Several imaging techniques can detect the presence of blockages in the arteries of the neck, a common cause of stroke. Dean Johnston and Larry Goldstein, of Duke University's Center for Cerebrovascular Disease, conducted the study, published in the April 24 issue of Neurology . They studied the medical records of 569 patients who over three years had undergone all three methods of imaging in order to evaluate the need for arterial surgery.
Duplex ultrasound is much like the imaging technique used to view babies in the womb.
Magnetic resonance angiography uses magnets and radiowaves to view the arteries-the same technology used to get an MRI image of the brain. Often, contrast angiography is used only if the results of the other tests are ambiguous or confusing. The procedure involves injecting a dye into the blood vessels leading to the brain and taking X-rays, and carries a minor risk of serious complications, including ironically, stroke and death. The researchers compared the diagnosis after each imaging procedure and discovered that the safer, non-invasive tests had a larger margin of error, which could result in misdiagnosis of the extent of an arterial blockage, putting patients at greater risk of later stroke. They found that DU alone would have resulted in a 29 percent margin of error, while MRA alone would have resulted in an 18 percent margin of error.