MR angiography with a cardiac-phase--specific acquisition window.
A method for cardiac-phase-specific magnetic resonance (MR) angiography is presented. An electronics module permits incrementing of phase-encoding gradients and storage of incoming data only during a chosen portion of the cardiac cycle. Suppression of stationary material is maintained by delivering radio-frequency pulses at constant TR throughout the cycle. Imaging of a pulsatile flow phantom demonstrates that acquiring data only during systole substantially increases the signal intensity of flowing material. In addition, phase-encoding ghost artifacts are eliminated from the neighborhood of the vessel. Image acquisition time is minimized by acquiring only the low-frequency phase-encoding lines in the cardiac-phase-specific mode. In healthy volunteers, greatly improved MR angiograms of the lower extremities are obtained. Fat saturation and magnetization transfer further enhance vessel/background contrast. Acquiring data only during systole ensures rapid inflow for all phase-encoding lines, permitting a near-longitudinal section orientation without in-plane saturation. This substantially reduces total acquisition time relative to axial acquisition.
Selby
K
K
Department of Radiology, University of California, San Francisco.
Saloner
D
D
Anderson
C M
CM
Chien
D
D
Lee
R E
RE
D001808:Blood Vessels / Q000033:anatomy & histology*; D006801:Humans; D007866:Leg / Q000098:blood supply; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural; D011673:Pulsatile Flow; D013599:Systole