Cardiac function by magnetic resonance imaging

Abstract

Gated magnetic resonance imaging of the heart displays cardiac structures with excellent resolution. This ability should be useful for assessment of cardiac physiology where acquisition of systolic and diastolic images is required. In this study, left ventricular ejection fraction was determined in 50 patients from oblique long axis views of the left ventricle using the area length formula. Angulated views were obtained by electronic gradient angulation. For comparison, all patients had monoplane angiocardiography in the RAO position. Forty-five patients were also studied by radionuclide ventriculography. Ejection fractions determined by MRI and angiocardiography were closely correlated (r = 0.90). Correlation between MRI and radionuclide ventriculography was also acceptable (r = 0.79). In addition to global left ventricular function, MR images provide information about regional wall motion. In order to acquire a three-dimensional set of images at various phases of the cardiac cycle, shorter imaging times are mandatory. A new imaging technique with potential for functional studies uses low flip angles, short repetition times and gradient refocused echoes. Up to 40 images can be obtained within one cardiac cycle. When displayed in a looped fashion, visual assessment of cardiac motion, intracardiac blood flow, and systolic wall thickening is possible. Potential advantages of functional studies by MRI are the concomitant acquisition of anatomical information and the three dimensional frame of reference.

Comparison of cardiac volumetry using real-time MRI during free-breathing with standard cine MRI during breath-hold in children

“…The importance of cardiac magnetic resonance imaging (MRI) in pediatric cardiology as a noninvasive diagnostic method has increased substantially over the last few years. Cardiac MRI permits the flexible choice of imaging planes [ 1 ] that is relevant for the anatomical presentation of the heart and the quantification of functional parameters, such as ventricular volumetry [ 2 – 4 ]. Nevertheless, balanced standard steady-state free precession (bSSFP) cine MRI is associated with some disadvantages, such as the occasional need for data interpolation to display a heartbeat due to a low temporal resolution and the need for repetitive breath-hold maneuvers to achieve high image quality.…”

New Digital Measurement Methods for Left Ventricular Volume Using Real-time Three-dimensional Echocardiography: Comparison with Electromagnetic Flow Method and Magnetic Resonance Imaging

“…Accurate evaluation of left ventricular (LV) volume and ejection fraction (EF) has important diagnostic, prognostic and therapeutic implications; therefore, a rapid, accurate, reproducible and non-invasive method of calculating these indices is important [1,2] . While magnetic resonance imaging (MRI) is an accepted method for determining LV volume and EF [3,4] , the equipment is expensive, not mobile, and requires special facilities.…”