Figure 1. Representative surface maps of Pittsburgh compound B (PiB) distribution volume ratio (DVR) in Parkinson disease (PD).

Shown are surface projection representations of ¹¹C-PiB DVRs in representative subjects with PD (rows). Images are in pseudocolor according to the key at the bottom right, ranging from a minimum DVR of 0 to a maximum DVR of 3. The top 2 rows depict subjects classified as having mild dementia (DEM) after neuropsychometric evaluation. The next 2 rows depict subjects classified as having mild cognitive impairment (MCI). The bottom row depicts a subject with normal-range neuropsychological abilities (NML). Subjects in the top 3 rows were classified as PiB-positive by qualitative assessment of these projection images as well as in transaxial assessments of frontal cortical/subcortical white matter PiB DVR. Note a similar pattern of regional cortical PiB DVRs, with the most conspicuous elevations above cerebellar background in the frontal and temporal lobes and in the posterior cingulate cortex. This pattern may also be present, albeit at low intensity, even in the subjects classified as PiB-negative in the bottom 2 rows.