The Orientation of Orthopaedic Metallic Devices Relative to the Frequency-Encoding Gradient Affects Susceptibility Artifacts : An Experiment Using Open MR Imaging

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  • Takeuchi Naohide
    Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University
  • Mitsuyasu Hiromichi
    Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University
  • Nakanishi Tomonori
    Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University
  • Nishimura Sumako
    Clinical Application Department Marketing Division, Hitachi Medical Co. Ltd.
  • Shimoto Takeshi
    Department of Biorobotics, Faculty of Engineering, Kyushu Sangyo University
  • Higaki Hidehiko
    Department of Biorobotics, Faculty of Engineering, Kyushu Sangyo University
  • Hashizume Makoto
    Department of Advanced Medical Initiatives, Faculty of Medical Sciences, Kyushu University
  • Iwamoto Yukihide
    Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University

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Other Title
  • 大腿骨近位部骨折用髄内釘の金属方向と周波数エンコード傾斜磁場の方向は, 磁化率アーチファクトの出現に影響を与える : open MRI を用いた検討（英文）

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Abstract

To evaluate the magnetic susceptibility artifacts associated with different frequency-encoding gradient directions for an angled cephalomedullary device of the proximal femur, and to determine the optimal extremity positioning for reducing artifacts using 0.4 T open MR imaging. Materials and methods : Two different angular devices made of titanium alloy and stainless steel were used. The images were obtained with the frequency-encoding gradient parallel to the rod (Group R) and parallel to the lag screw (Group L). The device positioning was altered in order to obtain images with frequency-encoding gradient parallel to the rod and parallel to the lag screw. The artifact areas associated with the whole device and the lag screw were statistically evaluated. Results : For both devices, the mean artifact area in GroupLwas significantly larger than that in Group R (p < 0.05). However, the mean artifact area of the lag screw only in Group L was significantly smaller than that in Group R (p < 0.05). Conclusion : Susceptibility artifacts for angled cephalomedullary devices can be minimized when the frequency encoding gradient is parallel to the long axis of the regions of interest. Open MR imaging enables us to obtain the optimal orientation for minimizing susceptibility artifacts.

Journal

  • 福岡醫學雜誌

    福岡醫學雜誌 102 (5), 185-194, 2011-05-25

    Fukuoka Medical Association

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