Study Calls For New Method Of Stroke Diagnosis
A study conducted by a team of stroke experts from the West Virginia University Health Sciences Center demonstrates that CT (computed tomography) perfusion imaging may dramatically improve stroke diagnosis. The study showed CT perfusion had 100 percent accuracy for detecting the large, devastating type of stroke. If adopted, this advancement in stroke detection will mean dramatically faster diagnosis time -- less than half the time of magnetic resonance imaging (MRI) screening -- and will enable physicians to provide more accurate and targeted care, thereby avoiding potentially life-threatening complications that can occur when "clot buster" (thrombolytic) drug therapy is used inappropriately.
According to the American Stroke Association, stroke is the third leading cause of death in the U.S. Each year, 780,000 Americans will fall victim to stroke and, sadly, more than 150,000 lives will be lost. The cost associated with stroke care is estimated to be $65 million and growing.
The most common form of stroke, ischemic stroke (obstruction within a blood vessel supplying blood to the brain), is treated with the clot-busting drug tissue plasminogen activator (tPA). However, for tPA to be most effective, the patient must receive an accurate diagnosis within three hours of the first sign of a stroke. Only three to five percent of stroke victims make it to the hospital within the critical three-hour window of treatment. While recent research demonstrates that there may be a larger window for tPA administration than previously thought, the issue remains that tPA can be dangerous when given to patients for whom it is not indicated, causing bleeding in the brain. Other recent research found that 40 percent of ER physicians would not use tPA because they were concerned about its potential risks, but most would use it if they had access to accurate brain scans and experts who could interpret the scans' results.
The WVU study, published in the October 2008 issue of The Journal of Emergency Medicine, is the largest to date examining CT perfusion, a technology that measures blood flow and is available to most hospitals. The study looked at the brain scan technology's effectiveness at early diagnosis of stroke and quickly determining accurate treatment. WVU researchers believe their results could change national stroke triage protocols.
"Our study reveals that the widespread use of CT perfusion is a practical way to help busy emergency departments save precious time in stroke diagnosis, to target treatment and reduce the risks of inappropriate thrombolytic use," said Ansaar T. Rai, MD, Assistant Professor of Neuro Radiology & Neurointerventional Radiology. "CT perfusion was able to pinpoint strokes with high levels of accuracy, particularly the major intracranial vessel strokes that result in more devastating outcomes."
The researchers demonstrated that CT perfusion is highly accurate, while decreasing diagnosis time. CT perfusion had a 92 percent rate for detecting infarcts, the most debilitating kind of strokes and a 100 percent rate for the most common type, acute ischemic stroke.
CT perfusion offers distinct advantages over MRI because most hospital emergency rooms use CT scanners for other purposes, they take one to two minutes to scan, and provide clear images even if a patient cannot lie perfectly still. Most hospitals need only to buy relatively inexpensive software to upgrade their systems and institute training programs -- making the use of CT perfusion highly accessible for most community hospitals.
This is particularly promising news for the cluster of states known as the "Stroke Belt," for inner city and rural hospitals that may rely on telemedicine, and for African Americans and Hispanics, who suffer strokes at much higher rates than other ethnic groups.
According to the Centers for Disease Control & Prevention (CDC), the Stroke Belt is a region of 10 states (Ala., Ga., Miss., N.C., S.C., Ky., Tenn., Fla., Ark. and La.) where, for the past 50 years, the mortality rate from stroke has been two times that of the rest of the nation. It has been suggested that high stroke mortality in these states is due in part to limited access to health care and specialized medicine.
The WVU study indicated that with CT perfusion's quick scan time and clear imaging, it can be an effective teleradiology tool for urban and rural hospitals, which are often understaffed and lack immediate access to specialists who can diagnose stroke quickly. The ability to transmit scans from one location to another through teleradiology shows encouraging preliminary results and may allow community hospitals in rural areas to treat stroke faster and more completely.
For African Americans and Hispanics, this advancement in stroke diagnosis and care could mean improvement in morbidity and mortality. African Americans, who have high population numbers within the Stroke Belt and medically underserved urban areas throughout the U.S., are the hardest hit by stroke. It is estimated that African Americans ages 45-64 have a 38 percent greater risk for stroke than whites, with African American males having the highest incidence. According to the Office of Minority Health, African American males are 60 percent more likely to die from a stroke than white males.
Hispanics are twice as likely as whites to suffer a stroke. Even though stroke is the fourth leading cause of death for Hispanics, they are stricken at a much earlier age than other groups. Hispanics are far less likely to receive diagnosis during the critical three-hour window of treatment.
CT perfusion can also combat what is known as the "weekend effect" for stroke mortality. Patients admitted to hospitals for stroke on weekends have a 14 percent greater risk of dying because of a lack of access to specialized medical care.
With the publication of this study, WVU is leading a high-tech effort to integrate care across multiple practice locations and make use of its collection of stroke brain scans, which is one of the largest in medicine. WVU researchers are also consulting with the government of the UK to help improve their country's national stroke program.