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Print 20 comment(s) - last by docawolff.. on Oct 14 at 8:40 AM

Xenon gas is hyperpolarized with laser light

Among the most effective tools in the arsenal of medicine for detecting and diagnostic disease and injury inside the body without cutting the patient open is Magnetic Resonance Imaging (MRI). The technology allows medical personnel to get a look inside the body of a patient to form better treatment plans and to diagnose serious diseases like cancer.

The 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.

Researcher 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."



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One little detail...
By docawolff on 10/13/2009 12:03:37 PM , Rating: 3
Interesting technique. One hopes the researchers remembered that Xenon is an anesthetic?

see: http://www.anaesthetist.com/anaes/drugs/xenon.htm

Of course, it takes a pretty high concentration of Xenon to reach even a hypnotic dose, but for those really high resolution MRI's, well, using Xenon would be... a gas!




RE: One little detail...
By Nexos on 10/13/2009 12:42:10 PM , Rating: 3
Xenon is actually completely inert (except in extreme conditions) and therefore not an anaesthetic or hypnotic by itself. On the other hand breathing pure xenon would lead to asphyxiation due to a lack of oxygen.


RE: One little detail...
By MrBlastman on 10/13/2009 1:11:49 PM , Rating: 2
Actually, according to that URL he posted:

4 stages of anaesthesia noted with 70% Xenon/ 30% oxygen.
Whole body paraesthesia & hypo-algesia.
Euphoria & increased psychomotor activity.
Analgesia with partial amnesia (after 3-4min).
Surgical anaesthesia with a degree of muscle relaxation.

Interesting. I've always thought of Xenon as something you put in flashlights. Go figure.


RE: One little detail...
By Drag0nFire on 10/13/2009 3:14:01 PM , Rating: 2
Anesthetics are an active area of research. Although we know what molecules work and what molecules don't, no patterns have been established. In other words, we don't actually know why anesthetics work. Several theories have been presented and discredited by counter examples. The many researchers currently trying to find the next best anesthetic are essentially shooting in the dark.

But suffice it to say, any small molecule that can permeate a cell membrane can be an anesthetic. The necessary dose depends on the affinity of the molecule for cell membranes. To develop a "good" anesthetic, we need one that has a strong affinity for cell membranes (so only a low dose is necessary), is disposed of quickly (so we can bring the person out of anesthesia), and is non-toxic (this is a big limitation).


RE: One little detail...
By docawolff on 10/13/2009 4:16:26 PM , Rating: 2
Interesting. Do you think that Xenon's mechanism at one atmosphere is similar to the mechanism that causes nitrogen narcosis (Martini's Law, if you are a diver) under high pressure?


RE: One little detail...
By S3anister on 10/14/2009 1:40:03 AM , Rating: 1
First and foremost, Xenon is an inert gas, INERT.

Of course it could be used or manipulated to create another chemical, as far as using it as an anesthetic? It wouldn't surprise me, however, i've never heard of it being used for one, and neither do I find the website posted by docawolff credible.

As for the Xenon gas being used for enhanced MR imaging, that's just freaking awesome.


RE: One little detail...
By MrPoletski on 10/14/2009 4:21:13 AM , Rating: 2
Intert?

It reacts with Flourine.

It's a noble gas.


RE: One little detail...
By docawolff on 10/14/2009 8:40:56 AM , Rating: 2
Hmmmm.... O.K., you didn't like the last citation, try this web site:

http://en.wikipedia.org/wiki/Xenon#Anesthesia

Couldn't you at least google "xenon anesthetic" before you proclaim that the web site I cited was not terribly credible?


RE: One little detail...
By lco45 on 10/14/2009 1:15:59 AM , Rating: 2
Being inert means it can't bond with other elements to form molecules, however it can still physically interact.

An analogy would be being beaten to death with a lead pipe. It's not lead poisoning that kills you, rather it's the physical interaction with the lead.

Another example would be helium. You get dizzy from breathing helium because it physically fills your lungs and excludes oxygen, even though it is also inert.

Luke


RE: One little detail...
By MrPoletski on 10/14/2009 4:22:58 AM , Rating: 2
But Helium causes you vocal chords to tighten.

Nobody here seems to have heard of Xenon Tetrafluoride...


RE: One little detail...
By mmcdonalataocdotgov on 10/14/2009 7:40:18 AM , Rating: 2
Helium does not cause your vocal chords to tighten. The cartoon voice effect is from the higher speed of sound in helium and the resulting resonant effect on your vocal cavity.


RE: One little detail...
By randomly on 10/14/2009 7:49:08 AM , Rating: 2
It's not Inert. Although it's one of the Noble gases it does form compounds.
There are over 80 Xenon compounds.

It is an anesthetic and has been used before in surgeries but it is expensive. It is about 50% more potent than N2O and so has the advantage for the patient of allowing mixtures with higher Oxygen content.


"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson











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