Congruence of Imaging Estimators and Mechanical Measurements of Viscoelastic Properties of Soft Tissues

Abstract

Biomechanical properties of soft tissues are important for a wide range of medical applications, such as surgical simulation and planning and detection of lesions by elasticity imaging modalities. Currently, the data in the literature is limited and conflicting. Furthermore, to assess the biomechanical properties of living tissue in vivo, reliable imaging-based estimators must be developed and verified. For these reasons we developed and compared two independent quantitative methods -crawling wave estimator (CRE) and mechanical measurement (MM) for soft tissue characterization. The CRE method images shear wave interference patterns from which the shear wave velocity can be determined and hence the Young's modulus can be obtained. The MM method provides the complex Young's modulus of the soft tissue from which both elastic and viscous behavior can be extracted. This article presents the systematic comparison between these two techniques on the measurement of gelatin phantom, veal liver, thermal-treated veal liver, and human prostate. It was observed that the Young's moduli of liver and prostate tissues slightly increase with frequency. The experimental results of the two methods are highly congruent, suggesting CRE and MM methods can be reliably used to investigate viscoelastic properties of other soft tissues, with CRE having the advantages of operating in nearly real time and in situ.

Real‐time sonoelastography of hepatic thermal lesions in a swine model

“…The Young's moduli of RFA lesions, HIFU lesions, and untreated tissues were 187Ϯ 32 kPa, 143Ϯ 34 kPa, and 10Ϯ 3 kPa at vibration frequencies ͑100-200 Hz͒, respectively. These results are consistent with the data reported by our earlier study 42 and other groups. [45][46][47] …”

Generalized response of a sphere embedded in a viscoelastic medium excited by an ultrasonic radiation force

“…15 Last, the Kelvin-Voigt fractional derivative model was used to characterize various gelatin phantoms and ex vivo veal livers and ex vivo human prostates. 13 These results demonstrate that the viscoelastic behavior of tissue can be fit using different rheological models for characterization.…”

“…For characterization of viscoelastic materials many other rheological models exist, including the Maxwell, KelvinVoigt, generalized Maxwell (GM) model, the Zener model (also known as the standard linear solid), and the KelvinVoigt fractional derivative (KVFD) model, but those previously mentioned are commonly used, particularly in characterizing soft tissues. [9][10][11][12][13][14][15] These rheological models have been used to characterize different soft tissues with varying degrees of sensitivity. The Kelvin-Voigt model has been used extensively in the viscoelastic characterization of tissue because of its simplicity and intuitive separation of elastic and viscous effects.…”

Review of ultrasound elastography quality control and training test phantoms

“…Table 2 presents a list of suggested tissue mimicking properties matched to specific clinical applications, based on measured mechanical properties reported in a number of clinical studies. 11,[38][39][40][41][42][43][44][45][46][47][48] The background properties are usually representative of the approximate stiffness values of the healthy tissue in the respective clinical application, while the range of the target stiffness usually represents the typical values of malignant lesions. The minimum target dimensions seem to reflect the minimum lesion dimensions detected in the studies, while the elastic contrast is the ratio of the stiffness of the target to that of the background material.…”