New 3-D MRIPH Technique Helps Detect High-Risk Diseased Arteries

Sunnybrook researchers are the first worldwide to show a new form of MRI technique may prove to be a useful screening tool to prevent stroke and heart attack by detecting a specific type of dangerous plaque in the arteries of high-risk patients.

This new non-invasive technique provides radiologists a closer, more in-depth look into diseased arteries, providing information never seen before, and has the potential of changing the standard of imaging everywhere.

"There's been a major sea change in our research: we now know that the composition of carotid artery plaque is likely to be more predictive of future stroke events than the amount of narrowing in the blood vessel," says Dr. Alan Moody, lead investigator of a new study and radiologist in chief in the Department of Medical Imaging at Sunnybrook Health Sciences Centre. "The detection of bleeding within the walls of diseased carotid arteries may provide an opportunity to intervene and stabilize the plaque before it causes a vascular event, such as stroke and heart attack, or sometimes death."

The investigators show that magnetic resonance imaging of plaque hemorrhage (MRIPH), a three-dimensional magnetic resonance imaging technique, is capable of detecting the bleeding that occurs within a plaque in an artery. This can lead to thrombosis or even blockage in the artery resulting in a heart attack or stroke.

Until now, standard techniques to detect plaques included traditional ultrasounds, CT scans and MRI's, which focused on the degree of narrowing of the blood vessel. This new MRI technique however looks at the disease within the vessel wall itself, often before it causes any significant narrowing.

A first in North America, Dr. Moody brought the 3-D MRIPH technique to Canada from England.

"This technology gives us information we've never had before," says Moody, also a professor at the University of Toronto. "It tells us how dangerous the plaque is and if it is likely to rupture. Until recently, we didn't know the specifics about the type of blockage, we only went by how much narrowing it caused to the blood flow."

There are many unanswered questions regarding the risk of stroke in patients with complicated plaques in the carotid arteries, including the necessity for surgery in certain patients. This new technique may assist in selecting appropriate patients for surgery to remove a troublesome plaque, or to avoid surgery in patients who may not require it.

Dr. Moody and his fellow researchers have successfully applied the technique in the neck vessels of trial patients in both England and in Canada at Sunnybrook since 2003. "Results of larger trials will allow us to assess exactly how MRI of the vessel wall should be used in clinical practice after which we are looking forward to providing this service on a clinical basis to improve stroke prevention," adds Dr. Moody.

The 3-D MRIPH technique is easy to perform and interpret and it adds only a few minutes to an MR angiography exam.

The results of the study are published in the October 2008 issue of Radiology.