Atrial fibrillation, the most common form of cardiac arrhythmia, affects 33.5 million people worldwide. The slow, sluggish blood flow caused by atrial fibrillation can lead to blood clots, which then travel to the brain and initiate stroke. The risk of blockage or hemorrhage of a blood vessel, however, is difficult to predict.

Michael Markl, a professor of biomedical engineering at Northwestern University, has developed a new imaging technique that can help predict who is most at risk for stroke. The breakthrough could lead to better treatment and outcomes for patients with atrial fibrillation.

Called “atrial 4D flow CMR,” Markl’s cardiac magnetic resonance (CMR) imaging test detects the blood’s velocity through the heart and body. Without the use of contrast agents, the non-invasive program images blood flow dynamically, and in three spatial dimensions. The software also integrates into current MRI equipment without the need of special hardware and scanners or equipment upgrades.

“It allows you to measure flow, diffusion of molecules, and tissue elasticity. You can interrogate the human body in a very detailed manner,” said Markl.

In a pilot study with 60 patients and a control group, Markl found that atrial fibrillation patients who would have been considered high risk for stroke by the traditional scoring system in fact had normal blood flow, while patients who were considered lower risk sometimes had the slow blood flow indicative of potential clotting.

The Northwestern University researcher plans to continue following atrial fibrillation patients as a part of a long-term study to better understand the predictive power and diagnostic value of his new imaging technique.