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T1 estimation for aqueous iron oxide nanoparticle suspensions using a variable flip angle SWIFT sequence

Authors

  • Luning Wang,

    1. Bioimaging Research Center, University of Georgia, Athens, Georgia, USA.
    2. Department of Physics and Astronomy, University of Georgia, Athens, Georgia, USA
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  • Curtis A. Corum,

    1. Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, USA
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  • Djaudat Idiyatullin,

    1. Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, USA
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  • Michael Garwood,

    1. Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, USA
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  • Qun Zhao

    Corresponding author
    1. Department of Physics and Astronomy, University of Georgia, Athens, Georgia, USA
    • Bioimaging Research Center, University of Georgia, Athens, Georgia, USA.
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Correspondence to: Qun Zhao, Ph.D., Bioimaging Research Center and Department of Physics and Astronomy, University of Georgia, Athens, GA. E-mail: qzhao@physast.uga.edu

Abstract

Purpose

T1 quantification of contrast agents, such as super-paramagnetic iron oxide nanoparticles, is a challenging but important task inherent to many in vivo applications in magnetic resonance imaging. In this work, a sweep imaging with Fourier transformation using variable flip angles (VFAs-SWIFT) method was proposed to measure T1 of aqueous super-paramagnetic iron oxide nanoparticle suspensions.

Methods

T1 values of various iron concentrations (from 1 to 7 mM) were measured using VFA-SWIFT and three-dimensional spoiled gradient-recalled echo with VFAs (VFA-SPGR) sequences on a 7 T MR scanner. For validation, T1 values were also measured using a spectroscopic inversion-recovery sequence on a 7 T spectrometer.

Results

VFA-SWIFT demonstrated its advantage for quantifying T1 of highly concentrated aqueous super-paramagnetic iron oxide nanoparticle suspensions, but VFA-SPGR failed at the higher end of iron concentrations. Both VFA-SWIFT and VFA-SPGR yielded linear relationships between the relaxation rate and iron concentrations, with relaxivities of 1.006 and 1.051 s−1 mM−1 at 7 T, respectively, in excellent agreement with the spectroscopic measurement of 1.019 s−1 mM−1.

Conclusion

VFA-SWIFT is able to achieve accurate T1 quantification of aqueous super-paramagnetic iron oxide nanoparticle suspensions up to 7 mM. Magn Reson Med 70:341–347, 2013. © 2013 Wiley Periodicals, Inc.

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