Calibration and validation of TRUST MRI for the estimation of cerebral blood oxygenation

Authors

  • Hanzhang Lu,

    Corresponding author
    1. Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
    • Advanced Imaging Research Center, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390
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  • Feng Xu,

    1. Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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  • Ksenija Grgac,

    1. F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
    2. Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland, USA
    3. Department of Radiology, The Johns Hopkins University, Baltimore, Maryland, USA
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  • Peiying Liu,

    1. Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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  • Qin Qin,

    1. F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
    2. Department of Radiology, The Johns Hopkins University, Baltimore, Maryland, USA
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  • Peter van Zijl

    1. F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
    2. Department of Radiology, The Johns Hopkins University, Baltimore, Maryland, USA
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Abstract

Recently, a T2-Relaxation-Under-Spin-Tagging (TRUST) MRI technique was developed to quantitatively estimate blood oxygen saturation fraction (Y) via the measurement of pure blood T2. This technique has shown promise for normalization of fMRI signals, for the assessment of oxygen metabolism, and in studies of cognitive aging and multiple sclerosis. However, a human validation study has not been conducted. In addition, the calibration curve used to convert blood T2 to Y has not accounted for the effects of hematocrit (Hct). In this study, we first conducted experiments on blood samples under physiologic conditions, and the Carr-Purcell-Meiboom-Gill T2 was determined for a range of Y and Hct values. The data were fitted to a two-compartment exchange model to allow the characterization of a three-dimensional plot that can serve to calibrate the in vivo data. Next, in a validation study in humans, we showed that arterial Y estimated using TRUST MRI was 0.837 ± 0.036 (N=7) during the inhalation of 14% O2, which was in excellent agreement with the gold-standard Y values of 0.840 ± 0.036 based on Pulse-Oximetry. These data suggest that the availability of this calibration plot should enhance the applicability of T2-Relaxation-Under-Spin-Tagging MRI for noninvasive assessment of cerebral blood oxygenation. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.

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