Excitation System for Magnetic Resonance Elastography Using Micro MRI

DOI Web Site 被引用文献5件 参考文献1件
  • TADANO Shigeru
    Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
  • FUJISAKI Kazuhiro
    Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
  • SUZUKI Hayato
    Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
  • TAKAO Seishin
    Cooperative Department of Medical Physics and Engineering, Graduate School of Medicine, Hokkaido University
  • SUGA Mikio
    Department of Medical System Engineering, Faculty of Engineering, Chiba University
  • KAJIWARA Itsuro
    Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
  • YAMAMOTO Toru
    Division of Biomedical Science and Engineering, Faculty of Health Science, Hokkaido University
  • JIANG Yu
    Department of Mathematics, Faculty of Science, Hokkaido University
  • NAKAMURA Gen
    Department of Mathematics, Faculty of Science, Hokkaido University

抄録

Magnetic resonance elastography (MRE) is a nondestructive method for measuring the hardness and softness of living tissue by means of magnetic resonance imaging (MRI) coupled with mechanical excitation of the subject. The shear modulus of a tissue is related to the velocity of transverse waves propagating through it, and local movements are obtained from MRI phase images. Micro MRI systems are available for high-resolution MRE measurements of soft materials. Longitudinal waves are effective for long-distance wave propagation from small excitation areas in micro MRI systems, and the transverse waves produced by the longitudinal waves can be used for elastography. This study proposes an excitation system comprising a high-power vibration generator and bar-shaped vibration transmitter made from an elastic material. The transmission characteristics of the glass-fiber-reinforced plastic bar-shaped transducer were evaluated by measuring the accelerations at its base and tip. The performance of the excitation system, which focused on the effects of frequency and amplitude, was investigated for measuring storage and loss modulus distributions in agarose gel. This system could transfer longitudinal waves with an amplitude of 0.5 mm and frequency between 50 and 250 Hz, without significant damping. Moreover, the excitation capabilities for gel phantoms were evaluated by MRE using 0.3T micro MRI equipment. A large amplitude of 0.5 mm and high frequency of 250 Hz produced less data scatter than smaller amplitudes and lower frequencies. MRE performance improved upon using strong excitations.

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