Two-dimensional single-shot diffusion-weighted stimulated EPI with reduced FOV for ultrahigh-b radial diffusion-weighted imaging of spinal cord

Authors

  • Nabraj Sapkota,

    1. Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
    2. Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, USA
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  • Xianfeng Shi,

    1. Department of Psychiatry, University of Utah, Salt Lake City, Utah, USA
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  • Lubdha M. Shah,

    1. Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, USA
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  • Erica F. Bisson,

    1. Department of Neurosurgery, University of Utah, Salt Lake City, Utah, USA
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  • John W. Rose,

    1. Department of Neurology, University of Utah, Salt Lake City, Utah, USA
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  • Eun-Kee Jeong

    Corresponding author
    1. Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA
    2. Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, USA
    • Correspondence to: Eun-Kee (E.K.) Jeong, Ph.D., University of Utah, Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, 729 Arapeen Drive, Salt Lake City, Utah 84108. E-mail: ek.jeong@utah.edu

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Abstract

Purpose

High-resolution diffusion-weighted imaging (DWI) of the spinal cord (SC) is problematic because of the small cross-section of the SC and the large field inhomogeneity. Obtaining the ultrahigh-b DWI poses a further challenge. The purpose of the study was to design and validate two-dimensional (2D) single-shot diffusion-weighted stimulated echo planar imaging with reduced field of view (2D ss-DWSTEPI-rFOV) for ultrahigh-b radial DWI (UHB-rDWI) of the SC.

Methods

A novel time-efficient 2D ss-DWSTEPI-rFOV sequence was developed based on the stimulated echo sequence. Reduced-phase field of view was obtained by using two slice-selective 90 math formula radiofrequency pulses in the presence of the orthogonal slice selection gradients. The sequence was validated on a cylindrical phantom and demonstrated on SC imaging.

Results

Ultrahigh-b radial diffusion-weighted ( math formula = 7300 math formula) images of the SC with greatly reduced distortion were obtained. The exponential plus constant fitting of the diffusion-decay curve estimated the constant fraction (restricted water fraction) as 0.36 ± 0.05 in the SC white matter.

Conclusion

A novel 2D ss-DWSTEPI-rFOV sequence has been designed and demonstrated for high-resolution UHB-rDWI of localized anatomic structures with significantly reduced distortion induced by nonlinear static field inhomogeneity. Magn Reson Med, 2016. © 2016 Wiley Periodicals, Inc.

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