Figure 1.

Imaging of early Parkinson’s disease. A: MRI of the striatum does not indicate any significant anatomical abnormalities; B: PET reveals selective regional alterations in diverse neurochemical processes: FDG PET shows putaminal hypermetabolism relative to the caudate (approximately 10%); C: [¹⁸F]fluoroethylspiperone PET shows approximately 15% greater D₂ receptor density in the putamen as compared to the caudate; D: FDOPA PET shows significant reduction in dopamine synthetic capacity (80%) in the putamen but not in the caudate. Arrows in B, C, and D indicate putamen. MRI: Magnetic resonance imaging; PET: Positron emission tomography; FDG: 2-[¹⁸F]-fluoro-2-deoxy-D-glucose; FDOPA: [¹⁸F]-labeled L-3,4-dihydroxiphenylalanine. (Originally published in the JNM. Phelps ME. PET: the merging of biology and imaging into molecular imaging. J Nucl Med 2000; 41: 661-681. © by the Society of Nuclear Medicine and Molecular Imaging, Inc.)