Automatic analysis of collagen fiber orientation in the outermost layer of human arteries

Elbischger, Pierre; Bischof, Horst; Regitnig, Peter; Holzapfel, Gerhard

doi:10.1007/bf02683993

Cited by 15 publications

(17 citation statements)

References 32 publications

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“…In particular, the assumption made in this study regarding the structural fabric in the three layers needs to be analysed in more detail. Despite the seminal work (Canham et al, 1989), in which the threedimensional structural fabric of the different layers in human coronary arteries are analysed by means of polarizing light microscopy, there is some recent work that makes progress in quantifying the patterns of orientation by using microscopy (Finlay et al, 1995), Section 2 in Holzapfel et al (2002), small-angle light scattering (Billiar and Sacks, 1997), and suitable image processing tools (Elbischger et al, 2004). Apart from the shortcomings already discussed, there are additional problems with uniaxial extension tests.…”

Section: Discussionmentioning

confidence: 99%

Determination of material models for arterial walls from uniaxial extension tests and histological structure

Holzapfel

2006

Journal of Theoretical Biology

273

219

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An approach is proposed that allows the determination of material models from uniaxial tests and histostructural data including fiber orientation of the tissue. A combination of neo-Hookean and Fung-type strain-energy functions is utilized, and inequality constraints imposed on the constitutive parameters are derived providing strict local convexity and preferred fiber orientations. It is shown how the Fung-type model gets a pseudo-structural aspect inherent in the phenomenological model; a correlation between the fiber structure and the parameters of the Fung-type model is explicitly provided. In order to apply the proposed approach, quasi-static uniaxial extension tests of preconditioned prepared strips from the intima, media and adventitia of a human aorta with non-atherosclerotic intimal thickening are acquired in axial and circumferential directions; structural information from histological analyses for each aortic tissue are documented. Data reveal a remarkable thickness, load-bearing capacity and stiffness of the intimal samples in comparison with the media and adventitia. Constitutive parameters for each aortic tissue layer are determined by solving the constrained problem using a penalty function method; a new approach for the estimation of appropriate start values is proposed. Finally, the predictivity and efficacy of the material models is shown by comparing model data with data from the uniaxial extension tests and histological image analyses.

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Section: Discussionmentioning

confidence: 99%

Determination of material models for arterial walls from uniaxial extension tests and histological structure

Holzapfel

2006

Journal of Theoretical Biology

273

219

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“…The separation between these two variations is not straightforward and requires segmentation of images into areas with a common mean orientation. Elbischger et al studied local extraction of crimp parameters of collagen fibers from a single image (Elbischger et al 2004). The images were taken using light microscopy from sliced fixed paraffin-embedded human iliac arteries.…”

Section: Analysis Of Local Angle Distributionmentioning

confidence: 99%

Experimental investigation of collagen waviness and orientation in the arterial adventitia using confocal laser scanning microscopy

Rezakhaniha

Agianniotis

Schrauwen

et al. 2011

Biomech Model Mechanobiol

905

786

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Mechanical properties of the adventitia are largely determined by the organization of collagen fibers. Measurements on the waviness and orientation of collagen, particularly at the zero-stress state, are necessary to relate the structural organization of collagen to the mechanical response of the adventitia. Using the fluorescence collagen marker CNA38-OG488 and confocal laser scanning microscopy, we imaged collagen fibers in the adventitia of rabbit common carotid arteries ex vivo. The arteries were cut open along their longitudinal axes to get the zero-stress state. We used semi-manual and automatic techniques to measure parameters related to the waviness and orientation of fibers. Our results showed that the straightness parameter (defined as the ratio between the distances of endpoints of a fiber to its length) was distributed with a beta distribution (mean value 0.72, variance 0.028) and did not depend on the mean angle orientation of fibers. Local angular density distributions revealed four axially symmetric families of fibers with mean directions of 0 • , 90 • , 43 • and −43 • , with respect to the axial direction of the artery, and corresponding circular standard deviations of 40 • , 47 • , 37 • and 37 • . The distribution of local orientations was shifted to the circumferential direction when measured in arteries at the zero-load state (intact), as compared to arteries at the zero-stress state (cutopen). Information on collagen fiber waviness and orientation, such as obtained in this study, could be used to develop structural models of the adventitia, providing better means for analyzing and understanding the mechanical properties of vascular wall.

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“…Secondly, the use of a continuum fibre-reinforced hyperelastic model (Holzapfel et al, 2000;Limbert, 2011;Limbert and Taylor, 2002;Weiss et al, 1996) entails the definition of a unit vector field corresponding to the local orientation of collagen fibres. It is possible to extract this information from histological sections by statistical analysis of pixels (Elbischger et al, 2004) but, in the absence of accurate structural information, any deviation from the real collagen bundle orientations might lead to very different results.…”

Section: Mechanical Properties Of Skinmentioning

confidence: 99%

A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin

Leyva-Mendivil

Page

Bressloff

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

109

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A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.www.elsevier.com/locate/jmbbm 1 A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin. AbstractThe study of skin biophysics has largely been driven by consumer goods, biomedical and cosmetic industries which aim to design products that efficiently interact with the skin and/or modify its biophysical properties for health or cosmetic benefits. The skin is a hierarchical biological structure featuring several layers with their own distinct geometry and mechanical properties. Up to now, no computational models of the skin have simultaneously accounted for these geometrical and material characteristics to study their complex biomechanical interactions under particular macroscopic deformation modes.The goal of this study was, therefore, to develop a robust methodology combining histological sections of human skin, image-processing and finite element techniques to address fundamental questions about skin mechanics and, more particularly, about how macroscopic strains are transmitted and modulated through the epidermis and dermis. The work hypothesis was that, as skin deforms under macroscopic loads, the stratum corneum does not experience significant strains but rather folds/unfolds during skin extension/compression.A sample of fresh human mid-back skin was processed for wax histology. Sections were stained and photographed by optical microscopy. The multiple images were stitched together to produce a larger region of interest and segmented to extract the geometry of the stratum corneum, viable epidermis and dermis. From the segmented structures a 2D finite element mesh of the skin composite model was created and geometrically non-linear plane-strain finite element analyses were conducted to study the sensitivity of the model to variations in mechanical properties.The hybrid experimental-computational methodology has offered valuable insights into the simulated mechanics of the skin, and that of the stratum corneum in particular, by providing qualitative and quantitative information on strain magnitude and distribution. Through a complex non-linear interplay, the geometry and mechanical characteristics of the skin layers (and their relative balance), play a critical role in conditioning the skin mechanical response to macroscopic in-plane compression and extension. Topographical features of the skin surface such as furrows were shown to act as an efficient means to deflec...

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Automatic analysis of collagen fiber orientation in the outermost layer of human arteries

Cited by 15 publications

References 32 publications

Determination of material models for arterial walls from uniaxial extension tests and histological structure

Determination of material models for arterial walls from uniaxial extension tests and histological structure

Experimental investigation of collagen waviness and orientation in the arterial adventitia using confocal laser scanning microscopy

A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin

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