A 5D MRI Framework for Cardiac Motion Characterization in Radiation Therapy

Motivation: Current radiotherapy treatment planning does not account for cardiac substructure motion during the respiratory and cardiac cycle, thus leading to suboptimal treatment plans. Goal(s): To develop a free breathing 5D MRI framework to characterize cardiac and respiratory motion of the heart for use in radiotherapy treatment planning. Approach: A double gated (cardiac and respiratory) radial bSSFP acquisition and constrained reconstruction pipeline were implemented and motion and tested in five volunteers. Results: Left ventricle centroid analysis showed 5D images provided significant motion characterization. Advanced reconstruction allows <5 min scan time. Impact: The primary impact of this work will be on patients receiving thoracic radiotherapy. More accurate treatment planning and sparing of sensitive cardiac substructures will improve patient outcomes and reduce long term cardiotoxicities.