PARTIAL VOLUME CORRECTION TECHNIQUES FOR LONGITUDINAL TAU‐PET QUANTIFICATION: A COMPARISON STUDY

Abstract

AbstractBackgroundThe selection of an appropriate Partial Volume Correction (PVC) is crucial for evaluating tau accumulation rates using 18F‐Flortaucipir (18F‐FTP). PVC can reduce the impact of off‐target binding, but it can also increase noise and variability. While these effects may be averaged on cross‐sectional studies, they might be of paramount importance when evaluating within‐subject longitudinal tau‐PET signal. The aim of this study is to evaluate the robustness of different PVCs for the evaluation of tau accumulation rates in longitudinal 18F‐FTP studies, as measured by their correlation with cognitive clinical progression.Method111 cognitively impaired subjects from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) with serial 18F‐FTP PET and T1 images, as well as cognitive performance evaluation available for a 2‐year follow‐up period, were included in the study. 18F‐FTP PET images were corrected by applying a traditional deconvolution PVC (Grey matter only), the reblurred Van‐Cittert (RVC) analytical PVC (grey + white matter), and 2 voxel‐based PVCs, the region‐based voxel‐wise correction (RBV) and the iterative Yang (iY). Longitudinal rates of change for the regional standard uptake value ratios (SUVR) of the temporal meta‐ROI were computed for the images corrected for the different PVCs, and their correlation with the rates of change of the ADAS‐Cog 11 cognitive performance metric was analyzed.ResultThe deconvolution PVC correction showed the strongest correlation between decreased cognitive performance and increased tau accumulation rates (p<0.001, ρ = 0.38), followed closely by the RBV (p<0.001, ρ = 0.36) and iY (p<0.001, ρ = 0.35) corrections (Fig. 1). In contrast, the RVC results (p = 0.03, ρ = 0.20) were comparable to not applying any PVC at all (p = 0.03, ρ = 0.21).ConclusionOur findings suggest that longitudinal FTP studies might benefit from the use of PVC techniques for the evaluation of tau accumulation rates. Tau uptake rates of change tracked the observed clinical progression more accurately after certain PVC corrections were applied. Moreover, a simple deconvolution PVC has been shown to perform similarly to more complex, voxel‐wise corrections such as the RBV and iY.