In vivo bone and cartilage MRI using fully-balanced steady-state free-precession at 7 tesla

Authors

  • Roland Krug,

    Corresponding author
    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
    • QB3 Building, 2nd floor, #203, 1700-4th Street, San Francisco, CA 94143-2520
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  • Julio Carballido-Gamio,

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
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  • Suchandrima Banerjee,

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
    2. University of California, San Francisco–University of California, Berkeley Joint Graduate Group in Bioengineering, San Francisco–Berkeley, California, USA
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  • Robert Stahl,

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
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  • Lucas Carvajal,

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
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  • Duan Xu,

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
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  • Dan Vigneron,

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
    2. University of California, San Francisco–University of California, Berkeley Joint Graduate Group in Bioengineering, San Francisco–Berkeley, California, USA
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  • Douglas A.C. Kelley,

    1. GE Healthcare Technologies, San Francisco, California, USA
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  • Thomas M. Link,

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
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  • Sharmila Majumdar

    1. Department of Radiology, University of California, San Francisco, San Francisco, California, USA
    2. University of California, San Francisco–University of California, Berkeley Joint Graduate Group in Bioengineering, San Francisco–Berkeley, California, USA
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Abstract

The purpose of this work was to investigated the feasibility of fully-balanced steady-state free-precession (bSSFP) pulse sequence for trabecular bone and knee cartilage imaging in vivo using ultra-high-field (UHF) MRI at 7T in comparison with pulse sequences previously used at 3T. We showed that bSSFP and spin-echo imaging is possible at higher field strengths within 3.2 W/kg specific absorption rate (SAR) constraints. All pulse sequences were numerically optimized based on measured tissue relaxation parameters from six healthy volunteers (T1 = 820 ± 128 ms, T2 = 43.5 ± 3 ms for bone marrow and T1 = 1745 ± 104 ms and T2 = 30 ± 4 ms for cartilage). From simulations of the Bloch equation, a signal-to-noise ratio (SNR) increase of more than 1.9 was predicted. Cartilage SNR of bSSFP was 2.4 times higher at 7T (51.3 ± 4.3) compared with 3T (21.3 ± 3.3). Bone SNR increased from 11.8 ± 2.0 to 13.2 ± 2.5 at the higher field strength. We concluded that there is SNR benefit and great potential for bone and cartilage imaging at higher field strength. Magn Reson Med, 2007. © 2007 Wiley-Liss, Inc.

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