Coronary artery disease, the leading cause of death in the US, occurs when the arteries that supply blood to the heart become hardened and narrowed from a buildup of plaque on their inner walls. Current diagnostic methods, such as coronary angiography, usually involve invasive procedures that expose patients to radiation. Researchers from Massachusetts General Hospital and Harvard Medical School in Boston and from Beneficencia Portuguesa Hospital in Sao Paulo, Brazil, evaluated the accuracy of a noninvasive combined MRI approach in patients suspected of having or known to have coronary artery disease against the standard angiography technique. They reported that 47 patients underwent combined stress first-pass perfusion MRI, followed by delayed-enhancement MRI, using a 1.5-T imager from GE Medical Systems of Waukesha, Wis. In the first technique, the patients briefly held their breath while being injected with a contrast material to test for myocardial perfusion. The investigators used MRI to view the amount of motion in the left ventricular walls, then injected the contrast material again to obtain rest perfusion images. Approximately 10 minutes after that, they performed the delayed-enhancement MRI, which involved injecting another contrast medium. After several minutes, heart muscle that had been damaged from insufficient coronary artery blood supply appeared bright with the accumulation of the contrast medium, while normal heart muscle appeared dark. Two physicians interpreted the images for coronary artery disease. The investigators then compared their MRI results with traditional coronary angiography, which the patients also received. One patient’s results were excluded because of poor magnetic resonance images. Coronary angiography showed that 30 of the 46 remaining patients had the disease. Of these, the combined MRI technique detected the disease with 88 percent accuracy. The researchers believe that the method may be helpful for future noninvasive disease detection. However, the study did not compare other heart imaging techniques such as SPECT and PET, nor did it receive a quantitative analysis. They think that further investigation is required to establish accuracy of the method in larger populations. Radiology, July 2006, pp. 39-45.
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