Figure 4
![Figure 4](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Falzrt96/MediaObjects/13195_2011_Article_75_Fig4_HTML.jpg)
Multi-tracer positron emission tomography concept to study pathological and functional processes in the brain. Multi-positron emission tomography tracer concept applied in drug trials combined with atrophy studies (magnetic resonance imaging (MRI)), cerebrospinal fluid (CSF) biomarkers and cognitive testing. 11C-PMP, acetylcholinesterase; 11C-PIB, amyloid; 11C-deprenyl, astrocytosis; 11C-nicotine, nicotinic receptors; 18F-FDG, 2-[18F]-fluoro-2-deoxy-D-glucose metabolism. Red, high activity; yellow, medium activity; blue, low activity.