Tissue Biomechanics and the Microchannel Flow Model

Recent advances have enabled a new wave of biomechanics measurements, and have renewed interest in selecting appropriate rheological models for soft tissues such as the liver, thyroid, and prostate. The microchannel flow model was recently introduced to describe the linear response of tissue to stimuli such as stress relaxation or shear wave propagation. This model postulates a power law relaxation spectrum that results from a branching distribution of vessels and channels in normal soft tissue such as liver. In this work, the derivation is extended to determine the explicit link between the distribution of vessels and the relaxation spectrum. The microchannel flow model explains the dramatic changes in tissue “stiffness” caused by changes in the vasculature, including rapid vasodilation or vasoconstriction.

A microchannel flow model for soft tissue elasticity
K. J. Parker
Phys Med Biol, vol. 59, no. 15, pp. 4443-4457 (2014). View Online

Journal Articles

  1. Mouse brain elastography changes with sleep-wake cycles, aging, and Alzheimer's disease
    G. R. Ge, W. Song, M. J. Giannetto, J. P. Rolland, M. Nedergaard, and K. J. Parker
    NeuroImage, vol. 295 , pp. 120662-1 -120662-10  (2024). View PDF
  2. Brain elastography in aging relates to fluid-solid trendlines
    K. J. Parker, I. E. Kabir, M. M. Doyley, A. Faiyaz, M. N. Uddin, and G. Schifitto
    Phys Med Biol 69(11) , pp. 115037-1 -115037-16  (2024). View PDF
  3. Limitations of curl and directional filters in elastography
    K. J. Parker
    Acoustics, vol. 5, no. 2 , pp. 575 -585  (2023). View PDF
  4. Fluid compartments influence elastography of the aging mouse brain
    G. R. Ge, J. P. Rolland, W. Song, M. Nedergaard, and K. J. Parker
    Phys Med Biol, vol 68, no. 9 , pp. 095004-1 -095004-10  (2023). View PDF
  5. Theory of sleep-wake cycles affecting brain elastography
    G. R. Ge, W. Song, M. Nedergaard, J. P. Rolland, and K. J. Parker
    Phys Med Biol, vol. 67, no. 22 , pp. 225013-1 -225013-16  (2022). View PDF
  6. Comprehensive experimental assessments of rheological models’ performance in elastography of soft tissues
    S. S. Poul, J. Ormachea, G. R. Ge, and K. J. Parker
    Acta Biomaterialia, vol. 146 , pp. 259 -273  (2022). View PDF
  7. A preliminary study of liver fat quantification using reported ultrasound speed of sound and attenuation parameters
    J. Ormachea and K. J. Parker
    Ultrasound Med Biol, vol. 48, no. 4 , pp. 675 -684  (2022). View PDF
  8. The quantification of liver fat from wave speed and attenuation
    K. J. Parker and J. Ormachea
    Phys Med Biol, vol. 66, no. 14 , pp. 145011-1 -145011-10  (2021). View PDF
  9. Fat and fibrosis as confounding cofactors in viscoelastic measurements of the liver
    S. S. Poul and K. J. Parker
    Phys Med Biol, vol. 66, no. 4 , pp. 04524-1 -04524-14  (2021). View PDF
  10. Comprehensive viscoelastic characterization of tissues and the inter-relationship of shear wave (group and phase) velocity, attenuation and dispersion
    J. Ormachea and K. J. Parker
    Ultrasound Med Biol, vol. 46, no. 12 , pp. 3448 -3459  (2020). View PDF
  11. Validations of the microchannel flow model for characterizing vascularized tissues
    S. S. Poul, J. Ormachea, S. J. Hollenbach, and K. J. Parker
    Fluids, vol. 5, no. 4 , pp. 228-1 -228-14  (2020). View PDF
  12. Towards a consensus on rheological models for elastography in soft tissues
    K. J. Parker, T. Szabo, and S. Holm
    Phys Med Biol, vol. 64, no. 21 , pp. 215012-1 -215012-17  (2019). View PDF
  13. Attenuation of shear waves in normal and steatotic livers
    A. K. Sharma, J. Reis, D. C. Oppenheimer, D. J. Rubens, J. Ormachea, Z. Hah, and K. J. Parker
    Ultrasound Med Biol, vol. 45, no. 4 , pp. 895 -901  (2019). View PDF
  14. Shear wave propagation in viscoelastic media: validation of an approximate forward model
    F. Zvietcovich, N. Baddour, J. P. Rolland, and K. J. Parker
    Phys Med Biol, vol. 64, no. 2 , pp. 025008-1 -025008-13  (2019). View PDF
  15. Group versus phase velocity of shear waves in soft tissues
    K. J. Parker, J. Ormachea, and Z. Hah
    Ultrason Imaging, vol. 40, no. 6 , pp. 343 -356  (2018). View PDF
  16. The biomechanics of simple steatosis and steatohepatitis
    K. J. Parker, J. Ormachea, M. G. Drage, H. Kim, and Z. Hah
    Phys Med Biol, vol. 63, no. 10 , pp. 105013-1 -105013-11  (2018). View PDF
  17. Analysis of transient shear wave in lossy media
    K. J. Parker, J. Ormachea, S. Will, and Z. Hah
    Ultrasound Med Biol, vol. 44, no. 7 , pp. 1504 -1515  (2018). View PDF
  18. Are rapid changes in brain elasticity possible?
    K. J. Parker
    Physics in Medicine and Biology, vol. 62, no. 18 , pp. 7425 -7439  (2017). View Online
  19. The microchannel flow model under shear stress and high frequencies
    K. J. Parker
    Physics in Medicine and Biology, vol. 62, no. 8 , pp. N161 -N167  (2017). View Online
  20. Shear wave dispersion behaviors of soft, vascularized tissues from the microchannel flow, model
    K. J. Parker, J. Ormachea, S. A. McAleavey, R. W. Wood, J. J. Carroll-Nellenback, and R. K. Miller
    Physics in Medicine and Biology, vol. 61, no. 13 , pp. 4890 -4903  (2016). View Online
  21. Biological effects of low frequency strain: physical descriptors
    E. L. Carstensen, K. J. Parker, D. Dalecki, and D. Hocking
    Ultrasound in Medicine and Biology, vol. 42, no. 1 , pp. 1 -15  (2016). View Online
  22. Oestreicher and elastography
    E. L. Carstensen and K. J. Parker
    Journal of the Acoustical Society of America, vol. 138, no. 4 , pp. 2317 -2325  (2015). View PDF
  23. Shear wave dispersion in lean versus steatotic rat livers
    C. T. Barry, C. Hazard, Z. Hah, G. Cheng, A. Partin, R. A. Mooney, K. Chuang, and W. Cao
    Journal of Ultrasound in Medicine, vol. 34, no. 60 , pp. 1123 -1129  (2015). View Online
  24. What do we know about shear wave dispersion in normal and steatotic livers?
    K. J. Parker, A. Partin, and D. J. Rubens
    Ultrasound in Medicine and Biology, vol. 41, no. 5 , pp. 1481 -1487  (2015). View Online
  25. Experimental evaluations of the microchannel flow model
    K. J. Parker
    Physics in Medicine and Biology, vol. 60, no. 11 , pp. 4227 -4242  (2015). View Online
  26. Could linear hysteresis contribute to shear wave losses in tissues?
    K. J. Parker
    Ultrasound in Medicine and Biology, vol. 41, no. 4 , pp. 1100 -1104  (2015). View PDF
  27. A microchannel flow model for soft tissue elasticity
    K. J. Parker
    Phys Med Biol, vol. 59, no. 15 , pp. 4443 -4457  (2014). View Online
  28. Real and causal hysteresis elements
    K. J. Parker
    Journal of the Acoustical Society of America, vol. 135, no. 6 , pp. 3381 -3389  (2014). View Online
  29. Physical models of tissue in shear fields
    E. L. Carstensen and K. J. Parker
    Ultrasound in Medicine and Biology, vol. 40, no. 4 , pp. 655 -674  (2014). View Online
  30. Mouse liver dispersion for the diagnosis of early-stage fatty liver disease: a 70-sample study
    C. T. Barry, Z. Hah, A. Partin, R. A. Mooney, K. Chuang, A. Augustine, A. Almudevar, W. Cao, D. J. Rubens, and K. J. Parker
    Ultrasound in Medicine and Biology, vol. 41, no. 4 , pp. 704 -713  (2014). View Online
  31. The Guassian shear wave in a dispersive medium
    K. J. Parker and N. Baddour
    Ultrasound in Medicine and Biology, vol. 40, no. 4 , pp. 675 -684  (2014). View Online
  32. Shear wave dispersion measures liver steatosis
    C. T. Barry, B. Mills, Z. Hah, R. A. Mooney, C. K. Ryan, D. J. Rubens, and K. J. Parker
    Ultrasound Med Biol, vol. 38, no. 2 , pp. 175 -182  (2012). View Online
  33. Congruence of imaging estimators and mechanical measurements of viscoelastic properties of soft tissues
    M. Zhang, B. Castaneda, Z. Wu, P. Nigwekar, J. Joseph, D. J. Rubens, and K. J. Parker
    Ultrasound Med Biol, vol. 33, no. 10 , pp. 1617 -1631  (2007). View PDF