Hyper-SAGE Amplifies Remote MRI Signals

Magnetic Resonance Imaging (MRI) investigations are among the most widely used medical tests in the world at this point, as they can provide a clear, 3D view of what is going on inside a patient. Cancer tumors and other abnormalities inside tissues and organs can also be viewed in extensive detail, which helps inform healthcare experts' decisions in establishing a cure. Now, the method gets a new boost. With the addition of the Hyper-SAGE method, it's now able to detect much smaller targets than ever before.

“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. 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,” research group member Xin Zhou explains.

In charge of the new research has been internationally renowned MRI expert Alexander Pines. The chemist holds a joint appointment, in the US Department of Energy (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab), and at the University of California in Berkeley (UCB). “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,” he 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,” he adds. The name of the new Hyper-SAGE method comes from “hyperpolarized xenon signal amplification by gas extraction,” the team reports. Details of the technique are published in the latest issue of the respected journal Proceedings of the National Academy of Sciences (PNAS).

“Xenon gas has an intrinsically long relaxation time, greater than 45 minutes, which means the signal lasts long enough for us to collect all the encoded information, which in turn can enable us to detect specific targets, such as cancer-related proteins, at micromolar or parts per million concentrations. Also, Hyper-SAGE utilizes remote detection, meaning the signal encoding and detection processes are physically separated and carried out independently. This is a plus for imaging the lung, for example, where the signal of interest would occupy only a small portion of the traditional MRI signal receiver,” Zhou adds.