Fig. 4

Mean accuracy (left column), sensitivity (middle column), and specificity (right column) of the putamen SBR z-score for identification of PD patients or patients with neurodegenerative PS as a function of the size of the normal database used to estimate mean and standard deviation of normal putamen SBR for transforming SBR values into z-scores (a PPMI sample, OSEM, AAL-SBR; b PPMI sample, OSEM, HV-SBR; c clinical sample, OSEM with resolution recovery, AAL-SBR; d clinical sample, OSEM with resolution recovery, HV-SBR; e clinical sample, filtered backprojection, AAL-SBR; f clinical sample, filtered backprojection, HV-SBR). SBR values were Ln-transformed prior to transforming them into z-scores in all settings. The error bars indicate the difference between mean accuracy, sensitivity, or specificity and the 5th percentile over the 10,000 randomly sampled normal databases. The dashed line represents the performance of the z-score of the putamen SBR when all HC subjects (n = 207) or all patients with non-neurodegenerative PS (n = 186) were used to estimate mean and standard deviation of normal putamen SBR for transforming SBR values into z-scores as benchmark