Characterization of blood clot viscoelasticity by dynamic ultrasound elastography and modeling of the rheological behavior

Schmitt, Cédric; Henni, Anis Hadj; Cloutier, Guy

doi:10.1016/j.jbiomech.2010.11.015

Cited by 94 publications

(70 citation statements)

References 32 publications

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“…Such combinations of several modes and/or regions are not only common in many experiments, but also better resemble the physiological conditions in which these biomaterials are believed to operate. 41,42 Much like multiple relaxation time (MRT) models, SRT models are expected to correlate to a large extent with empirical data and may provide better assessments of viscoelastic properties than the Young's modulus alone, [43][44][45] with an advantage of avoiding the information redundancy commonly incurred by MRT models. SRT models may also facilitate the analysis of soft biomaterials, not as monolithic solids, but as a bundle of strings, each having the same elastic moduli and viscosity, but with different failure points, thereby enabling the modeling of such solids beyond their apparent linear viscoelastic region and into their failure region.…”

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confidence: 99%

A Mathematical Model for Analyzing the Elasticity, Viscosity, and Failure of Soft Tissue: Comparison of Native and Decellularized Porcine Cardiac Extracellular Matrix for Tissue Engineering

Bronshtein

Au-Yeung

Sarig

et al. 2013

Tissue Engineering Part C: Methods

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The clinical success of tissue-engineered constructs commonly requires mechanical properties that closely mimic those of the human tissue. Determining the viscoelastic properties of such biomaterials and the factors governing their failure profiles, however, has proven challenging, although collecting extensive data regarding their tensile behavior is straightforward. The easily calculated Young's modulus remains the most reported mechanical measure, regardless of its limitations, even though single-relaxation-time (SRT) models can provide much more information, which remain scarce due to a lack of manageable tools for implementing these models. We developed an easy-to-use algorithm for applying the Zener SRT model and determining the elastic moduli, viscosity, and failure profiles of materials under different mechanical tests in a user-independent manner. The algorithm was validated on the data resulting from tensile tests on native and decellularized porcine cardiac tissue, previously suggested as a promising scaffold material for cardiac tissue engineering. This analysis yields new and more accurate measurements such as the elastic moduli and viscosity, the model's relaxation time, and information on the factors governing the materials' failure profiles. These measurements indicate that the viscoelasticity and strength of the decellularized acellular extracellular matrix (ECM) are similar to those of native tissue, although its elasticity and apparent viscosity are higher. Nonetheless, reseeding and culturing the ECM with mesenchymal stem cells was shown to partially restore the mechanical properties lost after decellularization. We propose this algorithm as a platform for soft-tissue analysis that can provide comparable and unbiased measures for characterizing viscoelastic biomaterials commonly used in tissue engineering.

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confidence: 99%

A Mathematical Model for Analyzing the Elasticity, Viscosity, and Failure of Soft Tissue: Comparison of Native and Decellularized Porcine Cardiac Extracellular Matrix for Tissue Engineering

Bronshtein

Au-Yeung

Sarig

et al. 2013

Tissue Engineering Part C: Methods

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“…Henni et al did ultrasound elastography on a cuboidal gelatin phantom that had a soft cylindrical region running through it to validate their elegant analytic model of scattering and diffraction of a plane shear wave by an infinite cylinder [16]. Schmitt et al used Henni’s model to solve the inverse problem of characterizing vascular behavior with ultrasound elastography [17] [18]. Doyley et al constructed elastically heterogeneous phantoms by embedding hydrogel spheres in a hydrogel medium of a different stiffness from the spheres to show that more sophisticated mathematical assumptions, i.e.…”

Section: Introductionmentioning

confidence: 99%

Scattering and Diffraction of Elastodynamic Waves in a Concentric Cylindrical Phantom for MR Elastography

Schwartz

Yin

Yasar

et al. 2016

IEEE Trans. Biomed. Eng.

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Aim The focus of this paper is to report on the design and construction of a multiply connected phantom for use in magnetic resonance elasography (MRE)–an imaging technique that allows for the non-invasive visualization of the displacement field throughout an object from externally driven harmonic motion–as well as its inverse modeling with a closed-form analytic solution which is derived herein from first principles. Methods Mathematically, the phantom is described as two infinite concentric circular cylinders with unequal complex shear moduli, harmonically vibrated at the exterior surface in a direction along their common axis. Each concentric cylinder is made of a hydrocolloid with its own specific solute concentration. They are assembled in a multi-step process for which custom scaffolding was designed and built. A customized spin-echo based MR elastography sequence with a sinusoidal motion-sensitizing gradient was used for data acquisition on a 9.4 T Agilent small-animal MR scanner. Complex moduli obtained from the inverse model are used to solve the forward problem with a finite element method. Results Both complex shear moduli show a significant frequency dependence (p < 0.001) in keeping with previous work. Conclusion The novel multiply connected phantom and mathematical model are validated as a viable tool for MRE studies. Significance On a small enough scale much of physiology can be mathematically modeled with basic geometric shapes, e.g. a cylinder representing a blood vessel. This work demonstrates the possibility of elegant mathematical analysis of phantoms specifically designed and carefully constructed for biomedical MRE studies.

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“…Definitive calculations would be based on up-to-date methods such as a shear-wave approach; recent studies of blood clot properties have involved methods such as supersonic shear-wave imaging and shear-wave dispersion ultrasound vibrometry. 18–20 Such methods enable separate measurement of viscosity and elasticity as well as distinction between shear storage modulus and shear loss modulus. The accuracy with which absolute viscoelastic parameters can be measured with today’s thrombelastography and thromboelastometry devices could be investigated by comparing results obtained with TEG/ROTEM with those from up-to-date rheological methods, using a range of different blood samples.…”

Section: Introductionmentioning

confidence: 99%

Revisiting Hartert’s 1962 Calculation of the Physical Constants of Thrombelastography

Hochleitner¹,

Sutor²,

Levett³

et al. 2015

Clin Appl Thromb Hemost

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Thrombelastography (TEG)/thromboelastometry (ROTEM) devices measure viscoelastic clot strength as clot amplitude (A). Transformation of clot amplitude into clot elasticity (E with TEG; CE with ROTEM) is sometimes necessary (eg, when calculating platelet component of the clot). With TEG, clot amplitude is commonly transformed into shear modulus (G; expressed in Pa or dyn/cm2) as follows: G = (5000 × A)/(100 – A). Use of the constant “5000” stems from Hartert's 50-year-old calculation of G for a normal blood clot. We question the value of calculating G as follows: (1) It may be questioned whether TEG/ROTEM analysis enable measurement of elasticity because viscosity may also contribute to clot amplitude. (2) It has been suggested that absolute properties of a blood clot cannot be measured with TEG/ROTEM analysis because the strain amplitude applied by the device is uncontrolled and changes during the course of coagulation. (3) A review of the calculation of G using Hartert's methods and some updated assumptions suggests that the value of 5000 is unreliable. (4) Recalculation of G for the ROTEM device yields a different value from that with Hartert TEG, indicating a degree of inaccuracy with the calculations. (5) Shear modulus is simply a multiple of E/CE and, because of the unreliability of G in absolute terms, it provides no additional value versus E/CE. The TEG and ROTEM are valuable coagulation assessment tools that provide an evaluation of the viscoelastic properties of a clot, not through measuring absolute viscoelastic forces but through continuous reading of the clot amplitude relative to an arbitrary, preset scale.

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Characterization of blood clot viscoelasticity by dynamic ultrasound elastography and modeling of the rheological behavior

Cited by 94 publications

References 32 publications

A Mathematical Model for Analyzing the Elasticity, Viscosity, and Failure of Soft Tissue: Comparison of Native and Decellularized Porcine Cardiac Extracellular Matrix for Tissue Engineering

A Mathematical Model for Analyzing the Elasticity, Viscosity, and Failure of Soft Tissue: Comparison of Native and Decellularized Porcine Cardiac Extracellular Matrix for Tissue Engineering

Scattering and Diffraction of Elastodynamic Waves in a Concentric Cylindrical Phantom for MR Elastography

Revisiting Hartert’s 1962 Calculation of the Physical Constants of Thrombelastography

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