Cardiac magnetic resonance imaging:
Periodic changes of the cardiac chambers and ventricular walls were visualized and interpreted by an experienced observer blinded to echocardiographic findings and clinical information. The imaging was performed in the supine position on all subjects using a 1.5 T (Magnetom Symphony) or a 3 T (Magnetom Trio, both from Siemens Medical Solutions, Erlangen, Germany) whole-body clinical MRI system. All images were tracked for end-systolic and end-diastolic endocardial contours. Modified Simpson’s rule was used to determine RV volumes. Three electrodes positioned on the left anterior hemithorax and cardiac synchronization was acquired. Commercially accessible (Argus version 4.01, Syngo MR B 13, Siemens Medical Solutions, Erlangen, Germany) software accomplished an evaluation of images. A mid-ventricular axial view, a cine breath-hold vertical long axis, and a cine breath-hold horizontal long axis established cardiac short axis. During short end-expiratory breath-holds, the ventricles were imaged in 8 mm increments using adjacent short-axis slices from the base to apex while the basal short-axis slice was placed beyond the mitral valve plane. Long axis views verified the short-axis acquisitions for comprehensive coverage of ventricles.