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).

本数据库为一项诊断试验类研究的成果，研究于基线状态下测量肱动脉直径（Brachial Arterial Diameter, BAD）：将袖带充气至收缩压水平以上40mmHg，阻断血流5分钟（缺血状态），随后释放袖带进入缺血后阶段。若缺血后1分钟时肱动脉直径增幅<11%，则提示可能存在勃起功能障碍（Erectile Dysfunction, ED）；当舌下含服硝酸甘油后肱动脉直径增幅≥11%时，可确诊该病症。
研究人员使用FLIR One PRO热成像相机与安卓设备摄像头，于掌侧区域按1分钟间隔拍摄热成像照片，时间点分别为基线、缺血阶段的1、2、3、4、5分钟，以及缺血后阶段的1、2、3分钟。
本研究采用描述性统计、受试者工作特征曲线（Receiver Operating Characteristic, ROC）、曼-惠特尼U检验、卡方检验或费希尔精确检验开展数据分析。
本研究共纳入38名受试者，其中女性28名、男性10名，年龄中位数为50岁，四分位间距（Interquartile Range, IQR）为34.8~58.3岁。其中9名受试者罹患ED，频率加权中位数（Frequency Median Value, FMV）为2.5%，四分位间距为8.3~5.1。
针对合并心血管危险因素的受试者，其正常内皮功能的最佳截断值为缺血1分钟时体表温度≥36℃：灵敏度85%，特异度70%，阳性预测值与阴性预测值分别为78%与77%，曲线下面积（Area Under Curve, AUC）为0.796，95%置信区间为0.598~0.995；阳性似然比（Positive Likelihood Ratio, LR+）为2.82，95%置信区间为1.06~7.48；阴性似然比（Negative Likelihood Ratio, LR-）为0.22，95%置信区间为0.06~0.84。