ECG-triggered NMR imaging of the heart.

The relatively long scan time needed for an NMR image gives rise to motion artifacts when imaging the heart. These can be strongly reduced by synchronizing the imaging sequences to the ECG (cardiac gating). Using an adjustable delay between the ECG pulse and the trigger pulse for the repeated imaging sequence, detailed heart images can be made in any phase of the cardiac cycle. Images made at systole and diastole in different planes can be used for the accurate assessment of left ventricular volume and ejection fraction. NMR imaging can provide heart images in any slice orientation without the use of contrast medium or obstruction from bones.