PET Motion Tracking with Radioactive Fiducial Markers

Anesthetics used to keep small animals during PET studies are a major confounding factor in the and retention of radiotracers, particularly in the brain. study proposes the use of radioactive fiducial markers to and recover motion using only data from the PET allowing anaesthetized imaging. Three small Na-22 fiducials (1mm, 10uCi) were attached to outside of a micro hot-rod cylinder. To measure the with which fiducial markers can be tracked in the presence of radioactive background the cylinder was filled with 1mCi F-18 and translated through the field of view at a known speed. further validation the cylinder was filled with 0.3mCi F-18 waved in a random motion path for 10 min. To process listmode data is first gated into short time frame (100ms) using simple ray casting. Each time frame image was (Mutual Information) to a reference frame to recover transforms. The listmode data is reprocessed transforming event and binning into a single motion corrected sinogram is reconstructed using standard programs. In the controlled motion study the fiducial markers tracked with high precision (mean abs. error=0.34mm). The motion recovered images were artifact free, good image quality, and a minimal loss of resolution. studies suggest that motion tracking with fiducials is possible, and is suitable to enable brain imaging in a rat.