Fig. 5

Interquartile range (IQR) relative to the 75th percentile of the voxel intensity in the reference region according to correctness of SUSI-based and SBR-based classification of the PPMI FP-CIT images as PD or HC (“correct” = true positive or true negative, “incorrect” = false positive or false negative). The relative IQR is as measure of the uncertainty of the estimate of the non-displaceable count density by the 75th percentile of the voxel intensity in the reference region