Fine-scale motion detection using intrinsic list mode PET information

Motion during extended nuclear medicine scanning sequences can significantly degrade the quality of reconstructed images. Correction for this motion requires an accurate motion sensor. We describe a technique to detect motion in list mode positron emission tomography (PET) imagery that relies upon information from the list mode data stream itself. In studies where the tracer contrast to background contrast is high, the axial component of the center of mass (CM) for tomograph events can serve as an accurate indicator of motion. Because the method does not require reconstruction of images, it may be applied to motion detection at a very fine temporal scale. The technique has been applied to the detection of motion due to the respiratory cycle in cardiac PET imaging.