MRI employs inherent physiologic properties of tissues to create images of body structures. This technique provides a wide field of view for assessing structures within the thoracic cage, specifically for cardiac imaging. The ability to orient images in multiple planes and off-axis planes is key to the technique’s diagnostic utility and allows images to be oriented within specific oblique or perpendicular views for careful inspection of cardiac structures and/or the great vessels. Additionally, gating or triggering of the MRI scanner based on the R wave of the patient’s ECG for each cardiac cycle allows stop-frame imaging of the heart and great vessels. The inherent characteristics of flowing blood result in contrast enhancement of vascular structures without the administration of iodinated contrast agents. Major uses include the assessment of congenital heart disease (adult and pediatric), intracardiac structures, and the great vessels.
Unlike other imaging modalities, such as CT or planar blood pool imaging, MRI provides three-dimensional assessment of myocardial structures. Its advantages, including image resolution and field of view, outweigh some of its limitations, such as placing the patient within a closed area, potential difficulties with cardiac gating, and increased cost.