Movement correction of [18F]FDDNP PET studies for brain amyloid imaging

2-(l-{6-[(2-[18F]fluoroethyl)(methyl)amino]-2-naph- thyl}ethylidene)malononitrile ([18F]FDDNP) PET studies for imaging neuronal concentration of beta-amyloid plaques and neurofibrillary tangles, the neuropathological hallmarks of Alzheimer's disease (AD), usually requires a 1-2 hour dynamic scan to measure the kinetics of the tracer in brain tissue. It is difficult for the subject to keep his or her head stationary during the entire data acquisition period. Thus, the reliability of the acquired kinetic data could be severely compromised. Furthermore, misalignment between transmission (TX) and emission (EM) scans due to head movement could introduce errors in attenuation correction (AC) and physiological parameters. In this study, we have developed an image-based procedure for head movement correction that takes a TX image and coregisters it to its corresponding non-AC EM frame before reconstruction of the dynamic image and then realigns all the now proper AC EM frames to a common reference frame. Effects of head movement on tracer time-activity curves and distribution volume ratio (DVR) parametric images are also investigated. The proposed movement correction procedure is done with [18F]FDDNP as a case in point but has the potential to be used in a wide variety of dynamic brain PET studies.