According to research featured in the July 2006 issue of Radiology, a new cardiac magnetic resonance imaging (MRI) technique can non-invasively demonstrate blockage of the coronary arteries with high diagnostic accuracy.
The new technique called 'stress first-pass perfusion MRI' is different than the typical MRI sequences used to investigate the coronary arteries. With this combined technique, the researchers injected patients with a contrast material and then performed MRI at timed intervals to see if there was heart muscle ischaemia attributable to coronary artery blockage and if there was tissue death that indicated a prior heart attack.
Researchers at Massachusetts General Hospital (MGH), Harvard Medical School in Boston and Beneficencia Portuguesa Hospital in Sao Paulo, Brazil, compared their new imaging technique against the current diagnostic standard, coronary angiography.
In total, 46 patients with chest pain were enrolled in the study all of who were scheduled to undergo coronary angiography. The patients were divided into two groups; the first group included 32 patients suspected of having coronary artery disease (CAD) and the second included 14 patients with prior history of heart attack and suspected new arterial lesions. The MRI protocol included assessment of the left ventricle of the heart and blood flow during medicinally induced cardiac stress and rest and myocardial damage (delayed-enhancement technique). After MRI was completed, coronary angiography was performed for comparison.
The results showed that the traditional angiography demonstrated significant CAD in 30 of 46 patients (65%). Of these 30 patients, MRI demonstrated CAD with an accuracy of 88% and in patients with only one diseased vessel, the accuracy of MRI increased to 96%. In patients who had previously undergone coronary artery bypass graft (CABG), the accuracy of MRI was 90%.
"We have shown that cardiac MRI can be used reliably as an alternative to other more invasive detection techniques, due to its high diagnostic accuracy, its comprehensive evaluation of cardiac function, perfusion and viability and the lack of radiation exposure," said Dr Ricardo C Cury, lead author and director of clinical cardiac MRI at MGH.
He added that the diagnostic accuracy of this new MRI technique could potentially be used to enhance clinical decision-making and guide appropriate disease management when deciding whether or not to proceed with a more invasive modality.
"In addition to diagnostic accuracy, cardiac MRI is safe," Cury added. "It can provide information about the anatomy, function, blood flow and damage that the heart has sustained. MRI can also be used to assess the blood vessels in the body."
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