Magnetic resonance imaging assessment of left ventricular function and wall motion

Assessment of left ventricular (LV) function is essential for the diagnosis and treatment of cardiac patients. A reliable and noninvasive tool for quantifying global and local LV function is needed. Magnetic resonance (MR) imaging has several unique features that are well suited to clinical examinations: it is noninvasive, does not expose the patient to ionizing radiation, and provides images of high spatial resolution and excellent soft tissue contrast without the need for contrast medium injection. In this paper, I review the reported evidence concerning the validity of MR imaging assessment of LV volume, including end-diastolic volume, end-systolic volume, and ejection fraction, and the validity of using MR imaging to monitor LV wall motion. Abundant evidence from phantom, animal, and human studies supports that MR imaging provides accurate and reproducible information that is substantially superior to that from conventional modalities such as angiographic ventriculography, radionuclide scintigraphy, and echocardiography. A fast MR imaging technique, cine MR imaging, further enhances the clinical feasibility of MR imaging by reducing the scanning time to about 20 minutes. Today, cine MR imaging is widely accepted as a reliable clinical tool. It may be considered an in vivo standard for quantification of LV volume and wall motion. Faster MR imaging techniques, such as TurboFLASH and echo-planar imaging, decrease the examination time to several seconds. This allows evaluation of transient functional changes during pharmacologically or physically induced stress tests.