Abstract:
HTML
Purpose: Currently the electrocardiogram (ECG) is used to gate coronary magnetic resonance (MR) data acquisitions, but substantial motion can occur under ECG guidance. The purpose of the present study is to measure the 3D motion of the coronary arteries during the cardiac cycle using the novel cardiac fat navigator echoes.
Methods and Materials: The cardiac fat navigator echo was acquired by using spatial saturation pulses to suppress the chest wall signal and 2D binomial spatial-spectral pulses to excite the epicardial fat that surrounds and moves together with the proximal coronary arteries. The excited fat signal was sampled along kx, ky and kz axes to detect 3D bulk translation. Experiments were performed on 5 healthy subjects using a 1.5T MR scanner. Cardiac fat navigator echo was sampled every 42 ms in a 20 heartbeat breath-hold. The ECG signal was recorded simultaneously with the navigator acquisition using an oscilloscope. The gradient switching in the navigator sequence caused spikes in the observed ECG, which were used to co-register the navigator and the ECG signal in time. Displacements were extracted from navigator data using a least-squares-based algorithm, and velocities were computed from the displacement time courses.
Results: The displacement and velocity time courses from all subjects demonstrated two rest periods (velocities in all three directions < 25 mm/s), [delay from QRS 324±45 ms, duration 80±38 ms] (late systole), [605±46 ms, 164±94 ms] (mid-diastole). The R-R intervals were 967±110 ms. There were positive peak velocities (ventricular contraction) prior to late systole, negative peak velocities (atrial filling) prior to mid-diastole but after systole, and negative peak velocities (atrial contraction) at end-diastole.±±
Conclusion: The cardiac fat navigator echo provides a direct measure of coronary motion and may replace the ECG signal as a more effective guide to suppress motion artifacts in cardiac MRI.
Questions about this event email: thanh@mrctr.upmc.edu
Nguyen PhD, T,
Direct Measurement of Coronary Artery Motion Using Cardiac Fat Navigator Echoes. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3107501.html
