In Focus

In a remarkable cross-pollination of astrophysics and medicine, Harvard physicists studying the origin of the universe are applying recently developed techniques to a promising new method of medical diagnosis.

The Harvard-Smithsonian Center for Astrophysics (CfA) is teaming up with Harvard-affiliated Brigham and Women's Hospital to improve magnetic resonance imaging (MRI), a technique commonly used for diagnosis of disease.

In the course of his research at CfA, Ronald L. Walsworth and his team have developed a xenon gas laser polarization technique that may enhance the capabilities of MRI.


Building on a theory by Soviet physicist Andrei Sakharov, Walsworth, physicist Eduardo R. Oteiza and co-workers have been working on detecting an electric dipole of xenon to gain insight into the laws governing the formation of the universe.

In a recent Smithsonian Institution Research Reports, Walsworth explained how difficult it was to detect the dipole, saying that if one were to blow up an the size of the Earth, the xenon dipole wouldamount to less than the width of a human hair.


To further their research into the origin ofmatter, Walsworth, Oteiza and Timothy E. Chupp ofthe University of Michigan developed aninexpensive technique for producing the magnetizedxenon gas needed to measure the dipole. Only aftertalking to scientists doing similar research atPrinceton and SUNY Stonybrook did Walsworthrealize the advantages his magnetizer couldprovide for MRI.

MRI relies on magnetizing the hydrogen atoms inwater molecules in the patient's body, settingthem spinning in one direction so that they createa weak electrical signal which is then convertedto a computer image.

Xenon, an inert gas already used in hospitalsas an anesthetic, can be pre-magnetized with alaser using Walsworth's method and inhaled by thepatient. The xenon then diffuses throughout thebody almost instantly, allowing a properly tunedMRI to detect the image.

Because the gas is premagnetized, MRI machinesdetecting xenon only require a weak magnetic fieldand can probably be made much smaller thanconventional imagers. Walsworth says he hopes thenew MRI's compact size will allow it to be broughtaboard the space shuttle to provide data on howzero gravity affects the body.

The xenon gas may also allow doctors to use MRIfor relatively waterfree organs such as the lungs.

Although Walsworth is busy applying xenonmagnetization to MRI, he says he is not postponingany of his astrophysical research. "We're notgoing to slow down at all," he says. "We'reexpanding and not switching gears."

Interdisciplinary collaborations between widelydivergent fields could potentially occur much moreoften, says Walsworth. "There's an inertia thatexists that people have to get past to think aboutthings more broadly," he says.

Walsworth says the rapid transfer of histechniques from physics to medicine was due inlarge part to his Cambridge location. "Being atHarvard with all the many groups working allows[one] to really find out about a new technologybecause there are so many people with so manycapabilities," he says.

When the MRI tie-in was realized, Walsworthsaid local scientists rushed to study and takeadvantage of the new idea like "piranha."

Walsworth says he hopes his contribution to MRIwill contribute to Harvard's ongoing plans forincreased interdisciplinary collaboration