Event-by-event motion compensation for small animal PET

In small animal PET imaging anaesthesia is usually required to eliminate motion. However, both anaesthesia and the alternative of forcibly restraining the animal, can disturb the very biochemical pathways that are of most interest in the brain. The ability to image the awake animal would represent a major advance. To this end we have investigated a motion correction technique suitable for small animal imaging on the microPET scanner, based on previous successful work in human brain PET. The efficacy of our technique was assessed on the microPET system by applying movements to a micro hot rod phantomduring list mode acquisition. Movements of the phantom in scanner coordinates were obtained using a commercially available optical motion tracking system operating in the visible spectrum. Motion correction, applied as corrective spatial transformations to individual lines of response, significantly reduced motion distortion. Our immediate goal is to perfect practical methods for marker attachment and motion tracking of small animals during microPET scans.