Thermal profile of the spine for the assessment of bone metabolic disorders

Osteoporosis is a metabolic disorder characterized by high bone mineral reabsorption that reduces structural stiffness and increases fracture risk. The objective of the present study is to evaluate the feasibility of using infrared thermography, a non-invasive method, for the diagnostic of spine metabolic disorders, by comparing it with the bone densitometry exam (healthy, osteopenia, osteoporosis). This prospective study comprised 270 Caucasian women, 120 patients and 150 healthy volunteers of different ages and body mass index to compose a thermal reference profile. The thermograms were acquired with a professional Flir T-530 camera and processed using FLIR tools 6.4 and FLIR ResearchIR Max 4.40. Statistical and data analysis was carried out using MATLAB 2023b. The median temperature presented in osteoporosis diagnosis was more specific for the lumbar spine, showing a value of 33.70 °C, indicative of changes in bone metabolism compared with the control group (33.13 °C). Lumbar vertebrae (ROI 3) presented a moderate discriminatory AUC = 0.62, while the multiple linear regression model (GLM) increased AUC to 0.695 and the sensitivity to 72%. These results suggest that infrared thermography can be helpful as a complementary diagnostic technology for evaluating bone metabolic disorders, but cannot replace the gold standard images (X-Ray, MRI). It was also proposed and validated a new protocol for acquiring thermographic images of the total spine in sitting position, which is more convenient for elders and subjects with physical debilitation.