Parametric binding images of the TSPO ligand [18F]DPA-714.

Abstract

Fluorine-18 labelled N,N-diethyl-2-(2-[4-(2-fluoroethoxy)phenyl]-5,7-dimethylpyrazolo[1,5-α]pyrimidine-3-yl)acetamide (18F-DPA-714) is a radioligand for the 18-kDa translocator protein. The purpose of the present study was to identify the best method for generating quantitative parametric images of 18F-DPA-714 binding. METHODS: Ninety minutes dynamic 18F-DPA-714 positron emission tomography scans with full arterial sampling from 6 healthy subjects and 9 Alzheimer's disease (AD) patients were used. Plasma input based Logan graphical and spectral (SA) analyses were used to generate parametric volume of distribution (VT) images. Five versions of Ichise, reference Logan (RLogan) and two basis function implementations (Receptor Parametric Mapping, RPM; Simplified Reference Tissue Model2, SRTM2) of SRTM, all using grey matter cerebellum as reference region, were used to generate binding potential (BPND) images. RESULTS: Plasma input Logan (r2 = 0.99, slope = 0.88) and SA (r2 = 0.99, slope = 0.93) generated estimates of VT that correlated well with values obtained using non-linear regression. BPND values generated using SRTM2 (r2 = 0.83, slope = 0.95) and RLogan (r2 = 0.88, slope = 1.01) correlated well with non-linear regression based estimates. CONCLUSION: Both Logan and SA can be used to obtain quantitatively accurate VT images of 18F-DPA-714. In addition, SRTM2 and RLogan can provide accurate BPND images. These parametric images could be used for voxel based comparisons