Medicine: Making the Body Transparent

The mysteries of illness are revealed as never before

The throbbing of the brain to the beat of the heart, the coursing of blood through a maze of vessels, the dance of molecules in a working muscle, the stealthy growth of a tumor. For generations doctors have hunted for ways to see through skin and bone and into the whirring processes of life. The discovery of the X ray in 1895 by Wilhelm Roentgen opened the first window into the living body and inaugurated a new age in medicine. But anyone who has ever glanced at an X-ray film can perceive its Limitations. The picture gives little sense of depth, and while bones show up crisply enough, many of the softer tissues of the body are fuzzy shadows in shades of gray.

Ten years ago, doctors began to see more detail with a new kind of X-ray machine that uses a computer to construct clear, cross-sectional views of the body. The CAT scanner (for Computerized Axial Tomography) revolutionized radiology. But now that virtually every large hospital in the country has invested in one, at about a million dollars apiece, another revolution is under way: Nuclear Magnetic Resonance, or NMR. Currently being studied for approval by the Food and Drug Administration, the new technology is in experimental use at about half a dozen top U.S. medical centers as well as several overseas.

NMR exposes the internal landscape as never before. "Its development," says British Radiologist Brian Worthington of the University of Nottingham, "is as significant as the development of the X-ray machine one hundred years ago." Unlike CAT and other forms of X ray, NMR can "see" with clarity through the thickest of bones. Thus, without painful injections of contrast material, it can reveal damage from a stroke buried deep beneath the skull, find tiny spinal cord injuries, and make it possible to differentiate the gray and white matter of the brain. "For the soft tissue of the body," says Worthington, "NMR comes close to being the perfect imaging technique."

The revelations offered by NMR go beyond anatomical topography. Not only can doctors see internal organs, they can actually monitor certain processes occurring within them: blood moving through an artery, an arthritis-inflamed knee shrinking in response to steroid treatment, the reaction of a malignant tumor to therapy. "NMR opens up the whole wonderful world of in vivo chemistry," exclaims Neuroradiologist Sadek Hilal, who is testing the new technique at New York City's Presbyterian Hospital.

What makes NMR'S revelations even more remarkable is that they are produced without the ionizing radiation of X rays. In significant doses, X radiation can damage cells and may be a factor in causing cancer; it may be particularly dangerous to the rapidly dividing cells of children and pregnant women. NMR, by contrast, appears to be harmless. "We can look at the developing brain of an infant easily and safely," says Dr. Robert Steiner of London's Hammersmith Hospital.