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Viscoelastic Response (VisR) Imaging

Background

Viscoelastic Response (VisR) imaging, a non-ionizing and non-invasive ultrasonic imaging technology, used to estimate the viscoelastic properties of tissue. VisR is performed by exciting tissue with multiple acoustic radiation force (ARF) impulses. The resulting on-axis displacements over time are then captured, using standard ultrasonic motion tracking techniques, and fit to a one-dimensional mass-spring-damper (MSD) model. An animation of this procedure is shown in Figure 1.

 

Figure 1. Animation of VisR beam sequence. Points on the plot show samples and the black line represents the MSD model fit to the data.
Animation of VisR beam sequence. Red and blue points on the plot show measured displacements and the black line represents the MSD model fit to the data.

Using the parameters output from fitting the displacement profile to the MSD model, separate elasticity and viscosity values can be calculated that are relative to the applied ARF amplitude. These parameters are referred to as “Relative Elasticity” (RE) and “Relative Viscosity” (RV). Images of RE and RV can be formed spanning a lateral field of view to create a map of tissue properties.

Applications

VisR imaging is being applied to several areas of clinical research where tissue stiffness and viscosity provide insight into disease.

  • In breast cancer imaging, VisR-derived elasticity and viscosity maps may improve diagnostic accuracy by enhancing traditional elastogram-to-B-Mode (E/B) ratios used to distinguish malignant from benign lesions.
  • In kidney transplantation, VisR can noninvasively detect early signs of fibrosis or rejection by assessing mechanical anisotropy and regional stiffness differences in the renal cortex.
  • VisR has also been used to evaluate muscle anisotropy in Duchenne muscular dystrophy, where changes in elasticity and viscosity reflect disease-related degeneration.

Select Publications

  • M. M. Hossain and C. M. Gallippi, “Viscoelastic Response Ultrasound Derived Relative Elasticity and Relative Viscosity Reflect True Elasticity and Viscosity: In Silico and Experimental Demonstration,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control, vol. 67, no. 6, pp. 1102–1117, June 2020, doi: 10.1109/TUFFC.2019.2962789.
  • A. V. Phillips, C. M. Kuzmiak, G. Torres, and C. M. Gallippi, “VisR Ultrasound Improves Diagnosis of Breast Cancer by the Elastogram-to-B-Mode Ratio in a Blinded Reader Study,” IEEE Open J. Ultrason. Ferroelectr. Freq. Control, vol. 5, pp. 67–76, 2025, doi: 10.1109/OJUFFC.2025.3560585.
  • C. J. Moore et al., “In Vivo Viscoelastic Response (VisR) Ultrasound for Characterizing Mechanical Anisotropy in Lower-Limb Skeletal Muscles of Boys with and without Duchenne Muscular Dystrophy,” Ultrasound Med. Biol., vol. 44, no. 12, pp. 2519–2530, Dec. 2018, doi: 10.1016/j.ultrasmedbio.2018.07.004.
  • K. A. Yokoyama et al., “in vivo VisR Measurements of Viscoelasticity and Viscoelastic Anisotropy in Human Allografted Kidneys Differentiate Interstitial Fibrosis and Graft Rejection,” in 2022 IEEE International Ultrasonics Symposium (IUS), Oct. 2022, pp. 1–4. doi: 10.1109/IUS54386.2022.9958358.