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Radiology and imaging
Research
Measuring shear-wave speed with point shear-wave elastography and MR elastography: a phantom study
  1. Riwa Kishimoto1,
  2. Mikio Suga2,
  3. Atsuhisa Koyama2,
  4. Tokuhiko Omatsu1,
  5. Yasuhiko Tachibana1,
  6. Daniel K Ebner1,
  7. Takayuki Obata1
  1. 1Hospital of the National Institute of Radiological Sciences, National Institutes of Quantum and Radiation Science and Technology, Chiba, Japan
  2. 2Center for Frontier Medical Engineering, Chiba University, Chiba, Japan
  1. Correspondence to Dr Riwa Kishimoto; kishimoto.riwa{at}qst.go.jp

Abstract

Objectives To compare shear-wave speed (SWS) measured by ultrasound-based point shear-wave elastography (pSWE) and MR elastography (MRE) on phantoms with a known shear modulus, and to assess method validity and variability.

Methods 5 homogeneous phantoms of different stiffnesses were made. Shear modulus was measured by a rheometer, and this value was used as the standard. 10 SWS measurements were obtained at 4 different depths with 1.0–4.5 MHz convex (4C1) and 4.0–9.0 MHz linear (9L4) transducers using pSWE. MRE was carried out once per phantom, and SWSs at 5 different depths were obtained. These SWSs were then compared with those from a rheometer using linear regression analyses.

Results SWSs obtained with both pSWE as well as MRE had a strong correlation with those obtained by a rheometer (R2>0.97). The relative difference in SWS between the procedures was from −25.2% to 25.6% for all phantoms, and from −8.1% to 6.9% when the softest and hardest phantoms were excluded. Depth dependency was noted in the 9L4 transducer of pSWE and MRE.

Conclusions SWSs from pSWE and MRE showed a good correlation with a rheometer-determined SWS. Although based on phantom studies, SWSs obtained with these methods are not always equivalent, the measurement can be thought of as reliable and these SWSs were reasonably close to each other for the middle range of stiffness within the measurable range.

  • elastography
  • shear wave
  • rheometer
  • acoustic radiation force impulse

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjopen-2016-013925

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    Footnotes

    • Contributors RK, MS, AK and TO provided substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work. RK, MS, AK, DKE and TO were involved in drafting the work or revising it critically for important intellectual content. All authors were involved in final approval of the version to be published and provided agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

    • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement No additional data are available.