Comparison of in vivo vs. ex situ obtained material properties of sheep common carotid artery. (May 2018)

• Record Type: Journal Article
• Authors: Smoljkić, Marija; Verbrugghe, Peter; Larsson, Matilda; Widman, Erik; Fehervary, Heleen; D'hooge, Jan; Vander Sloten, Jos; Famaey, Nele
• Is Part Of: Medical engineering & physics. Volume 55(2018)
• Page Start: 16
• Page End: 24
• Publication Date: 2018-05
• Subjects: Common carotid artery -- Material properties -- Constitutive modelling -- Parameter estimation; Biomedical engineering -- Periodicals; Biomedical Engineering -- Periodicals; Physics -- Periodicals; Génie biomédical -- Périodiques; Biomedical engineering; Electronic journals; Periodicals; 610.28
• DOI: 10.1016/j.medengphy.2018.03.006
• Languages: English
• ISSNs: 1350-4533

Abstract

Highlights: Planar biaxial and in vivo material property estimation of sheep common carotid arteries are reported on the same tissue. Anisotropic and isotropic nonlinear material fittings were compared for both methods. The in vivo method and the planar biaxial method yield significantly different results. The in vivo method has the advantage of capturing the behaviour in the most relevant conditions. The planar biaxial method is better suited to capture the anisotropy of the tissue. Abstract: Patient-specific biomechanical modelling can improve preoperative surgical planning. This requires patient-specific geometry as well as patient-specific material properties as input. The latter are, however, still quite challenging to estimate in vivo . This study focuses on the estimation of the mechanical properties of the arterial wall. Firstly, in vivo pressure, diameter and thickness of the arterial wall were acquired for sheep common carotid arteries. Next, the animals were sacrificed and the tissue was stored for mechanical testing. Planar biaxial tests were performed to obtain experimental stress-stretch curves. Finally, parameters for the hyperelastic Mooney–Rivlin and Gasser–Ogden–Holzapfel (GOH) material model were estimated based on the in vivo obtained pressure-diameter data as well as on the ex situ experimental stress-stretch curves. Both material models were able to capture the in vivo behaviour of the tissue. However, in the ex situ case only the GOH model provided satisfactory results. When comparing different fitting approaches, in vivo vs. ex situ, each of them showed its own advantages and disadvantages. The in vivo approach estimates the properties of the tissue in its physiological state while the ex situ approach allows to apply different loadings to properly capture the anisotropy of the tissue. Both of them could be further enhanced by improving the estimation of the stress-free state, i.e. by adding residual circumferential stresses in vivo and by accounting for the flattening effect of the tested samples ex vivo . Competing interests: none declared Word count: 4716