Top Stories - Posted by Eric Gershon-Yale on Wednesday, March 21, 2012 9:47 - 1 Comment
To see into bone, MRI targets phosphorus
YALE (US) — Researchers have developed a new way of seeing inside solid objects, including animal bones and tissues.
The technique, a novel kind of magnetic resonance imaging (MRI), creates three-dimensional images of hard and soft solids based on signals emitted by their phosphorus content. The findings potentially open a vast array of dense materials to a new type of detailed internal inspection.
“This study represents a critical advance because it describes a way to ‘see’ phosphorus in bone with sufficient resolution to compliment what we can determine about bone structure using x-rays,” says study author Karl L. Insogna, director of the Yale Bone Center. (Credit: Yale University)
Straight from the Source
“We are extending the reach of MRI technology,” says Sean Barrett, a professor of physics and applied physics at Yale University and the principal investigator of research published the week of March 19 in the journal Proceedings of the National Academy of Sciences. Merideth A. Frey, a doctoral student in physics at Yale, is the paper’s lead author.
Traditional MRI produces an image by manipulating an object’s hydrogen atoms with powerful magnets and bursts of radio waves. The atoms absorb, then emit the radio wave energy, revealing their precise location. A computer translates the radio wave signals into images.
Standard MRI is a powerful tool for examining water-rich materials, such as anatomical organs, because they contain a lot of hydrogen. But it is hard to use on comparatively water-poor solids, such as bone.
The Yale team’s method targets phosphorus atoms rather than hydrogen atoms, and applies a more complicated sequence of radio wave pulses. These extra pulses are the key innovation that allow for high-spatial-resolution imaging of elements like phosphorus, which is a relatively abundant element in many biological samples.
So far, the new MRI method, which the researchers call “quadratic echo MRI of solids,” can only be applied to non-living objects. It generates too much heat, among other things, Barrett says. The new Yale method could also be applied to archaeological artifacts and oil- or gas-bearing rocks, for example.
In the experiments reported in PNAS, the Yale team generated high-resolution 3-D MRIs of phosphorus in a variety of ex vivo animal bone and soft tissue samples, including cow bone and mouse liver, heart, and brains.
The researchers say this new type of MRI would complement traditional MRI, not supplant it. MRI of solids should also be possible with elements other than phosphorus, they say.
Barrett’s project began about 10 years ago with a different aim—the study of silicon powders, part of a broader effort to advance quantum computing. “This shows how basic research in one area can have an unexpected impact on very different areas of science,” he says.
“This study represents a critical advance because it describes a way to ‘‘see’ phosphorus in bone with sufficient resolution to compliment what we can determine about bone structure using x-rays,” says Karl L. Insogna, a professor at Yale School of Medicine and director of the Yale Bone Center who contributed to the study. “It opens up an entirely new approach to assessing bone quality.”
Additional authors Michael Michaud, Joshua N. VanHouten, and Joseph A. Madri, all of the Yale School of Medicine, contributed to the research, which was supported by the National Science Foundation, the National Institutes of Health, and Yale University.
More news from Yale University: http://news.yale.edu/