Test-retest repeatability of [18F]Flortaucipir PET in Alzheimer's disease and cognitively normal individuals

J Cereb Blood Flow Metab. 2020 Dec;40(12):2464-2474. doi: 10.1177/0271678X19879226. Epub 2019 Oct 1.


The aim of this study was to investigate the test-retest (TRT) repeatability of various parametric quantification methods for [18F]Flortaucipir positron emission tomography (PET). We included eight subjects with dementia or mild cognitive impairment due to Alzheimer's disease and six cognitively normal subjects. All underwent two 130-min dynamic [18F]Flortaucipir PET scans within 3 ± 1 weeks. Data were analyzed using reference region models receptor parametric mapping (RPM), simplified reference tissue method 2 (SRTM2) and reference logan (RLogan), as well as standardized uptake value ratios (SUVr, time intervals 40-60, 80-100 and 110-130 min post-injection) with cerebellar gray matter as reference region. We obtained distribution volume ratio or SUVr, first for all brain regions and then in three tau-specific regions-of-interest (ROIs). TRT repeatability (%) was defined as |retest-test|/(average (test + retest)) × 100. For all methods and across ROIs, TRT repeatability ranged from (median (IQR)) 0.84% (0.68-2.15) to 6.84% (2.99-11.50). TRT repeatability was good for all reference methods used, although semi-quantitative models (i.e. SUVr) performed marginally worse than quantitative models, for instance TRT repeatability of RPM: 1.98% (0.78-3.58) vs. SUVr80-100: 3.05% (1.28-5.52), p < 0.001. Furthermore, for SUVr80-100 and SUVr110-130, with higher average SUVr, more variation was observed. In conclusion, while TRT repeatability was good for all models used, quantitative methods performed slightly better than semi-quantitative methods.

Keywords: Alzheimer’s disease; [18F]Flortaucipir; parametric methods; test–retest repeatability.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alzheimer Disease / complications
  • Alzheimer Disease / diagnostic imaging
  • Alzheimer Disease / metabolism*
  • Amyloid beta-Peptides / metabolism
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Carbolines / metabolism*
  • Cognition / physiology
  • Cognitive Dysfunction / metabolism
  • Female
  • Gray Matter / metabolism
  • Humans
  • Male
  • Middle Aged
  • Neuropsychological Tests / standards
  • Positron-Emission Tomography / methods*
  • Radiopharmaceuticals / metabolism
  • Reproducibility of Results
  • tau Proteins / metabolism


  • Amyloid beta-Peptides
  • Carbolines
  • Radiopharmaceuticals
  • tau Proteins
  • 7-(6-fluoropyridin-3-yl)-5H-pyrido(4,3-b)indole