JACC: Accelerated cardiac MR perfusion imaging feasible for detecting stenosis

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Accelerated cardiac MR (CMR) perfusion imaging using scan acceleration techniques such as parallel imaging is clinically feasible and offers excellent diagnostic performance in detecting coronary artery disease (CAD), according to the July issue of Journal of American College of Cardiology: Cardiovascular Imaging.

CMR myocardial perfusion imaging performs favorably compared to SPECT and offers higher spatial resolution, particularly when combined with scan acceleration techniques such as k-space and time (k-t) sensitivity encoding (SENSE), according to Robert Manka, MD, from the Institute for Biomedical Engineering, University and ETH Zurich in Zurich, and colleagues.

The study was conducted in collaboration with researchers from departments of internal medicine and cardiology at the German Heart Institute in Berlin, the department of cardiology at the University Hospital Zurich and the division of cardiovascular and neuronal remodeling at the University of Leeds in Leeds, England.

In the study, 20 patients underwent CMR myocardial perfusion imaging using a 3T whole-body CMR scanner before diagnostic x-ray coronary angiography.

Perfusion images were obtained by the researchers using an extension of the k-t SENSE method using parallel imaging to double the spatial resolution of the k-t SENSE training images.

This extension, termed k-t SENSE+, permitted eight-fold nominal scan acceleration and an in-plane spatial resolution of up to 1.1x1.1 mm2, according to Manka and colleagues.

Perfusion scores derived for 16 myocardial segments were compared to quantitative analysis of x-ray coronary angiography. High diagnostic accuracy was achieved using CMR, for detecting stenoses greater than 50 percent and greater than 75 percent, respectively, wrote Manka and colleagues.

"The areas under the receiver-operator characteristic curves for the left anterior descending, left circumflex, and right coronary artery territories with stenoses greater than 50 percent were 0.75, 0.92, and 0.79, respectively," noted the authors.

In an accompanying editorial, Michael Jerosch-Herold, PhD, associate professor of radiology, Brigham and Women’s Hospital, Boston, wrote: “The investigators tested their new method on an MRI scanner operating at 3T, a field strength that is still rarely used for routine cardiac imaging in the clinical setting, but the higher field strength certainly compensated in part for any decrease in signal-to-noise ratio due to acceleration of the image acquisition.

“Manka et al present some results from an analysis of their studies in which the spatial resolution was reduced by post-processing, but arguably, they do not provide a conclusive answer yet. Rather, a larger, preferably multicenter study is needed to test performance at different spatial resolution settings in the clinical setting,” added Jerosch-Herold.