Brain imaging advances can determine a greater number of stroke victims who can receive therapy later than previously thought, according to a new study published in The New England Journal of Medicine.

Currently, endovascular thrombectomy, or the physical removal of a blockage, is recommended for use up to six hours following stroke symptoms.

However, the results of the Endovascular Therapy Following Imaging Evaluation for the Ischemic Stroke (DEFUSE 3) trial finds removing brain clots up to 16 hours after onset of symptoms resulted in improved outcomes compared to standard medical therapy alone.

“These striking results will have an immediate impact and save people from life-long disability or death,” said Walter Koroshetz, MD, and director of the National Institute of Neurological Disorders and Stroke in an NIH news release. “I really cannot overstate the size of this effect. The study shows that one out of three stroke patients who present with at-risk brain tissue on their scans improve and some may walk out of the hospital saved from what would otherwise have been a devastating brain injury.”

The study was performed at 38 centers in the U.S. and was led by Gregory W. Albers, MD, and professor of neurology and neurological sciences at Stanford University School of Medicine.

Participants were randomized to receive endovascular thrombectomy with standard medical therapy or medical therapy alone.

In addition to the lengthened period in treating stroke victims, results found 45 percent of patients who received thrombectomy achieved functional independence compared to 17 percent who did not. Similarly, 14 percent of those who received treatment died within 90 days, compared with 26 percent in the control group.

During an Ischemic stroke, blockages cut off the delivery of oxygen and nutrients to brain tissue. Areas in direct vicinity of the blockage cannot be saved, but it has been suspected areas outside of that core can survive. Perfusion imaging has been in development to identify the salvageable brain tissue.

An automated software (RAPID) was used to analyze perfusion MRI or CT scans, and DEFUSE 3 researchers identified recoverable tissue up to 16 hours after a stroke.

“Although stroke is a medical emergency that should be treated as soon as possible, DEFUSE 3 opens the door to treatment even for some patients who wake up with a stroke or arrive at the hospital many hours after their initial symptoms,” Albers said in the release.