MRI Program Developed to Advance Research

A new U.S. magnetic resonance imaging (MRI) research program has been developed to further the study of disease processes.

When powerful magnets line up the body's protons before radiofrequency waves can snatch their attention away, the mechanism is called spin physics. When signals generated by the movement are mathematically transformed into dramatic images of hearts, lungs, and other organs, the technique is called MRI.

"Protons normally would be pointing in many different directions,” said Dr. Tom Hu, director of the Small Animal Imaging Program at the Medical College of Georgia (MCG; Augusta, USA). "But if you put an object in the MRI, the magnet will line up the protons and what that does is generate the original, steady state. Then, by applying different radiofrequencies, pretty much like what you do with a car antenna, you can pursue radiofrequencies to perturb the system and you pretty much listen to it.”

When Dr. Hu, a biochemist and biophysicist, utilizes MRI scanning to see how calcium travels in and out of heart cells as the heart contracts and relaxes, and how that movement does not work so well in heart failure, a disorder resulting in oversized hearts with difficulty beating. Dr. Hu is trying to determine whether the metallic manganese ion, which can travel in the same manner as calcium, can enhance the signal and subsequent images he gets of how calcium cannot get back into cells after a heart attack.

The MRI that is the program's centerpiece looks like the human version except the cylinder the patient lies in is much smaller. However, it has a stronger magnet than the usual clinical grade units mainly because the organs of interest are so much smaller, according to Dr. Nathan Yanasak, an MRI scientist.

Many conventional MRI units are 1.5 Tesla and high-end clinical units are 3 Tesla, a measure of the density and intensity of a magnetic field. MCG's small animal MRI unit is 7 Tesla, not the strongest magnet available for research but one that enables good quality images of small organs comparable to those obtained by clinical machines.

Similar to what physicians do with patients, research scientists now use technology to help track disease progression over time and even to see if treatments work. In his own work, for example, Dr. Hu assesses development of heart failure by monitoring changes in calcium dynamic and heart structure.

Newer technology, on loan to the facility from Xenogen Corp. (Cranbury, NJ, USA), part of Caliber Life Sciences Corp., has enabled the lab to add genetic expression into the technology. The optical scanning system uses luciferase, the same enzyme fireflies use to glow, to identify gene expression.

The number of MCG scientists using the facility is considerable and increasing, according to its director. One MCG scientist, for example, is looking at blood flow in the brain of her diabetes model, and another is looking at stroke event and recovery.


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Xenogen
Medical College of Georgia