Superparamegnetic particles as MRI temperature contrast agent

ORAL

Abstract

A method of MRI temperature contrast developed by our group, which employs temperature dependent local field inhomogeneities due to a presence of micrometer sized magnetic particles and corresponding changes in image intensity (T2* contrast), faces limitations due to particle size. For human applications, large particles cannot be used as they face problems with delivery and secretion. Smaller particles are required. However, spin transverse relaxation process for such particles is no longer governed by a static dephasing regime and T2* temperature dependent inhomogeneity contributions vanish due to averaging by spin motion. We hypothesize that superparamagnetic particles may provide contrast mechanisms only if nuclear relaxation is temperature dependent. To test this hypothesis, we used Mn-Zn ferrite superparamagnetic particles with an average size of 7.8 ± 2.1 nm. Particles with a 2 mM concentration were embeded in agar gel for NMR and MRI measurements at temperature 5 - 50 oC. At 3.0 T, NMR results show that T1 is temperature independent, while observed NMR linewidth drops from 130 Hz to 70 Hz and T2 increases from 1.3 ms to 2.8 ms. Intensity of T2 weighted MR images depends linearly on temperature, providing the contrasting mechanism necessary for temperature determination.

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Presenters

  • Janusz Hankiewicz

    • BioFrontiers, University of Colorado, Colorado Springs
    • University of Colorado, Colorado Springs

Authors

  • Janusz Hankiewicz

    • BioFrontiers, University of Colorado, Colorado Springs
    • University of Colorado, Colorado Springs

  • John Stroud

    • BioFrontiers, University of Colorado, Colorado Springs
    • University of Colorado, Colorado Springs

  • Stephen Russek

    • National Institute of Standards and Technology Boulder

  • Karen Livesey

    • Physics, University Colorado Colorado Springs
    • University of Colorado, Colorado Springs
    • Physics, University of Colorado Colorado Springs

  • Casey Chalifour

    • Physics, University Colorado Colorado Springs

  • Giacomo Parigi

    • Magnetic Resonance Center, University of Florence, Italy

  • Zbigniew J Celinski

    • University of Colorado, Colorado Springs
    • BioFrontiers, University of Colorado, Colorado Springs

  • Robert Camley

    • University of Colorado, Colorado Springs
    • BioFrontiers, University of Colorado, Colorado Springs

  • Dorota Lachowicz

    • Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Krakow, Poland

  • Angelika Kmita

    • Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Krakow, Poland

  • Marta Gajewska

    • Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Krakow, Poland

  • Ela Trynkiewicz

    • Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Krakow, Poland

  • Roma Wirecka

    • Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Krakow, Poland

  • Marek Przybylski

    • Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Krakow, Poland