Longitudinal [¹⁸F]flortaucipir PET: Comparison of quantitative and semi‐quantitative parameters

Abstract Background Dynamic [ 18 F]flortaucipir PET imaging allows for more accurate quantification of specific binding compared to static in Alzheimer’s disease (AD). Besides, with dynamic flow is taken into account, which especially important longitudinal studies, because progression or drug intervention may lead changes. We aimed compare semi‐quantitative (SUVr) and quantitative (BP ND ) parameters a study. Method included subjects subjective cognitive decline (SCD; n=38) AD patients (n=24). All underwent baseline (BL) 2‐year follow‐up (FU) PET. BP R 1 (relative cerebral blood flow) were calculated (RPM; reference region cerebellar gray). SUVr was derived 80‐100 min p.i.. (Trans)entorhinal, limbic neocortical regions‐of‐interest (ROIs) assessed. For each parameter %change (100*(FU‐BL)/BL). Regional against respective DVR +1) using paired T‐tests. Additionally, simulations performed model effects changes on high, medium low categories. category, values varied mimic 5‐25% increase decrease flow. Thereafter, %bias respect underlying its association change evaluated. Result In SCD, there significant difference between (2.56%) (1.85%) the (trans)entorhinal ROI (p<0.05) only. AD, differences found (DVR 6.61% vs. 7.52%; p<0.05) small (+0.7% SCD ‐1.6% AD). Simulations showed varying depending binding. With increasing decreased bias conditions observed, whereas high an increased seen. remained relatively stable under different conditions, irrespective Conclusion Compared , provided good estimate over two‐year follow‐up. However, that subject variable case larger changes, seemed be tau load. Therefore, should preferred SUVr, context pharmacotherapeutic interventions could induce