Background The thermography measures blood flow indirectly by measuring skin surface temperature . The characteristic of Raynaud phenomenon is cold-induced vasoconstriction in distal extremities which in turn, lowers skin temperature.
Objectives The aim of this study was to determine whether the infrared thermography on hands and feet is useful for diagnosis of Raynaud’s phenomenon (RP).
Methods Fifty-seven patients with RP (primary RP, n=33; secondary RP, n=24) and 120 healthy volunteers were recruited. After acclimation to room temperature for 30 minutes, patients were evaluated by thermal imaging of the palmar aspects of hands and dorsal aspects of feet. Temperature drop from palm (center) to each finger and from foot dorsum (center) to each toe were compared between RP patients and controls.
Results Temperature drop from palm to fingers and from foot dorsum to toes differed significantly between RP patients and controls. Area under the curve analysis showed that the temperature difference drop in 1st (big) toe (cutoff value: 3.11°C) best differentiated RP patients from controls (sensitivity : 72% -74%, specificity : 65 - 67%, Fig. 1).
Conclusions Thermographic assessment of the skin temperature drop from the foot dorsum to 1st toe is useful for diagnosing RP. It was previously reported that about 90% of patients presented with features of RP of the feet . Thus it clearly indicates that infrared thermography of the feet as the initial workup of Raynaud phenomenon could provide reliable data for diagnosis. In particular, the 1st toe provided the best thermographic parameter for diagnosis of RP among toes. The 1st toe is larger in size and has more obvious boundaries in imaging, which allows confident location for regions of interest to be drawn.
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Disclosure of Interest None Declared