Safety trials with the world's most powerful medical magnetic resonance imaging machine, the 9.4 Tesla at the University of Illinois at Chicago, have been completed successfully.
A report on the trials, published in the Journal of Magnetic Resonance Imaging, suggests that this machine may soon offer doctors a real-time view of biological processes in the human brain.
Doctors believe that the 9.4T will give rise to a new era of brain imaging, wherein they will be able to observe metabolic processes and customize health care.
They hope that oncologists may one day be able to tailor radiation therapy based on a brain tumour's real-time response to treatment.
Currently, doctors have to wait weeks to see whether a tumour is shrinking in response to therapy. However, the 9.4T will make it possible to see if individual cells within the tumour are dying long before the tumour has begun to shrink, say the researchers.
The field strength of the 9.4T magnet is more than three times that of state-of-the-art clinical units. It is the first device that is large enough to scan the head and visualize the human brain.
"Because the more powerful magnet allows us to visualize different types of molecules, we are seeing activity in the brain along a completely different dimension," said Dr. Keith Thulborn, director of UIC's Center for Magnetic Resonance Research.
Current MRI visualizes water molecules to track biochemical processes. By visualizing the sodium ions involved in such processes instead, the 9.4T permits researchers to directly follow one of the most important energy-consuming processes in the cellular machinery in the brain.
During the trials, 12 healthy men and 13 healthy women were randomly exposed to the 9.4T scanner, in which they were exposed to a static magnetic field and to sodium imaging, and to a mock scanner with no magnetic field. An audio recording simulated the sound of a real scanner.
Vital signs and cognitive ability were measured in all volunteers before and after the sodium imaging at 9.4T and the mock scanning.
When volunteers were exposed to either the magnetic field or the imaging, there were no significant changes in heart rate, blood pressure, respiratory rate or other vital signs. There were no significant differences in the cognitive testing of volunteers following mock and real scanning.
The discomfort that the subjects reported the most while being moved into the magnetic field was light-headedness or vertigo. Some subjects reported a metallic taste, nausea, or a visual effect of seeing sparks. The sensations went away once they were stationary in the magnetic field.
Based on their observations, the researchers came to the conclusion that exposure to a 9.4T static magnetic field did not present a safety concern.
Now that the FDA-required safety trials have completed, the researchers are planning to begin putting the 9.4T to use.
"This initial evaluation of safety is only the first step towards realizing metabolic imaging of the human brain. We are now moving towards patient studies of sodium imaging and towards safety testing for oxygen and phosphorus imaging in humans," Thulborn said.
"These early metabolic signatures of cellular health have great potential to advance detection and monitoring of diseases in the earliest stages, when treatment can produce the greatest benefit," the researcher added.