Infrared thermal imaging for the early diagnosis of herpes zoster

Objective To investigate the role of infrared thermal imaging technology in the early diagnosis of herpes zoster, and explore the improvement of diagnosis of herpes zoster. Methods We select 20 cases of suspected herpes zoster patients whose one side of the torso area had neuralgia symptoms without herpes, then recorded the patients' pain area of the infrared thermal imaging and VAS score and measure the temperature difference of the both sides of the symmetrical area. Patients appeared herpes or not were closely followed in two weeks so as to make a definitive diagnosis. The evaluation index in the diagnostic accuracy with ROC curve analysis. The temperature difference of symmetrical area ΔT and VAS were considered as examined variable. The justified outcome of whether appear herpes in two weeks was considered as status variable. We made ROC curve analysis, calculated the area under the ROC (AUC) and Youden index, and found cut-off value. Results During the follow-up of two weeks, the patients appeared herpes zoster of related area can be diagnosed (13/20). The ROC curve results showed that:in the temperature difference of the both sides symmetrical area measured by infrared thermal imaging, the area under the ROC curve was 0.912, cut-off value was 0.85℃ and Youden index was 0.702; In VAS score, the area under the ROC curve was 0.434, cut-off value was 2.5 and Youden index was 0.176. Conclusion For those herpes zoster patients who develop neuralgia symptoms but without herpes, the infrared thermal imaging technology has additional diagnostic value, and it is easy-to-use, noninvasive, non-radiant and worthwhile for spreading in clinical practice.