significant association between the distances of 30 cm, 80 cm and 100cm for all ROIs analyzed (p<0.001), as well as between the variables with/without acclimatization, for the nasolabial ROI (p<0.001) and lower lip (0.045) . For the comparison with and without insulation of the back wall, there was no positive association. CONCLUSION: It can be concluded that the technical factors of acclimatization time and distances for acquiring thermographic images can interfere with the interpretation of the acquired images.