9.4 Tesla MRI
9.4 Tesla MRIThe world's most powerful medical magnetic resonance imaging machine, the 9.4 Tesla at the University of Illinois at Chicago, has successfully completed safety trials and may soon offer physicians a real-time view of biological processes in the human brain.
The safety study was published in the November Journal of Magnetic Resonance Imaging in an issue focused on MRI safety.
Researchers and physicians hope that the 9.4T will usher in a new era of brain imaging in which they will be able to observe metabolic processes and customize health care.
Oncologists, for example, may one day be able to tailor radiation therapy based on a brain tumor's real-time response to treatment. Currently, physicians often must wait weeks to see if a tumor is shrinking in response to therapy. With the 9.4T, it will be possible to see if individual cells within the tumor are dying long before the tumor has begun to shrink.
The 9.4T magnet has a field strength more than three times that of state-of-the-art clinical units. UIC's 9.4T is the first such device 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 those 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.
The strength of magnetic resonance scanners has increased from less than 0.5T up to the first 8T in 1998. As human safety data became available, the FDA limits were revised upwards accordingly -- to the current level of 8T in 2003.
In this safety trial, 25 healthy volunteers -- 12 men and 13 women -- were exposed, in random order, 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. There were no significant changes in heart rate, blood pressure, respiratory rate or other vital signs when volunteers were exposed to either the magnetic field or the imaging. There were no significant differences in the cognitive testing of volunteers following mock vs. real scanning.
The most frequently reported discomfort was lightheadedness or vertigo when being moved into the magnetic field. A few 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.
The researchers concluded that exposure to a 9.4T static magnetic field does not present a safety concern.
With the FDA-required safety trials completed, UIC researchers will begin to put the 9.4T to use.
"This initial evaluation of safety is only the first step towards realizing metabolic imaging of the human brain," Thulborn said. "We are now moving towards patient studies of sodium imaging and towards safety testing for oxygen and phosphorus imaging in humans.
"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."
Research specialist Ian Atkinson, data analyst Holly Burd, postdoctoral research associate Laura Renteria, and Neil Pliskin, director of the neurobehavior program and neuropsychology service at UIC, made major contributions to the study.
The current industry standard for MRI systems is 1.5 tesla, which limits researchers to imaging water molecules. As a result, only anatomical changes can be detected and monitored. By contrast, the 9.4-tesla magnet, which is three times more powerful than current state-of-the-art clinical MRI magnets and more than 100,000 times stronger than the earth’s magnetic field, will enable UIC researchers to detect signals from sodium, phosphorus, carbon, nitrogen, and oxygen -- the metabolic building blocks of brain function and human thought. "Brain scanning is pushed to the limit with the current technology -- we need the sensitivity of the 9.4-tesla magnet to go beyond anatomic imaging to metabolic imaging," Thulborn said. "Metabolism provides the energy that drives brain function and therefore offers the key to uncovering the mysteries of the mind."
Thulborn worked with GE researchers to develop the 9.4-tesla MRI system.
"We developed this 9.4-tesla magnet in conjunction with Dr. Thulborn to provide the research community an in-depth look into how metabolism drives brain function and to provide answers to some of the brain’s greatest mysteries," said Dennis Cooke, vice president of GE Healthcare’s Global MR Business. "This is a one-of-a-kind tool in the hands of UIC’s capable researchers, who aim to identify, develop and apply innovative applications for diagnosing and treating patients." "GE is committed to developing technologies that enable researchers to push the frontiers of medicine and pioneer new treatments."
Applying 9.4-Tesla Research to Human Health and Learning
Specifically, Thulborn will use the 9.4-tesla MRI scanner to help identify and monitor many common conditions and diseases of the brain -- including stroke, Alzheimer’s, autism and mental illness. "The work we’re doing mapping human thoughts brings so much promise to the future of medical research, specifically to our ability to really understand more about brain diseases," said Thulborn. "The medical and social implications of this technology include more personalized healthcare and earlier intervention to prevent disease."
In addition, Thulborn plans to apply the 9.4-tesla system to observing and potentially treating cognitive learning disorders, like attention deficit disorder. "If we can understand how children learn, we can tailor educational programs to better teach them, regardless of whether they have learning difficulties. By understanding the different ways that the brain learns, more efficient and effective learning programs can be produced for such skills as reading, music and mathematics," said Thulborn.
