Visual analysis showed 86% sensitivity and 100-88% specificity for the differential diagnosis of primary PS from non-primary PS. Semiquantitative analysis showed a gradual hypo-uptake proportional to the disease severity obtained in the visual analysis. Semiquantitative analysis did not provide any additional information to the visual analysis. Intraclass correlation coefficient and Kappa statistics showed 0.92 and 0.80 values, respectively. The Cut-off value to differentiate primary PS from non-primary PS was 1.9 on the putamen index.