problem with detecting very early cancers with MRI is that the signal
is not strong enough for early cancer stages where it is most
treatable. A group of researchers has developed a new way to boost
the signal strength of MRI machines to allow the detection of cancers
at a much smaller stage.
Alexander Pines from the University
of California, Berkeley said, "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. 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."
Hyper-SAGE stands for
"hyperpolarized xenon signal amplification by gas extraction."
The technique takes the inert xenon gas and hyperpolarizes the gas by
hitting it with a laser light to produce a group of xenon atoms where
five out of every ten nuclei produce an MRI signal. Typically, only
about one in every 100,000 nuclei produces a MRI signal.
Xin Zhou said, "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."
The new technique is
also painless and easy to administer. Zhou says, "In a clinical
setting, a patient would inhale the hyperpolarized xenon gas which
would be dissolved in the blood and allowed to flow into the body and
brain. The exhaled xenon gas would then be collected and its MRI
signal would be detected. Used in combination with a target-specific
xenon biomolecular sensor, we should be able to study the
gas-exchange in the lung and detect cancerous cells at their earliest
stage of development."