U-M scientists produce first MRI images of heart and lung tissue using laser-polarized xenon.
ATLANTA---University of Michigan scientists have put a new spin on an old technology by using xenon to generate the first high-resolution magnetic resonance images of the heart and lung tissue in a living laboratory rat. The key to their success is a customized laser system---designed and built by U-M physicists---that aligns or "polarizes" molecules of xenon gas and delivers it to the rat in controlled single-breath doses.
The U-M is one of several institutions developing next-generation magnetic resonance imaging (MRI) technology. Current MRI scanners use a powerful magnetic field to polarize protons in water molecules in the patient's body, much as a bar magnet aligns iron filings. These polarized protons are detected by radio waves and processed in a computer to produce detailed images of internal soft tissue.
Instead of water molecules, the U-M's prototype MRI system detects signals from molecules of xenon, which have been polarized by an laser optical pumping system before being inhaled by the animal.
"Xenon has many advantages for use in MRI technology," said Scott Swanson, co-director of the study and an assistant research scientist in radiology in the U-M Medical School. "The gas dissolves in the bloodstream where it is carried throughout the body to provide a direct, quantitative measurement of blood flow through an organ. It is non-reactive, safe in measured doses, and can be polarized in higher concentrations than water molecules. Plus we can differentiate relative concentrations of xenon in tissue, blood and gas, which is not possible with current technology."
Swanson presented the latest U-M research results and MRI images today during an invited presentation at the American Physical Society Centennial Meeting held here this week.
The U-M system's ability to detect polarized xenon in tissue, blood and gas
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Contact: Sally Pobojewski
pobo@umich.edu
734-647-1844
University of Michigan
22-Mar-1999