RT Journal Article
SR Electronic
T1 Longitudinal Tau PET Using <sup>18</sup>F-Flortaucipir: The Effect of Relative Cerebral Blood Flow on Quantitative and Semiquantitative Parameters
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 281
OP 286
DO 10.2967/jnumed.122.263926
VO 64
IS 2
A1 Visser, Denise
A1 Tuncel, Hayel
A1 Ossenkoppele, Rik
A1 Yaqub, Maqsood
A1 Wolters, Emma E.
A1 Timmers, Tessa
A1 Weltings, Emma
A1 Coomans, Emma M.
A1 den Hollander, Marijke E.
A1 van der Flier, Wiesje M.
A1 van Berckel, Bart N.M.
A1 Golla, Sandeep S.V.
YR 2023
UL http://jnm.snmjournals.org/content/64/2/281.abstract
AB Semiquantitative PET measures such as SUV ratio (SUVr) have several advantages over quantitative measures, such as practical applicability and relative computational simplicity. However, SUVr may potentially be affected by changes in blood flow, whereas quantitative measures such as nondisplaceable binding potential (BPND) are not. For 18F-flortaucipir PET, the sensitivity of SUVr for changes in blood flow is currently unknown. Therefore, we compared semiquantitative (SUVr) and quantitative (BPND) parameters of longitudinal 18F-flortaucipir PET scans and assessed their vulnerability to changes in blood flow. Methods: Subjects with subjective cognitive decline (n = 38) and Alzheimer disease patients (n = 24) underwent baseline and 2-y follow-up dynamic 18F-flortaucipir PET scans. BPND and relative tracer delivery were estimated using receptor parametric mapping, and SUVr at 80–100 min was calculated. Regional SUVrs were compared with corresponding distribution volume ratio (BPND + 1) using paired t tests. Additionally, simulations were performed to model effects of larger flow changes in different binding categories. Results: Results in subjective cognitive decline and Alzheimer disease showed only minor differences between SUVr and BPND changes over time. Relative tracer delivery changes were small in all groups. Simulations illustrated a variable bias for SUVr depending on the amount of binding. Conclusion: SUVr provided an accurate estimate of changes in specific binding for 18F-flortaucipir over a 2-y follow-up during which changes in flow were small. Notwithstanding, simulations showed that large(r) flow changes may affect 18F-flortaucipir SUVr. Given that it is currently unknown to what order of magnitude pharmacotherapeutic interventions may induce changes in cerebral blood flow, caution may be warranted when changes in flow are potentially large(r), as in clinical trials.