Fig. 6.

PET versus SPECT Bland–Altman plots. Same data as in Fig. 5 shown as Bland–Altman plots. Triangles represent patients with discrepancy between PET and SPECT reading. The purple area represent the mean difference with 95% confidence limits (C.I.), the green area represent the upper limit of agreement with 95% C.I., and the red area the lower limit of agreement. As expected PET show relative higher values for putamen SBR (left) for PET compared to SPECT with 95% of patients being within 50% difference. Putamen/caudate nucleus ratio (right) show similarly relatively higher values but the difference is smaller and within 35%