A 7 Tesla Whole Body Scanner, manufactured by GE Healthcare and weighing 42 tons, or the equivalent of six adult male elephants, has found its home on the UI campus. The UI is one of only about 20 research institutes in the United States—and only about 40 worldwide—with this type of instrument.
How does it work? This MRI scanner uses a powerful 7 Tesla magnetic field and radio waves to create three-dimensional images of internal body structures and organs. Hydrogen atoms in water molecules present in human blood and tissue can act like tiny magnets. When they are placed in a strong magnetic field, they align with the field. Radio waves produced by the scanner excite the hydrogen atoms causing them to spin like mini gyroscopes. As the hydrogen atoms relax from this exited state, each emits a unique, characteristic energy signal that is detected by the scanner. A computer processes all the signals and uses the information to create a 3D image of the tissue being examined.
Unlike CT scanning or general X-ray studies, no ionizing radiation is involved with MRI scanners.
How strong is the magnet? When an electric current is passed through the superconducting magnet’s specialized coils (made of niobium-titanium), a strong, uniform magnetic field forms. The magnetic field strength is measured in Tesla (T). Most MRI scanners used for clinical purposes have field strengths of 1.5 or 3 Tesla. The new research scanner has a 7 Tesla field. (By comparison, the Earth’s magnetic field is approximately 3.1 × 10−5 Tesla.)
Once the scanner is energized, it will remain a magnet without any additional energy being used as long as it stays extremely cold. Liquid helium, which boils at 4.2°K (-452° F), is used to keep the scanner cold.
What will it be used for? The scanner will produce high-resolution images of microscopic structures within the human body and brain, allowing researchers to measure subtle changes in the size, function, and metabolism of specific brain structures associated with disease. For example, the scanner will let researchers measure tiny fluctuations in blood flow and metabolic processes that signal differences in brain activity. UI researchers will use the 7T scanner to investigate how the brain processes sound information; look at subtle abnormalities in white matter caused by brain disease and trauma; and detect age-related brain changes that affect decision-making.
How was it paid for? In 2010, the UI was awarded a $7.97 million grant from the National Center for Research Resources, part of the National Institutes of Health, to purchase a whole body 7T MRI research scanner.
Where is it housed? The scanner is now on the Carver College of Medicine campus in the basement of the new Pappajohn Biomedical Discovery Building and will be supported by the Iowa Institute for Biomedical Imaging. The scanner vault is lined with a special copper-impregnated fabric to block entry of external radio frequencies that would interfere with the MRI scanner’s own RF fields. The magnet is actively shielded to contain the powerful 7 Tesla magnetic field generated by the scanner.
University of Iowa researchers conducted the first magnetic resonance imaging study to identify the presence of brain abnormalities in patients with schizophrenia in the early 1980s. Since then, thousands of magnetic resonance studies have been conducted and scanners have become popular research tools used by investigators across a variety of fields at the University of Iowa, including business and engineering. Prior to MRI, researchers were limited to viewing the body’s structures and organs through invasive surgeries and often only after a person had died.
The University of Iowa’s rich tradition of conducting cutting-edge imaging research will be enhanced by the addition of a 7 Tesla (7T) Scanner. The 7T scanner will allow UI investigators to remain at the forefront of magnetic resonance imaging (MRI) research and to conduct studies that simply were not previously possible, according to Vince Magnotta, associate professor in radiology and director of the UI’s Magnetic Resonance Imaging facility.
Matthew Howard, III, MD, professor of Neurosurgery:
“We need the 7T scanner to help us with our research into how the human brain processes sound information (like speech). From work in experimental animals we know that the hearing part of the brain is parcellated into multiple discrete auditory fields. These fields have specialized functions and distinctly different anatomical patterns at the cellular level. These differences cannot be detected using standard MR (magnetic resonance) scanners. The enhanced capacity of the 7T scanner to image subtle differences in the cellular make up of different brain regions will allow us to distinguish different auditory fields in human subjects. That information will help us understand how to interpret our findings when we record brain responses to sounds that are presented to our neurosurgery patients with intracranial electrodes.”
Peg Nopoulos, MD, professor of Psychiatry/professor of Neurology, Pediatrics:
“The 7 Telsa Magnetic Resonance Imaging machine will provide a unique opportunity for the imaging research community here at Iowa. Only a few institutions around the world have access to this level of technology. The 7T’s high field magnet improves all levels of brain imaging, including 1) higher resolution of tissues and structures used for structural (obtaining volumes) imaging; 2) shorter acquisition protocols so that subjects won’t need to be in the scanner as long as they would previously; 3) more opportunities for improvement in methods that detect brain chemicals; 4) improved visualization of cerebral vasculature; and, 5) higher quality of data from Diffusion Weighted Imaging which allows quantification of white matter microstructure.
“These opportunities allow for more refined assessment of brain structure and function, advancing research and understanding of both the normal brain and the pathologic process of disease that may cause abnormalities in the cerebral white matter. We are beginning a new project on Myotonic Dystrophy – a genetic disease, and are considering using the 7T machine to further investigate this individuals living with this disease.”
William Hedgcock, BA, PhD, assistant professor of Marketing:
“I’m excited to see the 7T get installed. My lab does decision neuroscience, or Neuroeconomics, research. Specifically, we examine how neural or physiological changes affect decision-making. Most of our current research is focused on determining how age-related neural changes affect financial decision-making. Given the number of people who are 65 years+ and living on their own, this is an increasingly important issue.
“Compared to the 3 Tesla scanner, the 7T provides better spatial and temporal resolution, and a better signal-to-noise ratio. Better spatial resolution means we can detect age-related changes that we couldn’t detect before. It also means we will be able to locate these changes more precisely. Better temporal resolution means we will be able to determine how areas of the brain interact during decision-making. This means we can learn which areas are active during decision-making, and how these areas coordinate during the decision-making process. Better signal-to-noise ratio means we can detect differences we couldn’t detect before and/or have shorter experiments. This is especially important with seniors since physical impairments make it difficult to perform long fMRI studies.
“Furthermore, this scanner improves education. I have undergraduates, MBAs, and PhDs working in my lab. Many of these students help with our fMRI studies. Access to the 7T (and 3T) provides these students with a unique educational experience that cannot be offered at most other universities.”