Boston, MA - Stress first-pass perfusion magnetic resonance imaging (MRI) followed by delayed-enhancement MRI is an accurate method for detecting significant coronary stenosis in patients with coronary artery disease or those suspected of having coronary disease, according to the results of a new study [1]. Compared with coronary angiography, the combined MR imaging measures yielded a diagnostic accuracy of 88%, report investigators.

"There are several other prior studies that use stress perfusion MR imaging with rest perfusion MR imaging to detect both inducible ischemia and prior infarcts," lead investigator Dr Ricardo Cury (Massachusetts General Hospital, Boston) told heartwire. "Here, we also use the stress and rest perfusion MRI, but we incorporated delayed-enhancement imaging because this is a more robust pulse sequence to image viable and nonviable myocardium. With that, you are better able to differentiate areas of inducible ischemia from a true perfusion defect in the myocardium. Using this approach with delayed-enhancement MRI, we showed that there is an increase in the diagnostic accuracy to detect significant stenosis."

The results of the study are published in the July 2006 issue of Radiology.

Speaking with heartwire, Cury explained that first-pass perfusion MRI pulse sequences are low in spatial resolution compared with the delayed-enhancement MRI pulse sequence, which can identify myocardial scarring. There is concern that with the lower resolution, some patients might have had a previous MI that was either silent or clinically missed. First-pass perfusion MR imaging combined with delayed-enhancement MR can help clinicians determine whether areas of perfusion deficits originate in viable or infarcted myocardium, he said.

In this study, 47 patients scheduled for coronary angiography were prospectively enrolled during a 12-month period. Of these patients, 33 subjects were suspected of having coronary artery disease (Group A) and 14 subjects had a history of myocardial infarction with recurrent angina, including patients who previously underwent coronary artery bypass graft (CABG) surgery (Group B). Coronary angiography demonstrated significant disease, defined as >70% stenosis, in 30 of 46 patients (one patient was excluded due to poor-quality MR images).

To determine accuracy of delayed-enhancement MRI combined with stress first-pass perfusion MR, the investigators tested the diagnostic performance of a variety of cardiac MRI measures alone and combined. The investigators found that the incorporation of cine, stress perfusion, and delayed-enhancement MR imaging or stress perfusion and delayed-enhancement imaging alone yielded the highest accuracy. Thus, the investigators conclude that it is reasonable to use a multimodality approach, including stress perfusion and delayed-enhancement MR, to detect significant stenosis.

Of the 30 patients with confirmed CAD, the combined MRI measures demonstrated disease with an accuracy of 88%. In patients with only one-vessel disease, the accuracy of MRI increased to 96%.

"Using stress perfusion and delayed-enhancement MR imaging is a viable option to noninvasively detect significant coronary stenosis," said Cury. "One of the advantages with this technique, of course, is that there is no radiation involved."

Cury noted that of the 32 patients suspected of having coronary artery disease but without a previous myocardial infarction, seven patients had subendocardial hyperenhancement during delayed-enhancement MR imaging. The vessel segments had "wall-motion abnormalities and perfusion deficits during stress, which is consistent with previous myocardial infarction in this population," Cury and colleagues write in the paper.