MRI clues identify stroke victims at risk of skull hemorrhaging

The appearance of parenchymal enhancement of stroke lesions and the hyperintense MCA sign on MRI may help identify stroke patients at risk of hemorrhaging in the skull, says a new study by researchers at Shantou University Medical College in China and the University of Toronto in Canada.

For the study, researchers analyzed the MRIs of 24 patients with ischemic stroke within five hours of symptom onset. Ten of the patients developed hemorrhaging within the skull. The parenchymal enhancement, in which certain cells appear brighter than usual on MRI, was found in six of those patients, and the hyperintense MCA sign, a special anomaly detected on MRI, was found in five of the 10. The 14 patients who did not develop hemorrhaging had no parenchymal enhancement or hyperintense MCA sign.

According to the researchers, intravenous tissue plasminogen activator (tPA) remains the only drug approved in North America and Europe for acute ischemic stroke treatment, but one of the most significant problems with this therapy is the risk of hemorrhaging within the skull. About half of all stroke patients experience some forms of this bleeding within the first week.

"The risk of life-threatening hemorrhaging increases tenfold after intravenous tPA, so the ability to identify patients at increased risk for secondary bleeding after acute stroke could potentially be helpful in increasing the effectiveness and safety of the therapy," said Dr. Gang Guo, MD, lead author of the study.

"This study suggests that patients with the presence of these signs on their MRIs may be at a higher risk for developing hemorrhagic complications following tPA treatment. This could lead to an extension of the treatment window beyond current time constraints (three hours after symptoms onset) in those patients who have a stable brain blood barrier," said Dr. Guo.

"We recommend that acute stroke imaging protocols that usually include gadolinium administration be followed with T1-weighted spin-echo MRI to screen for parenchymal enhancement and the hyperintense MCA sign," said Dr. Guo.

The full results of the study were presented on Monday, May 1, 2006 during the American Roentgen Ray Society Annual Meeting in Vancouver, BC.