Abstract Details

Title Head-to-head comparison of tau and amyloid PET visual reads for differential diagnosis: An international, multi-center study

Topic Aging and Dementia

Presentation(s) S20 - Aging and Dementia 2 (1:24 PM-1:36 PM)

Poster/Presentation
Number 003

Background The diagnostic performance of FTP-PET, recently approved by the FDA, has not been compared to amyloid PET in clinically relevant cohorts.

Objective To compare the diagnostic accuracy of tau ([¹⁸F]Flortaucipir [FTP]) and amyloid PET visual reads for distinguishing Alzheimer’s disease (AD) dementia and amyloid-positive mild cognitive impairment (MCI) from other neurodegenerative diseases and cognitively normal (CN) controls.

Design/Methods

661 participants underwent FTP and amyloid PET at UCSF, Lund University, or Gangnam Severance Hospital. Amyloid PET tracers were site-specific (UCSF, [¹¹C]PIB; Lund, [¹⁸F]Flutemetamol; Gangnam, [¹⁸F]Florbetaben). Three visual raters interpreted amyloid PET using tracer-specific criteria and FTP-PET using a method developed by Sonni et al. (2021). One visual rater also interpreted FTP-PET scans using the FDA-approved visual interpretation method. Amyloid and FTP-PET were read by each reader in separate, randomized batches. The majority interpretation of each scan as amyloid positive/negative and tau positive/negative was used in the primary analysis. Diagnostic performance of FTP and amyloid PET visual reads and kappa statistics for intra- and inter-rater reliability were calculated. FTP-PET visual read methods were compared using the kappa statistic and McNemar’s test.

Results Amyloid and FTP-PET visual reads had similar sensitivity (92.6%, 95%-confidence interval [88.7-95.9%], 92.2% [88.2-95.2%], respectively) and specificity (82.9% [78.9-86.5%], 78.2% [73.9-82.1%], respectively) for distinguishing AD and amyloid-positive MCI from all other dementias and CN controls. FTP-PET intra-rater reliability was κ=0.80-1.00 (p<0.0001), and inter-rater reliability between reader pairs ranged from κ=0.78-0.85 (p<0.0001). Amyloid PET intra-rater reliability was κ=0.97 (p<0.0001) for each reader, and inter-rater reliability between reader pairs ranged from κ=0.82-0.88 (p<0.0001). There was moderate agreement between FTP-PET visual read methods (κ=0.58), but they were statistically different (χ² = 17, p<0.0001) due to differences in interpretation of tracer retention in mesial and anterolateral temporal cortex.

Conclusions FTP and amyloid PET visual reads have similar diagnostic performance and high intra- and inter-rater reliability.

Authors/Disclosures
David N. Soleimani-Meigooni, MD (University of California, San Francisco) PRESENTER	Dr. Soleimani-Meigooni has nothing to disclose.
	No disclosure on file
	No disclosure on file
	No disclosure on file
Hanna Cho, MD, PhD (Gangnam Severance Hospital)	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Oskar Hansson	No disclosure on file
Gil D. Rabinovici, MD, FAAN (UCSF Memory & Aging Center)	Dr. Rabinovici has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Eli Lilly. Dr. Rabinovici has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Alector. Dr. Rabinovici has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Merck. Dr. Rabinovici has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Johnson & Joihnson. Dr. Rabinovici has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for JAMA Neurology. The institution of Dr. Rabinovici has received research support from NIH. The institution of Dr. Rabinovici has received research support from American College of Radiology. The institution of Dr. Rabinovici has received research support from Alzheimer's Association. The institution of Dr. Rabinovici has received research support from Rainwater Charitable Foundation. The institution of Dr. Rabinovici has received research support from Genentech. Dr. Rabinovici has received personal compensation in the range of $500-$4,999 for serving as a Topic Chair, Course Director and teacher with AAN. Dr. Rabinovici has received personal compensation in the range of $500-$4,999 for serving as a Grant reviewer with NIH. Dr. Rabinovici has received personal compensation in the range of $500-$4,999 for serving as a Invited speaker with ANA.