Hyper-SAGE Boosts Remote MRI Sensitivity
A new technique in Magnetic Resonance Imaging dubbed "Hyper-SAGE" has the potential to detect ultra low concentrations of clincal targets, such as lung and other cancers.
Development of Hyper-SAGE was led by one of the world's foremost authorities on MRI technology, Alexander Pines, a chemist who holds joint appointments with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley.
The key to this technique is xenon gas that has been zapped with laser light to "hyperpolarize" the spins of its atomic nuclei so that most are pointing in the same direction.
"By detecting the MRI signal of dissolved hyperpolarized xenon after the xenon has been extracted back into the gas phase, we can boost the signal's strength up to 10,000 times," Pines says.
"It is absolutely amazing because we're looking at pure gas and can reconstruct the whole image of our target. With this degree of sensitivity, Hyper-SAGE becomes a highly promising tool for in vivo diagnostics and molecular imaging."
MRI is a painless and radiation-free means of obtaining high quality three-dimensional tomographical images of internal tissue and organs. It is especially valuable for optically opaque samples, such as blood.
However, the application of MRI to biomedical samples has been limited by sensitivity issues. For the past three decades, Pines has led an on-going effort to find ways of enhancing the sensitivity of MRI and its sister technology, nuclear magnetic resonance (NMR) spectroscopy. Hyper-SAGE, the latest development, represents a significant new advance for both technologies, according to Xin Zhou, a member of Pines' research group.
"Hyper-SAGE is a totally novel way to amplify a solvated xenon MRI/NMR signal in that instead of a chemical process, which is what previous signal enhancement techniques relied upon, it is a physical process," says Zhou.
"Because gas can be physically compressed, the density of information-carrying polarized gas in our detection chamber can be much greater than the density of an information-carrying solution. This means we can detect MRI signals from concentrations of molecules many thousands of times smaller than can be detected with conventional MRI."
"This Hyper-SAGE image of xenon dissolved in water flowing through a phantom lung shows the intensity of the MRI signal 23 seconds into the process. The warm colors (red, orange and yellow) represent a stronger signal than the cool colors. (Credit: Image courtesy of Xin Zhou)"
Source: Lawrence Berkeley National Laboratory
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