RT Journal Article
SR Electronic
T1 Dynamic Amyloid PET: Relationships to Flortaucipir Tau PET Measures
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.120.254490
DO 10.2967/jnumed.120.254490
A1 Fabio Raman
A1 Yu-Hua Dean Fang
A1 Sameera Grandhi
A1 Charles F. Murchison
A1 Richard E. Kennedy
A1 John C. Morris
A1 Parinaz Massoumzadeh
A1 Tammie Benzinger
A1 Erik D. Roberson
A1 Jonathan McConathy
YR 2021
UL http://jnm.snmjournals.org/content/early/2021/05/27/jnumed.120.254490.abstract
AB Rationale: Measuring amyloid and predicting tau status using a single amyloid positron emission tomography (PET) study would be valuable for assessing brain AD pathophysiology. We hypothesized that early-frame amyloid PET (efAP) correlates with the presence of tau pathology because the initial regional brain concentrations of radioactivity are primarily determined by blood flow, which is expected to be decreased in the setting of tau pathology. Methods: 120 participants (63 amyloid-positive/57 amyloid-negative) with dynamic 18F-florbetapir-PET and static 18F-flortaucipir-PET scans obtained within 6 months of each other were included. These subjects were predominantly cognitively intact in both the amyloid positive (63%) and amyloid negative (93%) groups. Parameters for efAP quantification were optimized for stratification of tau PET positivity, assessed by either a tauopathy score or Braak regions. The ability of efAP to stratify tau positivity was measured using receiver operating characteristics (ROC) analysis of area under the curve (AUC). Pearson’s r and Spearman’s ρ were used for parametric and non-parametric comparisons between efAP and tau PET, respectively. Standardized net benefit was used to evaluate improvement in utilizing efAP as an additional co-predictor over hippocampal volumes in predicting tau PET positivity. Results: Measuring efAP within the hippocampus and summing the first 3 minutes of brain activity post-injection showed the strongest discriminative ability to stratify for tau positivity (AUC 0.67-0.89 across tau PET Braak regions) in amyloid positive individuals. Hippocampal efAP correlated significantly with a global tau-PET tauopathy score in amyloid-positive participants (r = -0.57, P < 0.0001). Compared to hippocampal volumes, hippocampal efAP showed stronger association with tau PET Braak stage (ρ = -0.58 vs. -0.37) and superior stratification of tau PET tauopathy score (AUC: 0.86 vs. 0.66, P = 0.002). Conclusion: Hippocampal efAP can provide additional information to conventional amyloid-PET, including estimation of the likelihood of tau positivity in amyloid-positive individuals.