Colorful Magnetic Resonance Imaging

Microengineered magnetic particles could bring color to traditionally gray-scale magnetic resonance imaging (MRI), U.S. government scientists report (Nature 2008, 453, 1058). Gary Zabow of NIST and NIH and coworkers created various magnetic microstructures with geometries that produce distinct radio-frequency signatures. Those signatures can be converted into a rainbow of optical colors on a computer screen. Traditional MRI contrast agents are chemically synthesized metal complexes with paramagnetic properties. These agents alter the magnetic field surrounding hydrogen nuclei in water, but not in a way that easily enables distinguishing between different types of tissues. The researchers designed nickel particles to have an open, double-disk sandwich structure, which they created with conventional microfabrication techniques. Each particle type is slightly different—for example, having a thicker disk or a wider gap—to create a customized magnetic field that effectively yields a specific color that can be associated with particular tissues. The researchers say much work must be done before these sensitive and tunable particles can be routinely used in people.