In the first study, Pines and collaborators were able to nearly double the strength of MRI signals from hydrogen nuclei in solution, and to increase the signals of the surface atoms of a solid by a factor of one hundred. In the second study, Pines and Thomas Budinger, head of Berkeley Lab's Center for Functional Imaging, used pre-treated xenon to record the first observations of an anesthetic entering human red blood cells. Exposing these spinning nuclei to a strong magnetic field and then bombarding them with radio waves causes them to resonate at specific frequencies by which they can be identified. For MRI, it is typically the resonating frequencies of hydrogen nuclei in water molecules that enable researchers to produce images of organs and soft tissue. In recent experiments, Pines, Budinger and colleagues have used injections of xenon to deliver high concentrations of the gas directly into tissue.
Xenon is particularly well-suited for medical studies.
As an inert gas, its molecules can make physical contact with other types of molecules without affecting them chemically. Xenon is also readily absorbed in solutions, especially blood, but is repelled by water. Their results point the way for using laser-polarized xenon gas as an alternative to radionuclides for imaging physiological phenomena in the blood system and in tissue specific to the heart, brain, and other organs. A major challenge was to find a means of efficiently delivering xenon to the blood and tissues while maintaining its enhanced polarization. The polarized xenon gas was frozen at liquid nitrogen temperatures, sublimated, put into a solution, then shaken until it dissolved.