WEDNESDAY, June 18 (HealthDay News) -- "Micromagnets" could some day be injected into the body to add color to MRIs and enhance sensitivity and the amount of information provided by the images, according to U.S. researchers.

They said these micromagnets also could act as "smart tags" that identify specific cells, tissues, or physiological conditions for medical research or diagnostic purposes.

Currently, chemical solutions are used as image-contrasting agents in MRIs, which are primarily black and white, the researchers said.

The researchers at the National Institute of Standards and Technology and the National Institutes of Health have demonstrated the proof of principle for this new approach to MRIs. The findings are published in the June 19 issue of the journal Nature.

Tweaking the micromagnets' physical shape adjusts the radio frequency (RF) signals used to create MRI images. The RF signals are then converted into different colors by computers.

Different sets of micromagnets can be created to produce different colors. For example, specific sets of magnets could target different types of cells, such as cancerous versus normal. The cancerous cells could then be identified by tag color, the researchers said.

Each micromagnet consists of two round, vertically stacked magnetic discs a few micrometers in diameter, separated by a small open gap. Very low concentrations of the magnets in a person's body would be enough to enhance MRI images, the researchers said.

Further engineering and testing, including clinical trials, must be done before these micromagnets could be used in patients undergoing MRI exams.

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