A US government funded study finds that CT scans used in emergency rooms spotted only 25% of strokes and hence have to be replaced by MRI scans which are better in identifying any type of stroke.
'This mantle should now be passed to magnetic resonance imaging,' wrote Dr. Geoffrey A. Donnan and colleagues at the University of Melbourne in Australia in a note accompanying the study report.
Doctors argue that MRI scan is time consuming, and the delay can prove fatal to a stroke patient.
'The time delay between MRI and CT may be around 15 to 20 minutes,' said Dr. Joseph Broderick, chairman of neurology at the University of Cincinnati College of Medicine. 'And in an emergency, 15 to 20 minutes can make a big difference.'
Researchers examined 356 patients by both CT and MRI machines and 217 of them were eventually diagnosed with acute stroke.
CT scans employ a type of X-ray, whereas the MRI uses powerful magnets to produce images.
Four experts, who had no other patient information, independently interpreted the scans. Experts could accurately diagnose acute strokes 83 percent of the time by observing the MRI scans, however while using the CT scans, they were only 26 percent successful.
Strokes are the second common cause of death worldwide, with an annual death rate of approx. 5.5 million deaths.
Although MRI scans are more accurate, CT scores in issues such as time and money. CT machines can produce images in two minutes, whereas the huge MRI machines take up to 30 minutes. They cannot be used for patients with pacemakers, metal objects, or pregnant women.
The cost of MRI scans is also significantly more than CT scans and requires skilled technicians to operate them.
The superiority of MRI in detecting stroke in ideal conditions is unquestioned,' said Dr. Lee Schwamm, an associate professor of neurology at Harvard Medical School.