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Figure 1 Receiver operating characteristic curves with time domain (left panel) and spectral turbulence analysis (STA, right panel) parameters. The arrows point to the values selected as optimal cutoffs for each parameter. Note that the best balance between sensitivity and specificity is obtained with RMS40 (among time domain parameters) and spectral entropy (STA parameters). The opposite occurred with QRSD and ISCSD, which had a lower specificity than the other parameters over a wide range of sensitivity levels. Entropy = spectral entropy; ISCM = interslice correlation mean; ISCSD = interslice correlation standard deviation; LAS40 = duration of low amplitude signals <40 µV; LSCR = low slice correlation ratio; QRSD = total filtered QRS duration; RMS40 = root mean square voltage of the last 40 ms of the filtered QRS.