Physicians Unveil New Technique For Stroke Analysis; More Sensitive CT Scan Technique Will Bring Precise Diagnosis Into More Hospitals

"People are always looking for imaging tests to fine tune the selection of which patients get which treatments," says lead author Michael Lev, MD, of the MGH Department of Radiology. "Right now, there are very good magnetic resonance imaging, or MRI techniques, such as diffusion imaging. However, MRI is not universally available, and it's expensive."

The MGH-led group found that a special procedure using a CT scan could be performed instead of MRI. "The beauty of this technique is that it can be done on a helical CT scanner, which most emergency rooms already have," says senior author Lee Schwamm, MD, associate director of the MGH Acute Stroke Service.

The procedure involves a type of contrast-enhanced head examination called a perfusion-weighted CT scan that allows physicians to simultaneously look at blood vessels and blood flow to tissues in the brain. "The scan gives us information about the physiology of what's going on during a stroke," says Lev.

The current study consisted of twenty-two patients who each had a stroke and appeared in the emergency room within six hours of symptom onset. The researchers performed perfusion-weighted CT scans of the brain prior to therapeutic angiography and found that the technique allowed them to accurately predict the final size of the stroke and the clinical outcome of each patient. "In the past, people thought of CT scans as being insensitive to the early changes seen in stroke," says Schwamm. "We've demonstrated here that, with subtle changes to current methods, the sensitivity of CT can be increased and we can anticipate the minimum size of the final stroke."

Schwamm adds that the technique may help physicians decide on the proper course of treatment for different stroke victims. Either a ruptured blood vessel or a clot can produce symptoms of a stroke, and there are different subtypes of stroke that are seen when a vessel is blocked by a clot.

Accurate diagnosis is of utmost importance, because current medications can cause more harm than good to patients who suffer a stroke due to a ruptured blood vessel or to those with vessel blockage who already have extensive brain injury at the time of treatment.

In addition, administering treatment as soon as possible is extremely important, because earlier medical intervention is associated with better clinical recovery. The earlier the medical intervention, the better chance of recovery. The new CT scanning technique will now allow emergency room physicians to treat stroke victims quickly and appropriately.

The study was supported in part by research grants from the National Institutes of Health and by an educational grant from GE Medical Systems.

The Massachusetts General Hospital, established in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $300 million and major research centers in AIDS, the neurosciences, cardiovascular research, cancer, cutaneous biology, transplantation biology and photo-medicine. In 1994, the MGH joined with Brigham and Women's Hospital to form Partners HealthCare System, an integrated health care delivery system comprising the two academic medical centers, specialty and community hospitals, a network of physician groups and nonacute and home health services.