Motion artifact reduction and vessel enhancement for free-breathing navigator-gated coronary MRA using 3D k-space reordering

Breathing-induced bulk motion of the myocardium during data acquisition may cause severe image artifacts in coronary magnetic resonance angiography (M RA). Current motion compensation strategies include breath-holding or free- breathing MR navigator gating and tracking techniques. Navigator-based tech niques have been further refined by the applications of sophisticated 2D k- space reordering techniques. A further improvement in image quality and a r eduction of relative scanning duration may be expected from a 3D k-space re ordering scheme. Therefore, a 3D k-space reordered acquisition scheme inclu ding a 3D navigator gated and corrected segmented k-space gradient echo ima ging sequence for coronary MRA was implemented. This new zonal motion-adapt ed acquisition and reordering technique (ZMART) was developed on the basis of a numerical simulation of the Bloch equations. The technique was impleme nted on a commercial 1.5T MR system, and first phantom and in vivo experime nts were performed. Consistent with the results of the theoretical findings , the results obtained in the phantom studies demonstrate a significant red uction of motion artifacts when compared to conventional (non-k-space reord ered) gating techniques. Preliminary in vivo findings also compare favorabl y with the phantom experiments and theoretical considerations. Magn Reson M ed 46:645-652, 2001. (C) 2001 Wiley-Liss, Inc.