MRI scans may accurately clock time of stroke

When a patient experiences a stroke, time is of the essence in order to qualify for the most effective treatment — but often stroke victims are unable to determine or communicate when their stroke started. MRI scans could be useful in those cases, according to a study published online Tuesday in the journal Radiology. The scans can accurately determine if a patient experienced a stroke within the 4.5 hours allowable for treatment with the highly effective clot-busting drug, tissue plasminogen activator (tPA), the study found. tPA alleviates blockages in the cerebral arteries if given within 4.5 hours of stroke onset.

Though a large preponderance of strokes are caused by occlusion (obstruction) of a major blood vessel to the brain, a significant minority of strokes are caused by a brain hemorrhage. The timing of tPA treatment is critical because if it is given too late, the drug will substantially increase the risk of brain hemorrhage. While the American Heart Association, the American Stroke Association and the European Stroke Association began recommending use of tPA within the 4.5 hour time frame in 2008, the U.S. FDA has not yet revised its three hour standard.

Researchers examined MRI images for 130 patients aged 65 on average who were treated for clot-induced stroke at Saint-Anne Hospital in Paris between May 2006 and October 2008. Sixty-three patients had MRIs within three hours of stroke onset while 67 had MRIs between three to 12 hours following their stroke. The radiologists could predict with greater than 90 percent accuracy if a patient had experienced stroke symptoms for more than three hours.

ACSH’s Dr. Gilbert Ross is encouraged by these results. “This is a very important step. It will allow patients whose time of stroke is unknown to get tPA if it can be determined with 90 percent accuracy. But the choke point here is getting into the MRI machine. It’s not always readily available — and patients can be unstable or have other complications,” he says.

According to the Internet Stroke Center, stroke kills more than 140,000 people in the United States each year, making it the third-leading cause of death.