Breath-hold three-dimensional true-FISP imaging of coronary arteries using asymmetric sampling.
OBJECTIVE
To evaluate the feasibility of using asymmetric sampling in a three-dimensional, magnetization-prepared, segmented true-FISP (fast imaging with steady-state precession) sequence in order to reduce the sensitivity to resonance offsets, while simultaneously improving imaging speed.


METHODS
Asymmetric sampling reduces the repetition time, leading to reduced resonance offset effects and improved resolution in a fixed imaging time. However, it introduces additional phase terms due to blood flow, which can cause image artifacts. Computer simulations were performed to study the off-resonance and flow effects of asymmetric sampling in true-FISP. Coronary artery imaging was performed in healthy volunteers.


RESULTS
Simulations and volunteer studies show that image artifacts due to flow-induced phase variations may be acceptable at low velocities. Volunteer studies demonstrate that relatively high-resolution coronary artery images can then be acquired within a single breath-hold with segmented three-dimensional true-FISP imaging using data asymmetry in the readout direction.


CONCLUSIONS
Asymmetric sampling is a useful modification to true-FISP for reducing the off-resonance artifacts and improving imaging speed when the flow velocities are small.
Deshpande
Vibhas S
VS
Department of Radiology, Northwestern University, Chicago, Illinois, USA.
Shea
Steven M
SM
Chung
Yiu Cho
YC
McCarthy
Richard M
RM
Finn
J Paul
JP
Li
Debiao
D
D000328:Adult; D003198:Computer Simulation; D003331:Coronary Vessels; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged