Free-Running Time-Resolved 3D+time Cardiovascular MRI at 40 Hz in a One Minute Scan using Cartesian Sampling and CMR-MOTUS

Motivation: Free-running Time-Resolved 3D+time cardiovascular MRI is a challenging protocol due to heart and respiratory dynamics. Goal(s): We propose to extract the time-resolved motion in the acquisition using cartesian sampling at a very high temporal resolution (40Hz) and reduced scan time (about one minute). Approach: We used the CMR-MOTUS framework to reconstruct motion fields in a deformable mechanical phantom, healthy volunteer, and patient dataset. Results: Realistic motion fields were reconstructed at 40Hz. In the phantom study, the ejection fraction was correlated with reference values, and high DICE-scores were achieved. This framework could improve patient comfort and enhance clinical workflow by enabling shorter scan time. Impact: By extracting high-quality time-resolved 3D motion fields at a very high temporal resolution (40Hz), the entire acquisition can be leveraged in the image reconstruction, hence shorter scans. Additionally, time-resolved cardiovascular volumetric analysis is enabled i.e. time-propagating segmentations using motion fields.