Motion Corrected Simultaneous Cardiac PET and Coronary MR Angiography with High Acquisition Efficiency

Abstract

Purpose: Develop a framework for efficient free-breathing simultaneous whole-heart coronary magnetic resonance angiography (CMRA) and cardiac positron emission tomography (PET) on a 3T PET-MR system. Methods: An acquisition that enables non-rigid motion correction of both CMRA and PET has been developed. The proposed method estimates translational motion from low-resolution 2D MR image-navigators acquired at each heartbeat, and 3D non-rigid respiratory motion between different respiratory bins from the CMRA data itself. Estimated motion is used for correcting the CMRA as well as the emission and attenuation PET datasets to the same respiratory position. The CMRA approach was studied in ten healthy subjects and compared for both left and right coronary arteries (LCA, RCA) against a reference scan with diaphragmatic navigator gating and tracking. The PET-CMRA approach was tested in five oncology patients with 18F-FDG myocardial uptake. PET images were compared against uncorrected and gated PET reconstructions. Results: For the healthy subjects, no statistically significant differences in vessel length and sharpness (P>0.01) were observed between the proposed approach and the reference acquisition with navigator gating and tracking although data acquisition was significantly shorter. The proposed approach improved CMRA vessel sharpness by 37.9%, 49.1% (LCA, RCA) and vessel length by 48.0%, 36.7% (LCA, RCA) in comparison with no motion correction for all the subjects. Motion-corrected PET images showed improved sharpness of the myocardium compared to uncorrected reconstructions and reduced noise compared to gated reconstructions. Conclusion: Feasibility of a new respiratory motion compensated simultaneous cardiac PET-CMRA acquisition has been demonstrated.