Xenon-129

Xenon was discovered in 1898 by Ramsay and Travers in the residue left after evaporating liquid air components. Xenon is present in the air we breathe in concentrations of about one part in twenty million. Xenon is odorless and non-toxic, a member of the “noble” or inert gases. Xenon is presently used commercially in automobile headlamps, and is routinely used medically as a contrast agent in Computed Tomography (CT) scanning. If breathed in sufficiently high concentrations for several minutes, it can induce a degree of euphoria and even anesthesia, like nitrous-oxide. It could find widespread medical use as an anesthetic if costs came down.

Natural xenon is composed of a mixture of nine stable (non-radioactive) isotopes. The isotope with 54 protons and 75 neutrons, Xenon-129, comprises 26.4% of the natural mixture. Only this isotope contributes to our magnetic resonance signals. Large-scale capabilities for enhancing the concentration of one isotope from a mixture of isotopes are now commercially available, which can raise the concentration of Xenon-129 from 26.4% to over 86%. Beginning with this chemically and isotopically purified gas, we are able to achieve magnetic alignments exceeding 50%, producing signals for clear diagnostic MRI scans. Note that no ionizing radiation is used either in the xenon or in the MRI scanning procedure, so scans can be repeated without health risk.