In separate work, NIST researchers are exploring several candidate materials that can significantly boost image quality in low-field MRI scans.

MRI contrast agents — magnetic materials that are injected into patients and enhance image contrast — make it easier for radiologists to identify anatomical features or evidence of disease and are routinely used in MRI at conventional magnetic field strengths. However, researchers are just starting to understand how contrast agents might be used with the new low-field MRI scanners. At the lower field strengths of these scanners, contrast agents may act differently than at higher field strengths, creating opportunities to use new types of magnetic materials for image enhancement.


NIST scientists and their colleagues compared the sensitivity of several magnetic contrast agents in low magnetic fields. The researchers found that iron oxide nanoparticles outperformed traditional contrast agents, which are made of the element gadolinium — a rare-earth metal. At low magnetic field strength, the nanoparticles provided good contrast using a concentration of only about one-ninth that of the gadolinium particles.

Iron oxide nanoparticles also offer the advantage that they are broken down by the human body instead of potentially accumulating in tissue, noted NIST researcher Samuel Oberdick. By comparison, a small amount of gadolinium may accumulate in tissue and could confound the interpretation of future MRI scans if it is not taken into account.

NIST researchers collaborated with the University of Florence in Italy and Hyperfine Inc. in Guilford, Connecticut, and reported their findings in the journal Scientific Reports.

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