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
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.
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