One recent study showed an AUC of only 0.89 for the SBR of [18F]-FE-PE2I during the late equilibrium.20 The authors attributed this to the fact that the clinical diagnosis of PD was not confirmed at follow-up in four of the patients enrolled as PD, causing normal DAT binding values in the PD cohort. This evidence concerns the gene SLC6A3 and Parkinson disease.