Figure legends
Figure 1. Images of the skin of patients with typical ColdU and a positive response to cold stimulation testing with an ice cube (A) and TempTest® (B).
Figure 2. Experimental setup: scheme (A), appearance (B) and running state (C).
Figure 3. Data processing pipeline.
PPG, photoplethysmogram
Figure 4A. Change in skin perfusion at sites of cold exposure is significantly higher in patients with typical ColdU as compared to patients with atypical ColdU and HCs
PPG, photoplethysmogram, CTT , critical temperature threshold, Standard CST , standard cold stimulation test,ColdU , cold urticaria, TempTest®,R PPG, ratio of post-provocation and baseline PPG amplitudes
Vertical bars indicate CTT values for patients with a positive ICT and TempTest® (pink) and with negative standard CSTs (cyan). For participants with a negative TempTest®, the bar height is shown as 1°C. Circles stand for the measured valueR PPG. R PPG varies between typical ColdU patients and HCs. By introducing a properR PPG threshold of 3 (black line) we may clearly distinguish participants with (red circles) and without (blue circles) positive reactions to standard CSTs.
Figure 4B illustrates the similarities (green) and differences (black) between our PPG-based technique and CST with and an ICT or TempTest®, in the same order.
Figure 5. ROC-curve of R PPG and CST
FN , false negative, FP , false positive, TN , true negative, TP, true positive.