Impact of spillover from white matter by partial volume effect on quantification of amyloid deposition with [¹¹C]PiB...

High non-specific uptake of [¹¹C]Pittsburgh compound B ([¹¹C]PiB) in white matter and signal spillover from white matter, due to partial volume effects, confound radioactivity measured in positron emission tomography (PET) with [¹¹C]PiB. We aimed to reveal the partial volume effect in absolute values of kinetic parameters for [¹¹C]PiB, in terms of spillover from white matter. Dynamic data acquired in [¹¹C]PiB PET scans with five healthy volunteers and eight patients with Alzheimer's disease were corrected with region-based and voxel-based partial volume corrections. Binding potential (BP_ND) was estimated using the two-tissue compartment model analysis with a plasma input function. Partial volume corrections significantly decreased cortical BP_ND values. The degree of decrease in healthy volunteers (-52.7±5.8%) was larger than that in Alzheimer's disease patients (-11.9±4.2%). The simulation demonstrated that white matter spillover signals due to the partial volume effect resulted in an overestimation of cortical BP_ND, with a greater degree of overestimation for lower BP_ND values. Thus, an overestimation due to partial volume effects is more severe in healthy volunteers than in Alzheimer's disease patients. Partial volume corrections may be useful for accurately quantifying Aβ deposition in cortical regions.