Infrared thermography in screening for normal endothelial function

This database is the result of a diagnostic test type research in which we measured Brachial arterial diameter (BAD) at baseline; the cuff was inflated 40 mmHg above the systolic, blocking flow for 5 minutes (ischemia), then it was released (post-ischemia). The BAD increase <11% at one-minute post-ischemia signified probable ED, confirmed if BAD ≥11% post-sublingual nitroglycerin. We took thermographic photographs (FLIR One PRO thermal imaging camera, Android Camera) per minute: baseline, 1,2,3,4,5 (ischemia), 1,2,3 (post-ischemia) in the palmar region. We perform descriptive statistics, ROC curve, Mann-Whitney U test, chi-square, or Fisher's exact
We included 38 subjects (28 women, 10 men), age 50 (IQR-34.8, 58.3) years. Nine had ED (FMV 2.5%; IQR-8.3,5.1). The best cut-off point for normal endothelial function in subjects with cardiovascular risk factors was ≥36°C at one minute of ischemia; sensitivity 85%, specificity 70%, positive and negative predictive values of 78 and 77%, AUC 0.796 95%CI (0.598-0.995), LR+ 2.82 95%CI (1.06-7.48), LR- 0.22 95%CI (0.06-0.84).