Navigator-echo-based real-time respiratory gating and triggering for reduction of respiration effects in three-dimensional coronary MR angiography.
OBJECTIVE
To test the hypothesis that respiration effects in three-dimensional (3D) coronary magnetic resonance (MR) imaging can be reduced with navigator-echo-based gating or triggering according to the superior-inferior position of the diaphragm.


METHODS
Real-time respiratory gating and respiratory triggering (breath hold with feedback) were implemented with navigator echoes in a magnetization-prepared, segmented, 3D coronary imaging sequence. The two techniques were first tested with a motion phantom. An imaging protocol that compared real-time respiratory-gated acquisition, real-time respiratory-triggered acquisition, and continuous acquisition was then evaluated in six healthy subjects.


RESULTS
Real-time respiratory-gated and respiratory-triggered acquisition were superior to continuous acquisition with two signals averaged (P = .025). The performance of the gated acquisition was about the same as that of the triggered acquisition (P = .05).


CONCLUSIONS
Navigator-echo-based, real-time respiratory-gating and respiratory-triggering techniques are practical methods for effective reduction of respiration effects in coronary MR imaging.
Department of Diagnostic Radiology, Mayo Clinic, Rochester, MN 55905, USA.
Y
Y
Wang
P J
PJ
Rossman
R C
RC
Grimm
S J
SJ
Riederer
R L
RL
Ehman
D000328:Adult; D016477:Artifacts; D003331:Coronary Vessels / Q000033:anatomy & histology*; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008875:Middle Aged; D019047:Phantoms, Imaging; D012119:Respiration