MRI May Be the Future of Heart Disease Diagnosis
Oct. 11, 1999 (Atlanta) -- A new magnetic resonance imaging (MRI) test may enable some heart patients to get the tests they need but formerly couldn't have.
New software developed at Wake Forest University School of Medicine in Winston-Salem, N.C., now allows an MRI scanner to work at its highest speed while capturing images of the heart very near to "real-time." Whereas doctors previously had to wait an average of five minutes to see images from an MRI, they now can view them within seconds, thus more accurately showing the heart's movement.
This is an important step toward using MRI tests as a safe, effective, and noninvasive alternative for heart patients who can't undergo a more conventional echocardiography (ultrasound) test to image their heart, according to the researchers. The results of the study on the new procedure are published in the Oct. 12 issue of Circulation: Journal of the American Heart Association.
Ultrasound, a technique that visualizes the organs by bouncing sound-waves off of them, is ineffective for patients who are obese, have lung disease, or have previously had heart surgery. These conditions interfere with a clear ultrasound image of the heart. "Where this test comes in and saves the day is with the 10-20% of the population [unable to have ultrasounds]," study researcher W. Gregory Hundley, MD, tells WebMD. Hundley is an assistant professor of medicine in cardiology and radiology at Wake Forest.
The researchers conducted a stress test on 153 patients who needed to be tested for heart disease. The "stress" was provided by a drug that increased their heart rates to 85% capacity to mimic exercise. The patients were then placed in an MRI scanner for an average of 53 minutes.
Normally, both sides of the heart contract with equal force. If imaging shows that one side of the heart doesn't contract normally, then doctors can presume it isn't getting enough oxygen due to blocked blood vessels.
The study showed that this test safely and accurately predicted such symptoms of coronary artery disease. And, researchers say, the fast MRI was just as accurate as ultrasound at detecting blocked arteries.
In an editorial that also appears in the current issue of Circulation, Gerald M. Pohost, MD, and Robert W. Biederman, MD, write, "The future of MRI is no longer just over the horizon. This insightful work by Hundley et al. adds to the accumulating body of literature demonstrating the present ability and certain potential of a technology that will be the cornerstone for cardiovascular imaging in the next millennium." Pohost is a professor and Biederman is a resident at the University of Alabama School of Medicine in Birmingham.
Hundley tells WebMD that he sees the new MRI process as "complementary" to conventional stress tests. "We have had a wealth of experience over 15 years with ECHO stress test. They are inexpensive, portable, and can be put in any doctor's office." MRI scans are more expensive.