Comprehensive Motion Correction for Cardiac PET Imaging

Cardiac imaging in PET is susceptible to image degradation from multiple types of motion: myocardial motion due to the cardiac cycle, respiratory motion (which can vary greatly over the course of a scan), and bulk body movements. A comprehensive approach to cardiac motion correction has been developed which addresses each of these types of motion. First, the effect of respiratory motion and bulk body movements on the myocardium is modelled as rigid translation motion; these translations are estimated in image space from short-duration (0.5 s) frames reconstructed over the full duration of the scan. This accounts for variation in respiratory motion because no periodicity is assumed. Next, an ECG signal is used for phase-based gating of the myocardial cycle. The cardiac gated reconstructions incorporate event-by-event motion correction from the estimated translations. The resulting cardiac gated series presents the heart at a fixed position, with only cardiac motion between gates. Finally, the cardiac gated images are combined into a single volume via non-rigid registration using the Q.Freeze2 package from GE HealthCare. This approach provides a single fully motion-corrected, quantitative image of the myocardium that utilizes all counts. Results from this approach are shown on NH 3 data with the reconstructions showing improved contrast and signal-to-noise.