How preservation time changes the linear viscoelastic properties of porcine liver

Wex, Cora; Stoll, Anke; Fröhlich, M.; Arndt, Stephanie; Lippert, H.

doi:10.3233/bir-130632

Cited by 18 publications

(11 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, we draw a comprehensive perspective of broadband data for liver by drawing from five different sources and measurement methodologies. Figure 5 combines soft tissue data from Bilston (2018), Kiss et al (2004), Klatt et al (2010), Wex et al (2013), and Chatelin et al (2011) over four decades of frequency, and demonstrates that the shear elastic modulus follows a generally increasing power law across many decades of frequency. These power law relationships indicate structure extending across several decades of measurement scales.…”

Section: Published Datamentioning

confidence: 99%

Towards a consensus on rheological models for elastography in soft tissues

Parker¹,

Szabo²,

Holm³

2019

Phys. Med. Biol.

View full text Add to dashboard Cite

A rising wave of technologies and instruments are enabling more labs and clinics to make a variety of measurements related to tissue viscoelastic properties. These instruments include elastography imaging scanners, rheological shear viscometers, and a variety of calibrated stress-strain analyzers.From these many sources of disparate data, a common step in analyzing results is to fit the measurements of tissue response to some viscoelastic model. In the best scenario, this places the measurements within a theoretical framework and enables meaningful comparisons of the parameters against other types of tissues. However, there is a large set of established rheological models, even within the class of linear, causal, viscoelastic solid models, so which of these should be chosen? Is it simply a matter of best fit to a minimum mean squared error of the model to several data points? We argue that the long history of biomechanics, including the concept of the extended relaxation spectrum, along with data collected from viscoelastic soft tissues over an extended range of times and frequencies, and the theoretical framework of multiple relaxation models which model the multi-scale nature of physical tissues, all lead to the conclusion that fractional derivative models represent the most succinct and meaningful models of soft tissue viscoelastic behavior. These arguments are presented with the goal of clarifying some distinctions between, and consequences of, some of the most commonly used models, and with the longer term goal of reaching a consensus among different sub-fields in acoustics, biomechanics, and elastography that have common interests in comparing tissue measurements.

show abstract

Section: Published Datamentioning

confidence: 99%

Towards a consensus on rheological models for elastography in soft tissues

Parker¹,

Szabo²,

Holm³

2019

Phys. Med. Biol.

View full text Add to dashboard Cite

show abstract

“…However, the order of magnitude of the shear modulus retrieved from elastography and other measurement methods, such as dynamic mechanical analysis (DMA), differs [1]. Furthermore, ex vivo and in vivo elastography measurements vary, making a standardization difficult [2,3]. Finally, the observed in vivo shear wave velocity dispersion with frequency of the liver is badly predicted by visco-elastic theory, and recent in vivo studies [4,5] challenge the commonly assumed correlation of viscosity with fibrosis [6].…”

Section: Introductionmentioning

confidence: 99%

Fluids Alter Elasticity Measurements: Porous Wave Propagation Accounts for Shear Wave Dispersion in Elastography

Aichele

Catheline

2021

Front. Phys.

View full text Add to dashboard Cite

In shear wave elastography, rotational wave speeds are converted to elasticity measures using elastodynamic theory. The method has a wide range of applications and is the gold standard for non-invasive liver fibrosis detection. However, the observed shear wave dispersion of in vivo human liver shows a mismatch with purely elastic and visco-elastic wave propagation theory. In a laboratory phantom experiment we demonstrate that porosity and fluid viscosity need to be considered to properly convert shear wave speeds to elasticity in soft porous materials. We extend this conclusion to the clinical application of liver stiffness characterization by revisiting in vivo studies of liver elastography. To that end we compare Biot’s theory of poro-visco-elastic wave propagation to Voigt’s visco-elastic model. Our results suggest that accounting for dispersion due to fluid viscosity could improve shear wave imaging in the liver and other highly vascularized organs.

show abstract

“…Garo et al [42], Kerdok et al [43], Ocal et al [40], and Yarpuzlu et al [44] also observed that liver tissue becomes stiffer and more viscous as the post-mortem time increases. On the other hand, Wex et al [27] have recently reported that the complex shear modulus of liver tissue decreases with increasing post-mortem times.…”

Section: Discussionmentioning

confidence: 97%

“…The storage and loss moduli of liver tissue were reported to vary between GS=350-450 Pa and GL=70-90 Pa, respectively for the pre-strain value in the normal direction varying between 1-20%. Wex et al [27] performed strain (1 Hz, 0.0001-1% strain), stress (1 Hz, 0.1-100 Pa), and frequency sweeps (0.1-10 Hz, 0.001% shear strain) and relaxation experiments (1 Hz, 1 Pa, 600 s) on porcine liver using a rheometer. There are also studies in the literature reporting the dynamic elastic modulus of animal and human livers (Note that the linear elastic and shear moduli are related through E = 2G(1 + v) for homogenous and isotropic materials.…”

Section: Discussionmentioning

confidence: 99%

“…It is capable of representing both -time (relaxation, creep) and -frequency (dynamic oscillation) dependent behavior of liver tissue. This model has been successfully utilized by other researchers in the literature for representing the viscoelastic behavior of soft tissues [22,27,30]. The constitutive equations for KVFDM in time and frequency domains are given in Equation 5 and 6.…”

Section: Modelingmentioning

confidence: 99%

See 1 more Smart Citation

Effect of solution and post-mortem time on mechanical and histological properties of liver during cold preservation

2014

View full text Add to dashboard Cite

BACKGROUND:In liver transplantation, the donor and recipient are in different locations most of the time, and longer preservation periods are inevitable. Hence, the choice of the preservation solution and the duration of the preservation period are critical for the success of the transplant surgery. OBJECTIVE: In this study, we examine the mechanical and histological properties of the bovine liver tissue stored in Lactated Ringer's (control), HTK and UW solutions as a function of preservation period. METHODS:The mechanical experiments are conducted with a shear rheometer on cylindrical tissue samples extracted from 3 bovine livers and the change in viscoelastic material properties of the bovine liver is characterized using the fractional derivative Kelvin-Voigt Model. Also, the histological examinations are performed on the same liver samples under a light microscope. RESULTS:The results show that the preservation solution and period have a significant effect on the mechanical and histological properties of the liver tissue. The storage and loss shear moduli, the number of the apoptotic cells, the collagen accumulation, and the sinusoidal dilatation increase, and the glycogen deposition decreases as the preservation period is longer. CONCLUSIONS: Based on the statistical analyses, we observe that the liver tissue is preserved well in all three solutions for up to 11 h. After then, UW solution provides a better preservation up to 29 h. However, for preservation periods longer than 29 h, HTK is a more effective preservation solution based on the least amount of change in mechanical properties. On the other hand, the highest correlation between the mechanical and histological properties is observed for the liver samples preserved in UW solution.

show abstract

How preservation time changes the linear viscoelastic properties of porcine liver

Cited by 18 publications

References 38 publications

Towards a consensus on rheological models for elastography in soft tissues

Towards a consensus on rheological models for elastography in soft tissues

Fluids Alter Elasticity Measurements: Porous Wave Propagation Accounts for Shear Wave Dispersion in Elastography

Effect of solution and post-mortem time on mechanical and histological properties of liver during cold preservation

Contact Info

Product

Resources

About