Two of the main advantages of coronary CT angiography (CCTA) compared with coronary MR angiography (MRA) are speed and higher spatial resolution. Those gaps are quickly closing, however, as researchers have ramped-up coronary MRA with dedicated 32-channel cardiac coils and parallel imaging, according to a study presented at the recent Society of Cardiovascular Magnetic Resonance in Orlando, Fla.
Previous studies have shown that 3T is a promising platform for the detection of significant coronary artery stenoses with contrast-enhanced data acquisition. However, the imaging time—approximately 10 minutes—and spatial resolution—1.3 x 1.3 x 1.3 mm 3) remain major limitations, according to researchers.
Qi Yang, MD, from Xuanwu Hospital, Beijing, and colleagues from Siemens Healthcare and Northwestern University in Chicago, sought to evaluate the feasibility and diagnostic accuracy of 3T contrast-enhanced whole-heart coronary MRA using newly developed 32-channel cardiac coils, which greater acceleration factors and thus reduced imaging time and higher spatial resolution.
Researchers performed MRA on 20 patients with suspected coronary artery disease who were scheduled for catheter angiography using a 3T Magnetom Tim Trio scanner from Siemens. They also imaged five patients who were scheduled for CCTA. To reduce imaging time, they used parallel imaging, with an acceleration factor of three. Researchers used Multihance (Bracco) contrast agent. They defined significant stenosis as greater than 50 percent.
Only one patient did not successfully complete whole-heart coronary MRA. The average imaging time was six minutes.
On a per segment basis, coronary MRA delivered these results:
- sensitivity—81 percent
- specificity—96 percent
- positive predictive value—71 percent
- negative predictive value—98 percent
Yang and colleagues concluded that the new 32-channel cardiac coils, along with parallel imaging, allows improvements in imaging speed, study success rate and reduced dose of contrast agent when compared with conventional 12-channel coils.
In addition, “the higher study success rate achieved by 32-channel coils substantially improved overall accuracy of coronary MRA in detecting coronary artery disease when using the intention to diagnose method,” Yang said.