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Doppler Imaging Identifies Patients at Risk For Stroke From Atherosclerosis

NEW ORLEANS, LA -- June 12, 2000 -- A group of radiologists from around the nation, led by Ochsner Clinic, have developed the first accurate and inexpensive screening test to detect patients at risk for stroke.

Using Power Doppler Imaging, a component of color flow Doppler ultrasound, radiologists are now able to identify patients at risk for stroke due to atherosclerosis.

Stroke is the third leading cause of death in the United States. It is the result of clogged carotid arteries or carotid stenosis due to atherosclerosis.

Led by Dr. Edward I. Bluth, Chairman of the Department of Radiology at Ochsner Clinic, this team of researchers have developed a screening test for carotid stenosis that compares favorably with mammography in its accuracy (89 percent), cost-effectiveness ($50-$80), and speed (five to seven minutes). And is the first accurate step in the identification of those patients who are truly in need of treatment.

Initial Evaluation of Power Doppler Imaging as a Screening Test for Carotid Artery Stenosis, published in the June 2000 issue of Radiology, details the use of ultrasound technology called Power Doppler Imaging (PDI) to visualize and measure blood flow through the carotid arteries.

"PDI can save lives by identifying those in danger, and at the same time eliminate the use of more expensive tests and treatments for those who do not need them," says Dr. Bluth.

Dr. Bluth states, "We hope that this inexpensive screening test will allow physicians to identify large numbers of asymptomatic people at risk for stroke. And limit further testing to those truly at risk."

The screening test is devised to be interpreted as "normal" or "abnormal". Those with an abnormal test will be referred for further evaluation with either a complete duplex ultrasound exam, a CT, MR or angiogram depending on their doctor's recommendation.

This study suggests that in the beginning, the screening process should focus on individuals who have at least one risk factor in addition to age. Smoking triples the risk of serious stenosis; elevated blood pressure or cholesterol also increases risk.

The screening test utilizes color imaging (similar to what meteorologists use on radar) to detect blood flow in major vessels. These images enable the physician to see the amount of, or lack of, blood flow in each vessel. Reduced blood flow indicates a blockage

In 89 percent of the 100 people examined in the study, images produced by the screening test allowed physicians to determine whether or not the patients were "normal" or "required further diagnostic evaluation." If patients had a blockage of 40 percent or greater they required follow up care.

It is expected that once available, the screening test will be inexpensive, costing between $50 to $80 (US).

Although a much larger study is necessary to confirm these results, initial outcomes are positive. Ochsner hopes to proceed to a larger, multi-institutional study.

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