3D CMR shines as diagnostic tool for detecting CAD

Whole-heart 3D myocardial perfusion cardiac MR (CMR) accurately detected coronary artery disease (CAD) in a study that used fractional flow reserve (FFR) as a reference, making CMR a possible contender to techniques that are invasive and expose patients to ionizing radiation.

Standard 2D CMR has won praise for its high diagnostic accuracy but its limited coverage doesn’t allow physicians to assess myocardial ischemic burden in patients with suspected cardiovascular disease. Instead, they must rely on geometric assumptions. With advances in 3D CMR scan methods, they now can obtain whole-heart coverage.

Robert Manka, MD, of University and ETH in Zurich, and colleagues in Europe designed a prospective study to assess the diagnostic performance of whole-heart 3D myocardial perfusion CMR using FFR as a reference. They recruited 150 patients between 2011 and 2013 who were scheduled for diagnostic coronary angiography with FFR to assess suspected CAD to undergo CMR using 3.0 T MR systems (Philips Healthcare).

They considered a coronary stenosis with an FFR value of less than 0.8 to be hemodynamically relevant. Based on that measure, 56.7 percent of the patients had CAD. The sensitivity, specificity and diagnostic accuracy of 3D CMR was 84.7 percent, 90.8 percent and 87.3 percent, respectively. Its positive and negative predictive values were 92.3 percent and 81.9 percent, respectively.

Using quantitative coronary angiography as a reference, Manka et al found 3D CMR had a sensitivity, specificity and diagnostic accuracy of 76.5 percent, 94.2 percent and 82.6 percent with a positive and negative predictive values of 96.2 percent and 68.1 percent. For myocardial ischemic burden, it had a sensitivity and specificity of 84.7 percent and 92.3 percent.

The results showed that 3D CMR was robust with high diagnostic accuracy for detecting significant coronary artery disease. The myocardial ischemic burden “derived for 3D whole-heart myocardial perfusion CMR provides as accurate diagnostic tool for the detection of flow-limiting CAD,” they wrote.

Although they used 3.0 T MR at the five centers that participated in the study, 1.5 T MR systems would suffice, they wrote. They added that all five centers specialized in CMR imaging and centers with less experience might have different results.

“Today, the invasive assessment of the functional significance of coronary lesions is the basis of therapeutic decision-making, even though FFR measurements are invasive, time-consuming, and associated with radiation exposure rendering the method less attractive for monitoring patients,” Manka et al wrote. “To this end and based on the evidence presented here and elsewhere, 3D myocardial perfusion CMR may be considered a noninvasive alternative to stratify patients according to guidelines.”

They published their study online April 21 in Circulation: Cardiovascular Imaging.