MRI for viewing the heart

MRI is a comprehensive method for examining the heart, wrote Constantin B. Marcu of the Hospital of Saint Raphael in New Haven, Conn., and colleagues in a review of cardiovascular MRI. In fact, the imaging technique can detect an enlarged heart and assess its function as well as visualize an aortic aneurysm and the thickening of the tissue surrounding the heart.

An MRI technique called delayed contrast enhancement can differentiate between dead and healthy heart tissue and show how much tissue damage has occurred after a heart attack. In addition, it can identify heart muscle inflammation in conditions such as sarcoidosis.

Another use for MRI is to complement echocardiography. Although echocardiography can show diseased heart valves, MRI is useful when echocardiographic images are blurry or when the results of echocardiography and cardiac catheterization conflict. Echocardiography can detect cardiac tumors, and MRI can further characterize their location and size.

Myocardial perfusion imaging and coronary angiography with MRI are relatively new procedures. MRI perfusion is as accurate as radionuclide imaging, but it does not expose patients to radiation and it takes place in one session, whereas radionuclide imaging requires two. As one multicenter clinical trial suggested, coronary MRI angiography can detect unusual locations of coronary arteries but, at this time, cannot depict hardened arteries reliably.

The authors predict that further development of MRI along with myocardial perfusion imaging and coronary angiography will lead to a low-cost all-in-one testing method. They also anticipate that improved hardware and software will enable automated acquisition of whole-heart images in as little as 10 to 20 s. (Canadian Medical Association Journal, Oct. 10, 2006, pp. 911-917).