Striatal volumes. Mice (n = 5) received 1.12 ± 0.08 MBq/g b.wt. of 123I-β-CIT. They were imaged 4 h postinjection, and scanning length was 25 min (angular step 15°, 24 projections, 250 s per gantry position). The data were acquired in a 128 × 128 matrix with pixel size and a slice thickness of 0.2 mm. The anatomical volume of the striatum was estimated by several thresholds from the maximum intensity of the structure. A striatal volume was measured for the template and individual mice by choosing a threshold of 50% of the maximum intensity of the striatum (vertical line), which resulted as a striatal volume of 22.3 mm3 and 17.2 mm3 ± 20%, respectively.