Repeatability of parametric methods for [(18)F]florbetapir imaging in Alzheimer’s disease and healthy controls: A test–retest study

Accumulation of amyloid beta (Aβ) is one of the pathological hallmarks of Alzheimer’s disease (AD), which can be visualized using [(18)F]florbetapir positron emission tomography (PET). The aim of this study was to evaluate various parametric methods and to assess their test-retest (TRT) reliability. Two 90 min dynamic [(18)F]florbetapir PET scans, including arterial sampling, were acquired (n = 8 AD patient, n = 8 controls). The following parametric methods were used; (reference:cerebellum); Logan and spectral analysis (SA), receptor parametric mapping (RPM), simplified reference tissue model2 (SRTM2), reference Logan (rLogan) and standardized uptake value ratios (SUV(r(50–70))). BP(ND)+1, DVR, V(T) and SUVr were compared with corresponding estimates (V(T) or DVR) from the plasma input reversible two tissue compartmental (2T4k_V(B)) model with corresponding TRT values for 90-scan duration. RPM (r(2) = 0.92; slope = 0.91), Logan (r(2) = 0.95; slope = 0.84) and rLogan (r(2) = 0.94; slope = 0.88), and SRTM2 (r(2) = 0.91; slope = 0.83), SA (r(2) = 0.91; slope = 0.88), SUVr (r(2) = 0.84; slope = 1.16) correlated well with their 2T4k_V(B) counterparts. RPM (controls: 1%, AD: 3%), rLogan (controls: 1%, AD: 3%) and SUV(r(50–70)) (controls: 3%, AD: 8%) showed an excellent TRT reliability. In conclusion, most parametric methods showed excellent performance for [(18)F]florbetapir, but RPM and rLogan seem the methods of choice, combining the highest accuracy and best TRT reliability.