Dispersion and Shear Modulus Measurements of Porcine Liver

Orescanin, Marko; Qayyum, Muqeem A.; Toohey, Kathleen S.; Insana, Michael F.

doi:10.1177/016173461003200405

Cited by 24 publications

(12 citation statements)

References 37 publications

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“…It is noteworthy that the demonstration that leanness and undernutrition are determinants of LSM values in a healthy liver adds to the basic, as yet unresolved issue of putative contributors to the viscoelastic properties of a normal liver. Cellular components and scaffolding materials along with the influence of Glisson's capsule are more relevant in a healthy liver than collagen tissue as in fibrotic disease 32, 33. Although liver stiffness in pathological states correlates well with the degree of hepatic fibrosis, portal hypertension, passive venous congestion, extrahepatic cholestasis, and inflammation have also been described to increase LSM values 1, 34‐37.…”

Section: Discussionmentioning

confidence: 99%

“Normal” Liver Stiffness Measure (LSM) Values Are Higher in Both Lean and Obese Individuals: A Population-Based Study From a Developing Country

Sarkar

Ahmed

et al. 2012

Hepatology

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The liver stiffness measure (LSM) needs to be explored in ethnically and anthropometrically diverse healthy subjects (to derive an acceptable normal range) and also in patients with liver disease. In view of this objective, LSM was performed by transient elastography (TE) using FibroScan in 437 healthy subjects with normal alanine aminotransferase (ALT) levels, recruited from a free‐living population of the Birbhum Population Project (BIRPOP; http://www.shds.in), a Health and Demographic Surveillance System (HDSS), and from 274 patients with liver disease attending the Hepatology Clinic of the School of Digestive and Liver Diseases (SDLD; Institute of Post Graduate Medical Education & Research [IPGME&R], Kolkata, India) including 188 with nonalcoholic fatty liver disease (NAFLD) and 86 with chronic hepatitis of viral and other etiologies. Liver biopsy was performed in 125 patients. The range of normal values for LSM, defined by 5th and 95th percentile values in healthy subjects, was 3.2 and 8.5 kPa, respectively. Healthy subjects with a lower body mass index (BMI; < <18.5 kg/m2) had a higher LSM compared with subjects who had a normal BMI; this LSM value was comparable to that of obese subjects (6.05 ± 1.78 versus 5.51 ± 1.59 and 6.60 ± 1.21, P = 0.016 and 0.349, respectively). Liver disease patients without histologic fibrosis had significantly higher LSM values compared with healthy subjects (7.52 ± 5.49 versus 5.63 ± 1.64, P < 0.001). Among the histologic variables, stage of fibrosis was the only predictor for LSM. LSM did not correlate with inflammatory activity and ALT in both NAFLD and chronic hepatitis groups. Conclusion: LSM varies between 3.2 and 8.5 kPa in healthy subjects of South Asian origin. Both lean and obese healthy subjects have higher LSM values compared with subjects with normal BMI. Liver stiffness begins to increase even before fibrosis appears in patients with liver disease. (Hepatology 2012)

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Section: Discussionmentioning

confidence: 99%

“Normal” Liver Stiffness Measure (LSM) Values Are Higher in Both Lean and Obese Individuals: A Population-Based Study From a Developing Country

Sarkar

Ahmed

et al. 2012

Hepatology

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“…Titanium dioxide particles were added to increase the optical contrast inside the gel. Details of phantom construction can be found in [5]. Three samples of each concentration were measured to test the repeatability of the technique.…”

Section: B Gelatin Phantom Testsmentioning

confidence: 99%

Dynamic method of optical coherence elastography in determining viscoelasticity of polymers and tissues

Wang

Shemonski

Adie

et al. 2013

2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

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In this paper, we report on a novel quantitative elastography technique that combines optical coherence tomography (OCT) with acoustic radiation force (ARF) excitation to estimate the complex modulus. Sinusoidally modulated ARF excitations between 200 - 4000 Hz generate a surface wave at the tissue surface that can be related to bulk viscoelastic (VE) properties in a manner that is both precise and quantitative. This method is very well suited to studying media at high spatial resolution and over a very broad range of force frequencies. Mechanical characterization was calibrated using hydropolymers before studying liver samples. Fresh porcine liver samples were measured over time with and without formalin fixation. These data were used to evaluate the utility of the Kelvin-Voigt rheological model commonly used to fit dispersion data when estimating modulus values. We also investigated use of square-wave force excitation to measure the step response of tissues.

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“…These models are used to show the relationship between the stress and strain that models the viscoelastic response of tissue and its structure. The standard rheological models like, Maxwell [33], Kelvin-Voigt model [33, 34, 35, 36] and standard linear solid models [33] are the most applicable ones. Sloninsky, et al [37] described a model called fractional derivative to model the behavior of biological tissue with lower number of fit parameters [38].…”

Section: Introductionmentioning

confidence: 99%

Automated Compression Device for Viscoelasticity Imaging

Nabavizadeh

Kinnick

Bayat

et al. 2017

IEEE Trans. Biomed. Eng.

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Non-invasive measurement of tissue viscoelastic properties is gaining more attention for screening and diagnostic purposes. Recently, measuring dynamic response of tissue under a constant force has been studied for estimation of tissue viscoelastic properties in terms of retardation times. The essential part of such a test is an instrument that is capable of creating a controlled axial force and is suitable for clinical applications. Such a device should be lightweight, portable and easy to use for patient studies to capture tissue dynamics under external stress. In this paper we present the design of an automated compression device for studying the creep response of materials with tissue-like behaviors. The device can be used to apply a ramp-and-hold force excitation for a predetermined duration of time and it houses an ultrasound probe for monitoring the creep response of the underlying tissue. To validate the performance of the device, several creep tests were performed on tissue-mimicking phantoms and the results were compared against those from a commercial mechanical testing instrument. Using a second order Kelvin-Voigt model and surface measurement of the forces and displacements, retardation times T1 and T2 were estimated from each test. These tests showed strong agreement between our automated compression device and the commercial mechanical testing system, with an average relative error of 2.9% and 12.4 %, for T1 and T2 respectively. Also, we present the application of compression device to measure local retardation times for four different phantoms with different size and stiffness.

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Dispersion and Shear Modulus Measurements of Porcine Liver

Cited by 24 publications

References 37 publications

“Normal” Liver Stiffness Measure (LSM) Values Are Higher in Both Lean and Obese Individuals: A Population-Based Study From a Developing Country

“Normal” Liver Stiffness Measure (LSM) Values Are Higher in Both Lean and Obese Individuals: A Population-Based Study From a Developing Country

Dynamic method of optical coherence elastography in determining viscoelasticity of polymers and tissues

Automated Compression Device for Viscoelasticity Imaging

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