Ex vivo bovine liver nonlinear viscoelastic properties: MR elastography and rheological measurements

Jugé, Lauriane; Foley, Patrick; Hatt, Alice; Yeung, Jade; Bilston, Lynne E.

doi:10.1016/j.jmbbm.2022.105638

“…Regarding the shear wave propagation and the polarization selected, it is observed an increase or a decrease of the shear modulus relatively to the applied stress. In previous MRE studies assessing tissue stiffness under compression, on an increase in stiffness was observed during compression (Page et al 2019, Jugé et al 2023. However, in these studies mechanical parameters obtained in each encoding direction were averaged and shear wave propagation was not filtered along a single direction.…”

Section: Discussionmentioning

confidence: 99%

“…As previously demonstrated, MRE is able to assess the evolution of ex vivo and in vivo tissue mechanical properties under compression (Clarke et al 2011, Page et al 2019. Based on these works, Jugé et al recently showed that MRE can be used as a reliable technique to estimate nonlinear viscoelastic properties of the liver (Jugé et al 2023). Therefore, using appropriate conditions it should be possible to estimate nonlinear shear modulus with acoustoelasticity in MRE.…”

mentioning

confidence: 98%

Comparison of ultrasound elastography, magnetic resonance elastography and finite element model to quantify nonlinear shear modulus

Pagé,

Bied,

Garteiser

et al. 2023

Phys. Med. Biol.

1

0

View full text Add to dashboard Cite

Objective. The aim of this study is to validate the estimation of the nonlinear shear modulus ( A ) from the acoustoelasticity theory with two experimental methods, ultrasound (US) elastography and magnetic resonance elastography (MRE), and a finite element method. Approach. Experiments were performed on agar (2%)—gelatin (8%) phantom considered as homogeneous, elastic and isotropic. Two specific setups were built to ensure a uniaxial stress step by step on the phantom, one for US and a nonmagnetic version for MRE. The stress was controlled identically in both imaging techniques, with a water tank placed on the top of the phantom and filled with increasing masses of water during the experiment. In US, the supersonic shear wave elastography was implemented on an ultrafast US device, driving a 6 MHz linear array to measure shear wave speed. In MRE, a gradient-echo sequence was used in which the three spatial directions of a 40 Hz continuous wave displacement generated with an external driver were encoded successively. Numerically, a finite element method was developed to simulate the propagation of the shear wave in a uniaxially stressed soft medium. Main results. Similar shear moduli were estimated at zero stress using experimental methods, μ 0 U S = 12.3 ± 0.3 kPa and μ 0 M R E = 11.5 ± 0.7 kPa. Numerical simulations were set with a shear modulus of 12 kPa and the resulting nonlinear shear modulus was found to be −58.1 ± 0.7 kPa. A very good agreement between the finite element model and the experimental models ( A U S = −58.9 ± 9.9 kPa and A M R E = −52.8 ± 6.5 kPa) was obtained. Significance. These results show the validity of such nonlinear shear modulus measurement quantification in shear wave elastography. This work paves the way to develop nonlinear elastography technique to get a new biomarker for medical diagnosis.

show abstract

“…Therefore, it has become crucial to develop a robust methodological approach for characterizing the viscoelastic properties of soft biological tissues and hydrogels. In clinical scenarios, several approaches have been developed for assessing the stiffness and viscoelasticity of biological tissues in a non-invasive way, including ultrasound elastography [26][27][28][29], magnetic resonance elastography (MRE) [30,31], and optical coherence elastography (OCE) [32][33][34]. On the other hand, in experimental lab settings, techniques such as tensile and compression testing [35,36], dynamic mechanical analysis (DMA), and nanoindentation [11,[37][38][39][40] have been adopted to quantitatively characterize the viscoelastic behaviors of biological soft tissues and hydrogels.…”

Section: Introductionmentioning

confidence: 99%

A Methodological Approach for Interpreting and Comparing the Viscoelastic Behaviors of Soft Biological Tissues and Hydrogels at the Cell-Length Scale

Tosini,

Tänzer,

Villata

et al. 2024

Applied Sciences

1

0

View full text Add to dashboard Cite

The behavior of a cell is strongly influenced by the physical properties and stimuli in its microenvironment. Furthermore, the activation and modulation of mechanotransduction pathways are involved in tissue development and homeostasis and even pathological processes. Thus, when developing materials aimed at mimicking the extracellular matrixes of healthy or pathological tissues, their mechanical features should be closely considered. In this context, nanoindentation represents a powerful technique for mechanically characterizing biological tissues and hydrogels at the cell-length scale. However, standardized experimental protocols and data analysis techniques are lacking. Here, we proposed a methodological approach based on the nanoindentation technique for quantitatively analyzing and comparing the time-dependent load relaxation responses of soft biological tissues and hydrogels. As this was an explanatory study, stress-relaxation nanoindentation tests were performed on samples of pig and human lung tissues and of a specific gelatin-methacryloyl (GelMA) hydrogel to quantify and compare their viscoelastic properties. The proposed method allowed for identifying the characteristic parameters needed for describing the behavior of each sample, permitting us to quantitatively compare their mechanical behaviors. All samples showed load relaxation at a defined indentation depth because of their intrinsic viscoelastic behaviors, and the GelMA samples showed the highest relaxation capabilities. The distribution of the characterization parameters showed that the biological samples presented similar time-dependent responses, while differences were observed in the GelMA samples. Overall, the proposed methodological approach allows for providing key insights into the time-dependent behaviors of soft biological tissues and hydrogels at the cell-length scale in view of supporting tissue engineering and pathophysiological investigations.

show abstract

“…Measuring the mechanical properties of soft tissues is challenging due to their malleability, requiring specialized devices [2,13,14]. Rheology is commonly employed to assess these properties, focusing on viscoelastic characteristics in tissues like the brain [10,[15][16][17], liver [18][19][20][21], kidney [21,22], and muscle [23]. Oscillatory rheology efficiently measures a sample's storage modulus (S mod ), loss modulus (L mod ), and complex shear modulus (CS mod ).…”

Section: Introductionmentioning

confidence: 99%

The influence of cooling on biomechanical time since death estimations using ovine brain tissue

Zwirner,

Devananthan,

Docherty

et al. 2024

Int J Legal Med

0

View full text Add to dashboard Cite

The significance of biomechanical analyses for forensic time since death estimations has recently been demonstrated. Previous biomechanical analyses successfully discriminated post-mortem brain tissue from tissue with a post-mortem interval of at least one day when held at 20 °C. However, the practical utility of such analyses beyond day one at 20 °C was limited. This study investigates the storage, loss, and complex shear modulus of various brain regions in sheep stored at 4 °C in 24-hour intervals over four days post-mortem using rheometry tests. The aim is to identify the critical biomechanical tissue property values to predict post-mortem time and assess the temperature sensitivity of the rheometry method by comparing results to recent findings at 20 °C. Thirty sheep brains were examined, including the frontal lobe, parietal lobe, anterior and posterior deep brain, superior colliculi, pons, medulla, and cerebellum. Rheometry tests were conducted, and receiver operator characteristic analyses were employed to establish cut-off values. At 4 °C storage, all investigated biomechanical properties of the examined brain regions remained stable for at least one day post-mortem. Using cerebellar samples stored at 4 °C, a post-mortem interval of at least two days could be determined with excellent diagnostic ability. Complex shear modulus values below 1435 Pa or storage modulus values below 1313 Pa allowed prediction of two or more days post-mortem. Comparisons between 4 °C and 20 °C revealed brain region-specific results. For instance, the complex shear moduli of the anterior deep brain at 4 °C were significantly higher on all individual testing days when compared to 20 °C. In contrast, the combined medulla and pons samples were similar on each day. Rheometry testing of brain tissue consistently stored at 4 °C since death proved valuable for forensic time since death estimations starting from two days after death.

show abstract

Ex vivo bovine liver nonlinear viscoelastic properties: MR elastography and rheological measurements

Cited by 4 publications

References 55 publications

Comparison of ultrasound elastography, magnetic resonance elastography and finite element model to quantify nonlinear shear modulus

Comparison of ultrasound elastography, magnetic resonance elastography and finite element model to quantify nonlinear shear modulus

A Methodological Approach for Interpreting and Comparing the Viscoelastic Behaviors of Soft Biological Tissues and Hydrogels at the Cell-Length Scale

The influence of cooling on biomechanical time since death estimations using ovine brain tissue

Contact Info

Product

Resources

About