For the first time, researchers at the University of Virginia Health System have imaged the wall of carotid arteries that send blood to the brain while patients are being examined for symptoms consistent with an acute stroke or a mini-stroke (transient ischemic attack or TIA.) What the researchers found contributes much to the current theory about how strokes, and heart attacks as well, occur. Namely, that bleeding into the plaque in the arterial wall leads to strokes, not tight blockages as was once thought in the 1970’s and 80’s. Prior studies of this type were usually performed weeks or months after a stroke.
“The best predictor of which patient had a stroke was the presence of complex carotid plaque with evidence of hemorrhage or bleeding into it,” said Dr. Christopher M. Kramer, a UVA cardiologist who was the senior author on a study involving stroke patients at UVA. “We found that this imaging finding performed better than any other clinical marker as to whether the patient had a stroke on a certain side of their brain. So, this study corroborated with in vivo evidence the ongoing theories of what leads to a stroke or heart attack.”
Kramer and his colleagues at UVA performed a prospective observational study of 78 patients who came to the emergency room at UVA with acute stroke or TIA symptoms. With informed consent, Dr. Jaywant Parmar at UVA added on a ten-minute imaging exam when the patients were sent for a brain MRI. Of those 78, nearly half (37) were found to have experienced an ischemic stroke or TIA. Analysis of the results found a highly significant association between type VI plaque (demonstrating cap rupture, hemorrhage, and/or thrombosis) and an ischemic stroke or TIA. Ischemic strokes result from the blockage of an artery to the brain. TIAs are blockages to the brain’s blood flow that result in less severe symptoms lasting less than 24 hours.
The study used an imaging technique developed at UVA by John Mugler, PhD. This “black blood” technique employs 3-D MRI imaging of the carotid wall, turns off the signal from flowing blood and uses two different imaging approaches, called T1- and T2-weighted imaging. An MR angiogram was also performed.
“This represented a major collaboration at UVA between radiology, cardiology, neurology and public health sciences to apply this approach in a very sick patient population and make some important observations,” Kramer said. “More research is definitely needed down the road. If you could identify complex plaque, with hemorrhage, in patients at risk and treat them before a stroke that would be ideal.”
The study is published in the November 16, 2010 issue of the journal Circulation.
It can also be found online .