Magnetic resonance imaging is one of the most valuable diagnostic tools available to today's physicians. MRI gives medical practitioners highly detailed views of the inside of the human body and aids in the diagnosis of a wide range of diseases and injuries.

A revised understanding of nuclear magnetic resonance that has developed over the past decade holds the potential to make MRI an even more sensitive tool, one that can provide unprecedented contrast and resolution and could potentially detect tumors at an earlier, smaller stage. A team of researchers led by Warren S. Warren, a researcher at Princeton and the University of Pennsylvania Medical School, is using computational modeling on NCSA's IBM p690 system to support unusual experimental results that have added an important new chapter to established NMR theory.

The technique of nuclear magnetic resonance was first developed in the 1940s and is based on the quantum mechanical property of spin. Spin makes particles--protons, electrons, and atomic nuclei--behave like miniature magnets.

In NMR, a strong magnetic field is applied to a sample (water, for example, or the tissues of the body in the case of MRI). In response to this magnetic field, the nuclei in the sample align either with the field or in opposition to it. A radio frequency pulse is then applied, which knocks some of the nuclei into a new position, their spins askew. The axis of each tipped nucleus rotates, or precesses; the speed of the rotation varies depending on the type of nuclei and the strength of the fields that are involved.

The minute magnetic fields of these nuclei oscillate because of this rotation, and this creates a radio frequency current. These NMR signals can be detected and harnessed to create detailed images of the interior of the human body.

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Access Online | Posted 5-11-2004

Functional MR images showing areas of the brain activated by different activities.
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