Figure 2.

Specific binding ratio (SBR) to non-SBRs imaging. The above formula SBR(x, y) is calculated for whole-brain regions. At this time, if the SBR value is negative, it will be replaced with 0, and if it is positive, it will be that value. S₁₂₈ represents the single-photon emission computed tomography (SPECT) value in the striatum and brain stem, and B₁₂₈ represents the SPECT value in the occipital-lobe region with no specific binding to dopamine transporter and SERTs. When measuring B₁₂₈, a region of interest (ROI) is set to three-dimensionally enclose the entire occipital-lobe region, and within that ROI, voxel-wise averages are calculated for imaging