Respiratory motion in coronary magnetic resonance angiography: A comparison of different motion models

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Abstract
Purpose To assess respiratory motion models for coronary magnetic resonance angiography (CMRA). In this study various motion models that describe the respiration‐induced 3D displacements and deformations of the main coronary arteries were compared. Materials and Methods Multiple high‐resolution 3D coronary MR images were acquired in healthy volunteers using navigator‐based respiratory gating, each depicting the coronary vessels at different respiratory motion states. In the images representing the different inspiratory states the displacements and deformations of the main coronary vessels with respect to the end‐expiratory state were determined, by means of elastic registration. Several correction models (superior‐inferior (SI) translation, 3D translation, and 3D affine transformation) were tested and compared with respect to their ability to map a selected inspiratory to the end‐expiratory motion state. Results 3D translation was found to be superior over SI translation, which is commonly used for prospective motion correction in CMRA. The 3D affine transformation was found to be the best correction model considered in this study. Furthermore, a large intersubject variability of the model parameters was observed. Conclusion The results of this study indicate that a patient‐adapted 3D correction model (3D translation or better 3D affine) will considerably improve prospective motion correction in CMRA. J. Magn. Reson. Imaging 2002;15:661–671.