Magnetic resonance imaging (MRI) has evolved to become a viable tool for heart imaging. Unlike other imaging modalities, MRI provides detailed information about the type and severity of heart disease in order to help guide therapeutic decisions.
Respiratory and cardiac motion made early attempts at using MRI for cardiac applications impossible. But thanks to faster acquisition techniques and cardiac ECG gating, these are no longer a factor.
Today, cardiac MRI is an excellent tool to determine myocardial viability. It can assess the size and thickness of chambers within the heart to determine the extent and severity of valvular disease. By distinguishing between viable and abnormal myocardium that may have been replaced by fibrosis or scar tissue, MRI can also determine the extent of damage caused by a heart attack.
Many physicians rely on CT and CT angiography to diagnose and evaluate or rule out heart disease. However, despite CT’s accuracy at pinpointing blockages in the coronary arteries, it lacks the ability to differentiate healthy tissue from abnormal tissue within the heart. CT is also not capable of assessing myocardial viability and quantifying myocardial perfusion.
Functional cardiac CT imaging requires the injection of a contrast agent, and while small, the risk of a range of side-effects from the harsh, iodine-based contrast is a real concern. Furthermore, some coronary CT tests (such as CTA) can expose the patient to up to 12 mSv of radiation, which is as high as some nuclear imaging studies.
In addition to evaluating the anatomy and function of heart chambers and valves, we at Colorado Imaging Associates have found cardiac MRI to be useful for assessing cardiac masses and thrombi, pre-operative planning, and evaluating the impact of surgery—especially in patients with congenital heart disease.
MRI offers a comprehensive assessment of the aortic root complex and thoracic access sites in patients who cannot undergo a contrast-enhanced CTA, as well as provides excellent measurement of the size of the annulus, left ventricular outflow tract (LVOT) and aortic valve area when compared to transthoracic echocardiogram. It can also accurately assess the severity of aortic stenosis when there is a discrepancy between clinical findings and echocardiography, due to low flow, poor acoustic window or inability to perform a stress study.
– Stephen Humes, M.D.
Colorado Imaging Associates will be hosting a CME course on cardiac MRI at St. Anthony’s Hospital this fall, specific date and time TBD. If you are interested in attending or would like more information , please email Dr. Humes at s.humes@www.ciapc.com.