Abstract
18F-AV-1451 is currently the most widely used of several experimental tau PET tracers. The objective of this study was to evaluate 18F-AV-1451 binding with full kinetic analysis using a metabolite corrected arterial input function, and to compare parameters derived from kinetic analysis with standardized uptake value ratio (SUVR) calculated over different imaging time intervals. Methods: 18F-AV-1451 PET brain imaging was completed in 16 subjects: 4 young healthy volunteers (YHV), 4 aged healthy volunteers (AHV) and 8 Alzheimer’s disease subjects (AD). Subjects were imaged for 3.5 hours, with arterial blood samples obtained throughout. PET data were analyzed using plasma and reference-tissue-based methods to estimate the distribution volume (VT), the binding potential (BPND) and SUVR. BPND and SUVR were calculated using cerebellar cortex as reference region and were compared across the different methods and across the three groups (YHV, AHV and AD). Results: AD demonstrated increased 18F-AV-1451 retention compared to HV based on both invasive and non-invasive analyses in cortical regions where paired helical filaments (PHF) tau accumulation is expected in AD. A correlation of R2>0.93 was found between BPND (130 min) and SUVR-1 at all time intervals. Cortical SUVR curves reached a relative plateau around 1.0-1.2 for YHV and AHV by ~50 min, but increased in AD by up to ~20% at 110-130 min and ~30% at 160-180min relative to 80-100min. VT (130 min) was lower by 30-35% in the YHV compared to AHV. Conclusion: Our data suggest that although 18F-AV-1451 SUVR curves do not reach a plateau and are still increasing in AD, an SUVR calculated over imaging window of 80-100 min (as currently used in clinical studies) provides estimates of PHF tau burden in good correlation with BPND, while SUVR sensitivity to regional cerebral blood changes needs further investigation.
- Copyright © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.