The content you've requested is available without charge only to active Sigma Xi members and
If you are an active member or an individual subscriber, please log in now in order to access this article.
If you are not a member or individual subscriber, you can:
Magnetic resonance imaging (MRI) machines use superconducting magnets to polarize hydrogen nuclei within the body, which are then made to emit telltale radio signals. Strong as they are, the magnets used in MRI scanners are not particularly effective. Even the most capable polarize only a tiny fraction of the hydrogen nuclei present. Thus hydrogen-poor materials, such airy lung tissue, provide little signal and are virtually invisible in the resultant images. But over the past decade physicists and physicians have been experimenting with another approach: polarizing nuclei outside the body before administering them to the patient. One strategy uses light to polarize an alkali vapor, which can then pass its polarization on to the nuclei of an appropriate noble gas. Detailed scans of the lung can be obtained after the patient inhales the specially prepared gas. Variations of this technique also allow one to measure the rate at which such a gas moves into the blood and to determine, for example, how different tissues in the brain take up the dissolved gas.
Connect With Us:
An early peek at each new issue, with descriptions of feature articles, columns, and more. Issues contain links to everything in the latest issue's table of contents.News of book reviews published in American Scientist and around the web, as well as other noteworthy happenings in the world of science books.
To sign up for automatic emails of the American Scientist Update and Scientists' Nightstand issues, create an online profile, then sign up in the My AmSci area.
JSTOR, the online academic archive, contains complete back issues of American Scientist from 1913 (known then as the Sigma Xi Quarterly) through 2005.
The table of contents for each issue is freely available to all users; those with institutional access can read each complete issue.
View the full collection here.
Receive notification when new content is posted from the entire website, or choose from the customized feeds available.