Improved cardiac gating at 3T with the “3D-QRS” method utilizing MRI-compatible 12-lead ECGs

Background Blood is rapidly ejected from the left ventricle during early systole, travels in the aortic arch perpendicular to the MRI’s main field, thus generating a Magnetohydrodynamic (MHD) voltage which is larger than the real ECG QRS complex in high field MRI. The MHD voltage (VMHD) is severally irregular in patients with arrhythmia, since arrhythmic ECG beats are interleaved between successive sinus rhythm (SR) beats. The VMHD overlay in ECG traces can result in intermittent QRS detection, leading to blurred images and longer scan times. Since accurate gating is essential for successful cardiac imaging, we developed a “3D-QRS” method for real-time detection of the QRS complex based on 12-lead ECG traces acquired inside the MRI. We validated this method at 3T in patients with Premature Ventricular Contractions (PVCs), Atrial Fibrillation (AF) and in an exercising athlete with time-varying heart rate.