MONDAY, Dec. 1, 2003 (HealthDayNews) -- A powerful, speedy way to get magnetic resonance imaging (MRI) brain scans is proving valuable in fast diagnosis and treatment of strokes, British radiologists report.
MRI produces images by beaming brief bursts of magnetic fields into the body. Older machines, using just two coils to create those magnetic fields, take 20 minutes to produce an image. Newer eight-coil machines give doctors a usable picture in just three minutes.
That difference is vital because "stroke patients don't like being in an MRI very long," says study author Dr. Jonathan H. Gillard, a lecturer neuroradiologist at the University of Cambridge. MRI is a claustrophobic experience for patients, who must be sealed in a narrow tube, he notes. Someone who has suffered symptoms of a stroke is especially likely to fidget, movements that blur the MRI. For that reason, radiologists have preferred computed tomography scans, whose images are less detailed but are quickly available.
An ongoing study at the Cambridge Addenbrooke's Hospital shows the three-minute MRI is bearable for patients and gives better images than computed tomography, says Gillard, who is to present the findings Dec. 1 at the Radiological Society of North America's annual meeting in Chicago.
Used with 18 stroke patients, the three-minute MRI technique distinguished between those whose strokes were caused by burst blood vessels and those whose arteries were blocked by blood clots, Gillard reports -- vital information in determining treatment.
If a clot causes a stroke, "giving clot-busting drugs means that the patient will most likely get fuller recovery and be less disabled," he says. However, if the cause is a burst blood vessel, those drugs can cause further bleeding and more brain damage.
"If you give a clot-buster in the first three hours, the patient will benefit most," Gillard says. "This can tell you whether a blood vessel is blocked, and where the blockage is."
Eight-coil MRIs have been available for several years, but their use in diagnosing stroke "has been more delayed than I would like," says Dr. A. Gregory Sorenson, an associate professor of radiology at Harvard Medical School and a spokesman for the Radiological Society of North America.
The finding is not a great leap forward but signals "incremental improvements of better image quality, and that the improvement in technology is actually beneficial," Sorenson says.
That news is important because "for a long time, radiologists have been using computed tomography rather than MRI because of habit," he says. "Trying to convince a medical community to give up what they are used to takes a lot of effort."
"The major criticism of MRI has been that it takes too long," Sorenson says. "This report shows what many of us have known for a long time; that you can spend just a few minutes and get the information you need."
And even more powerful MRI technology is on the way, he says. At least one major manufacturer is expected to announce availability of a 32-coil MRI device soon.
"You might be able to get an image in just one minute," he says. "As you push to more coils, you get a clear climb in clinical payoff."
More information
Everything you want to know about MRI is told by the National Library of Medicine, while the American Stroke Association has a section devoted to diagnosing and treating brain attacks.
