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Parker Medical Imaging Research

The Reverberant Shear Wave Fields

The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. However, multiple reflections from organ boundaries and internal inhomogeneities and mode conversions can create a complicated field in time and space. Thus, we derived the mathematics of multiple component shear wave fields and derive the basic properties from which efficient estimators can be obtained. We approached this problem from the historic perspective of reverberant fields, a conceptual framework used in architectural acoustics and related fields. The framework can be recast for the alternative case of shear waves in a bounded elastic media, and the expected value of displacement patterns in shear reverberant fields have been derived, along with some practical estimators of shear wave speed. These results open up the possibility of faster elastography imaging in deeper tissues, with high accuracy.

Journal Articles

  1. Shear wave speed estimation using reverberant shear wave fields: implementation and feasibility studies
    J. Ormachea, B. Castaneda, and K. J. Parker
    Ultrasound Med Biol, vol. 44, no. 5 , pp. 963 -977  (2018). View PDF
  2. Reverberant shear wave fields and estimation of tissue properties
    K. J. Parker, J. Ormachea, F. Zvietcovich, and B. Castaneda
    Physics in Medicine and Biology, vol. 62, no. 3 , pp. 1046 -1061  (2017). View Online