Validation of the reference tissue model for estimation of dopaminergic D2-like receptor binding with...

Positron emission tomography measurements of dopaminergic D2-like receptors may provide important insights into disorders such as Parkinson's disease, schizophrenia, dystonia and Tourette's syndrome. The positron emission tomography (PET) radioligand [18F](N-methyl)benperidol ([18F]NMB) has high affinity and selectivity for D2-like receptors and is not displaced by endogenous dopamine. The goal of this study is to evaluate the use of a graphical method utilizing a reference tissue region for [18F]-NMB PET analysis by comparisons to an explicit three-compartment tracer kinetic model and graphical method that use arterial blood measurements. We estimated binding potential (BP) in the caudate and putamen using all three methods in 16 humans and found that the three-compartment tracer kinetic method provided the highest BP estimates while the graphical method using a reference region yielded the lowest estimates (P<.0001 by repeated-measures ANOVA). However, the three methods yielded highly correlated BP estimates for the two regions of interest. We conclude that the graphical method using a reference region still provides a useful estimate of BP comparable to methods using arterial blood sampling, especially since the reference region method is less invasive and computationally more straightforward, thereby simplifying these measurements.