MRI Is Valuable in Predicting Stroke

May 02, 2002

NEW YORK (MedscapeWire) May 03 — Magnetic resonance imaging (MRI) studies of the brain can help physicians predict which patients are at greater risk of stroke, a study of more than 3600 patients shows. The study was presented April 29 at the American Roentgen Ray Society annual meeting in Atlanta, Georgia.

Each of the patients underwent an MRI scan and the white matter of their brain was assessed and graded, Norman Beauchamp, Jr, MD, MHS, vice chair, department of radiology and radiological sciences at Johns Hopkins University in Baltimore, Maryland, and lead author of the study, says in a news release. The white matter grade ranged from 0 (no white matter abnormality) to 9 (almost all white matter involved), says Dr. Beauchamp.

Patients were followed closely for an average of 5 years for the occurrence of a stroke. "The risk of stroke was nearly 3% percent a year for participants with white matter grade 5 or higher compared to less than one percent for participants with grades zero or one," says Dr. Beauchamp.

"In addition, we demonstrated that a subset of individuals could be identified that had a very high risk for stroke," Dr. Beauchamp says. "We identified this group by evaluating the risk for stroke in participants with a single known risk factor in combination with those having a mildly elevated white matter grade."

The researchers were surprised to see how great the 5-year risk for stroke was in such subsets of people. For example, the risk for stroke in a patient with atrial fibrillation and a mild increase in white matter grade is increased 8 times.

"The potential significance of this finding is that older individuals in these high risk subgroups may benefit from more aggressive therapies to prevent stroke," says Dr. Beauchamp. Previous studies have shown that white matter grade is highly correlated with other known predictors of stroke, including age and sex, notes Dr. Beauchamp. "We figured in these factors and still concluded that white matter grade, in and of itself, was a stroke predictor, he says.

The study included patients, average age of 75 years, from 4 communities across the United States (Forsyth County, North Carolina; Pittsburgh, Pennsylvania; Sacramento County, California; and Washington County, Maryland). The study was funded by the National Heart, Lung, and Blood Institute at the National Institutes of Health and is the largest evaluated cohort of participants undergoing cerebral MRI for the evaluation of cerebrovascular disease.