In vivo mechanical characterization of human liver

Nava, Alessandro; Mazza, Edoardo; Furrer, M.; Villiger, Peter M.; Reinhart, Walter H.

doi:10.1016/j.media.2007.10.001

Cited by 193 publications

(156 citation statements)

References 28 publications

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“…5 The flow chart of our inverse finite element solution for estimating the hyper-viscoelastic material coefficients of pig liver [15] measurements are very limited. Most of the earlier studies have focused on the characterization of static and viscoelastic material properties of animal [2,4,14,15,18] and human livers [10], but not their frequency-dependent properties. Saraf et al [17] investigated the dynamic response of human liver in hydrostatic compression and simple shear using the Kolsky bar technique at high strain rates ranging from 300 to 5000 s .…”

Section: Review Of the Literaturementioning

confidence: 99%

Dynamic Material Properties of Human and Animal Livers

Başdoğan

2012

Studies in Mechanobiology, Tissue Engineering and Biomaterials

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Accurate characterization of the mechanical properties of soft tissues is important for diagnosing medical pathologies and developing solutions for them. With the recent advances in technologies leading to the development of surgical simulators, medical robots, and computer-assisted surgical planning systems, this topic has gained even more importance. However, most of the earlier research studies conducted with animal and human livers have focused on the investigation of static (strain-dependent) material properties. The number of studies investigating the dynamic material properties (time and frequency-dependent) of animal and human livers are much less than the ones investigating the static material properties. In fact, there is almost no data available in the literature showing the variation in dynamic material properties of healthy or diseased human liver as a function of excitation frequency. MotivationSoft organ tissues exhibit complex nonlinear, anisotropic, non-homogeneous, time, and rate-dependent behavior. Fung [1] has revealed that nonlinear stress-strain relationship is common for soft tissues but the degrees are different for different tissues. Since soft organs are composed of different materials, like elastin and collagen, in different combinations, soft tissue properties are both coordinate and direction dependent. Time and rate dependent behavior is also common and explained by viscoelasticity.

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Section: Review Of the Literaturementioning

confidence: 99%

Dynamic Material Properties of Human and Animal Livers

Başdoğan

2012

Studies in Mechanobiology, Tissue Engineering and Biomaterials

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“…Very few suction devices were developed and evaluated for tissues that are only reachable during surgery. To our knowledge, only the suction device of Vuskovic [9] was tested on the uterine cervix during surgery and more recently on the liver [13]. This is probably due to the rather drastic sterilization process needed for each ancillary that has to be used in the sterile field of the operation theater.…”

Section: In Vivo Devices: State Of the Artmentioning

confidence: 99%

“…Design can deal with this to a certain extent. For example, the electronic parts of the suction device of Nava et al [13] are not sterilized but are integrated in the system and the authors mention that they are never in direct contact with the patient.…”

Section: In Vivo Devices: State Of the Artmentioning

confidence: 99%

LASTIC: A Light Aspiration Device for in vivo Soft TIssue Characterization

Schiavone

Promayon

Payan

2010

Biomedical Simulation

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Abstract. This paper introduces a new Light Aspiration device for in vivo Soft TIssue Characterization (LASTIC). This device is designed to be used during surgery, and can undergo sterilization. It provides interactive-time estimation of the elastic parameters. LASTIC is a 3cm x 3cm metallic cylinder divided in two compartments. The lower compartment is a cylindrical chamber made airtight by a glass window in which a negative pressure can be applied. Put in contact with soft tissues, it can aspirate the tissues into the chamber through a circular aperture in its bottom side. The upper compartment is clinched onto the lower part. A miniature digital camera is fixed inside the upper chamber, focusing on the aspirated soft tissue. LASTIC is operated by applying a range of negative pressures in the lower compartment while measuring the resulting aspirated tissue deformations with the digital camera. These measurements are used to estimate the tissue elasticity parameters by inverting a Finite Element model of the suction experiment. In order to use LAS-TIC during surgical interventions, a library-based optimization process is used to provide an interactive time inversion.

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“…For example, the contrast in elastic stiffness between normal and abnormal liver, breast and prostate tissue has been studied. 4,5 Krouskop et al [6][7][8][9] characterized the elastic behavior of breast and prostatic tissue using an indentation technique under varying compression strains. Their results confirmed that malignant changes of the breast and prostate correlated with decreases in tissue elasticity.…”

Section: Introductionmentioning

confidence: 99%

“…10,11 Several prostate simulators currently exist including the G300 life-size prostate model set (Anatomical Chart Company, Skokie, IL, USA) and the Life/form prostate examination simulator (Nasco, Fort Atkinson, WI, USA). However, these simulators present a very limited number of scenarios (3)(4)(5)(6), either lack or misrepresent tactile cues, offer little feedback to learners and do not offer a range of 'normal' consistencies based on scientific measurement.…”

Section: Introductionmentioning

confidence: 99%

Construct validity in a high-fidelity prostate exam simulator

Kowalik

Gerling

Lee

et al. 2011

Prostate Cancer Prostatic Dis

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BACKGROUND: All health care practitioners should be facile in the digital rectal exam (DRE) as it provides prostate, rectal and neurological information. The purpose of this study was first to justify our hypothesis that tissue elasticity is indicative of carcinomatous changes. Second, we employed urological surgeons to evaluate our prostate simulator in three ways: (1) authenticate that the elasticity of the simulated prostates accurately represents the range of normal prostate stiffness, (2) determine the range of nodule size reasonably palpable by DRE and (3) discern what degree of elasticity difference within the same prostate suggests malignancy. METHODS:Institutional Review Board-approved materials characterization, human-subjects experiments, histopathology and chart abstraction of clinical history were performed. Material characterization of 21 ex-vivo prostatectomy specimens was evaluated using a custom-built, portable spherical indentation device while a novel prostate simulator was employed to measure human-subject perception of prostatic state. RESULTS:From the materials characterization, the measurements of the 21 gross prostates and 40 cross-sections yielded 306 data points. Within the same prostate, cancer was always stiffer. Of the seven cases with an abnormal DRE, the DRE accurately identified adenocarcinoma in 85%. From the human-subjects experiments, the simulated prostates evaluated by urologists ranged in stiffness from 8.9 to 91 kPa, mimicking the range found on ex vivo analysis of 4.6-236.7 kPa. The urological surgeons determined the upper limit of stiffness palpated as realistic for a healthy prostate was 59.63 kPa while the lower limit of stiffness was 27.1 kPa. Nodule size less than 7.5 mm was felt to be too small to reasonably palpate. CONCLUSIONS:We found it is not the absolute elasticity of the nodule, but rather the relationship of the nodule with the background prostate elasticity that constitutes the critical tactile feedback. Prostate simulator training may lead to greater familiarity with pertinent diagnostic cues and diagnosis of prostate cancer.

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In vivo mechanical characterization of human liver

Cited by 193 publications

References 28 publications

Dynamic Material Properties of Human and Animal Livers

Dynamic Material Properties of Human and Animal Livers

LASTIC: A Light Aspiration Device for in vivo Soft TIssue Characterization

Construct validity in a high-fidelity prostate exam simulator

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