9.4 T Promises Greater Function, New Purpose for MR

A new 9.4 T MR unit at the University of Illinois at Chicago (UIC) has the power to image a wide range of elements, shifting the function of MR from anatomical to metabolic and its purpose from repair to prevention, said Keith Thulborn, M.D., Ph.D. (left), director of the Center for MR Research at UIC. At right is Ian Atkinson, Ph.D., manager of the 9.4 T unit.

A new 9.4 T MR imaging unit at the University of Illinois at Chicago (UIC)—the most powerful in the world for human use—has the power to go beyond imaging of hydrogen to imaging a palette of elements such as carbon, sodium, phosphorous, oxygen and nitrogen.

The power to image those elements shifts the function of MR from anatomic to metabolic and its purpose from repair to prevention, said Keith Thulborn, M.D., Ph.D., director of the Center for MR Research at UIC.

UIC hired Dr. Thulborn—responsible for establishing the first 3.0 T clinical MR imager at the University of Pittsburgh in 1993—as it ushered in the 21st century with a goal to make UIC a center of excellence in human imaging. Eight years later, that decision has borne powerful imaging fruit, as safety trials were recently completed on the 9.4 T scanner.

Dr. Thulborn, a professor of radiology, physiology and biophysics, said his goal was not to simply increase the strength of the MR imager but to fundamentally change how it is used.

"The concept wasn't just to do what we can do at 3.0 T," said Dr. Thulborn. Rather than work with imaging of the hydrogen nucleus, as in most clinical uses, Dr. Thulborn envisioned the utility possible with the wider range of elements.

"We want to look at the development and expression of genes and the function of the cellular machinery they control," Dr. Thulborn said. "We want to look at the machinery of the cells and tissue, rather than just the anatomy, and to move in a completely new biochemistry dimension of medically relevant information."

"Metabolic Toolbox" Imagined

Metabolic imaging, now within reach using a powerful MR unit like the 9.4 T, is the key to predicting disease and preventing "catastrophic changes," thus potentially cutting healthcare costs, said Dr. Thulborn.

Dr. Thulborn said he believes MR imagers can image sodium as a measure of tissue viability, making it an invaluable tool when assessing, for example, the effectiveness of treatment to reduce the size or extent of brain tumors. Likewise, he said he sees the 9.4 T unit as effective for imaging oxygen-17 for measuring oxygen consumption in cells—his team's "next big target." The UIC researchers also hope to test the imaging of carbon-13 to monitor glucose metabolism in the brain and phosphorus metabolism in cells' central bioenergetic pathways.

"The goal is to create a metabolic toolbox that should allow us to look at the cellular machinery very early in a disease and be able to monitor interventions early in the disease process," said Dr. Thulborn.

3.0 T magnets are common in clinical use, with the number of 7.0 T magnets increasing across the country and the world. Currently, FDA safety limits for human MR are at 8.0 T. Dr. Thulborn's team is working through FDA safety trials in order to use the 9.4 T for its intended purpose.

The first of those safety trials has been led by Ian Atkinson, Ph.D., an assistant professor in the UIC Center for MR Research and manager of the 9.4 T unit. The safety trial conducted in the summer of 2007 involved 25 healthy volunteers, using sodium imaging and taking cognitive and vital sign readings before and after the subjects' exposure to the 9.4 T field. Subjects reported no significant side effects, other than mild discomforts such as a metallic taste in the mouth and spinning sensations, said Dr. Atkinson. He noted that these sensations are well-known and common at clinical field strengths.

The team is now proceeding with more trials for the imaging of oxygen in healthy volunteers as well as further testing of sodium imaging in hospitalized patients.

9.4 T Innovations Can Improve 3.0 T, 7.0 T

A summer 2007 safety trial on the 9.4 T MR unit at the University of Illinois at Chicago involved imaging sodium in 25 healthy volunteers and taking cognitive and vital sign readings before and after the subjects' exposure to the 9.4 T field. Subjects reported no significant side effects other than the mild discomforts, such as a metallic taste in the mouth and spinning sensations, commonly reported at clinical field strengths. More trials are under way to image oxygen in healthy volunteers as well as further testing of sodium imaging in hospitalized patients.

In addition to the obvious increase in power, the 9.4 T unit also increases acquisition speed, said Dr. Atkinson. "3.0 T takes roughly eight minutes to get an image," he said. "We can get a higher quality image in the 9.4 T unit in four minutes."

The UIC program is in year eight of its 10-year plan and Dr. Thulborn is pleased with the progress. "We are making sure these tools are appropriate for early investigation of disease," he said. "Then, after these 10 years, we'll be establishing the sensitivity of each tool in the toolbox for each of the diseases we're interested in." Those areas of interest, said Dr. Thulborn, include dementias and neurodegenerative and psychiatric diseases. "We want to basically cover the gamut of neurology and psychiatry," he said.

At this stage the 9.4 T MR unit is obviously a singular and unique research tool, but the data taken from the powerful MR unit will hopefully translate downward to 7.0 and 3.0 T units, said Dr. Thulborn.

"Many of the things that we've learned at 9.4 T imaging have improved the quality of imaging at 3.0 T," he said. "We're looking at how we can transfer technology down from 9.4 T to the 3.0 T platform."

Dr. Thulborn said he also believes that potential use of the team's "metabolic toolbox" with 7.0 T platforms could further enhance the use of those platforms in the near future. "We'll take our toolbox to the 3.0 T, but I think over the course of the next five years, the 3.0 T market will move to 7.0 T," he said.

With the shift from 3.0 T to 7.0 T, said Dr. Thulborn, "hopefully we'll start to see early interventions being made based on metabolic parameters, not just anatomic parameters."