RT Journal Article
SR Electronic
T1 Evaluation of Dosimetry, Quantitative Methods, and Test–Retest Variability of <sup>18</sup>F-PI-2620 PET for the Assessment of Tau Deposits in the Human Brain
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 920
OP 927
DO 10.2967/jnumed.119.236240
VO 61
IS 6
A1 Bullich, Santiago
A1 Barret, Olivier
A1 Constantinescu, Cristian
A1 Sandiego, Christine
A1 Mueller, Andre
A1 Berndt, Mathias
A1 Papin, Caroline
A1 Perrotin, Audrey
A1 Koglin, Norman
A1 Kroth, Heiko
A1 Pfeifer, Andrea
A1 Tamagnan, Gilles
A1 Madonia, Jennifer
A1 Seibyl, John P.
A1 Marek, Kenneth
A1 De Santi, Susan
A1 Dinkelborg, Ludger M.
A1 Stephens, Andrew W.
YR 2020
UL http://jnm.snmjournals.org/content/61/6/920.abstract
AB 18F-PI-2620 is a next-generation tau PET tracer that has demonstrated ability to image the spatial distribution of suspected tau pathology. The objective of this study was to assess the tracer biodistribution, dosimetry, and quantitative methods of 18F-PI-2620 in the human brain. Full kinetic modeling to quantify tau load was investigated. Noninvasive kinetic modeling and semiquantitative methods were evaluated against the full tracer kinetics. Finally, the reproducibility of PET measurements from test and retest scans was assessed. Methods: Three healthy controls (HCs) and 4 Alzheimer disease (AD) subjects underwent 2 dynamic PET scans, including arterial sampling. Distribution volume ratio (DVR) was estimated using full tracer kinetics (reversible 2-tissue-compartment [2TC] model and Logan graphical analysis [LGA]) and noninvasive kinetic models (noninvasive LGA [NI-LGA] and the multilinear reference tissue model [MRTM2]). SUV ratio (SUVR) was determined at different imaging windows after injection. The correlation between DVR and SUVR, effect size (Cohen’s d), and test–retest variability (TRV) were evaluated. Additionally, 6 HCs received 1 tracer administration and underwent whole-body PET for dosimetry calculation. Organ doses and the whole-body effective dose were calculated using OLINDA 2.0. Results: A strong correlation was found across different kinetic models (R2 &gt; 0.97) and between DVR(2TC) and SUVR between 30 and 90 min, with an R2 of more than 0.95. Secular equilibrium was reached at around 40 min after injection in most regions and subjects. TRV and effect size for SUVR across different regions were similar at 30–60 min (TRV, 3.8%; Cohen’s d, 3.80), 45–75 min (TRV, 4.3%; Cohen’s d, 3.77) and 60–90 min (TRV, 4.9%; Cohen’s d, 3.73) and increased at later time points. Elimination was via the hepatobiliary and urinary systems. The whole-body effective dose was 33.3 ± 2.1 μSv/MBq for an adult female and 33.1 ± 1.4 μSv/MBq for an adult male, with a 1.5-h urinary bladder voiding interval. Conclusion: 18F-PI-2620 exhibits fast kinetics, suitable dosimetry, and low TRV. DVR measured using the 2TC model with arterial sampling correlated strongly with DVR measured by NI-LGA, MRTM2, and SUVR. SUVR can be used for 18F-PI-2620 PET quantification of tau deposits, avoiding arterial blood sampling. Static 18F-PI-2620 PET scans between 45 and 75 min after injection provide excellent quantification accuracy, a large effect size, and low TRV.