title: A Framework for Local Mechanical Characterization of Atherosclerotic Plaques: Combination of Ultrasound Displacement Imaging and Inverse Finite Element Analysis.
abstract: Biomechanical models have the potential to predict plaque rupture. For reliable models, correct material properties of plaque components are a prerequisite. This study presents a new technique, where high resolution ultrasound displacement imaging and inverse finite element (FE) modeling is combined, to estimate material properties of plaque components. Iliac arteries with plaques were excised from 6 atherosclerotic pigs and subjected to an inflation test with pressures ranging from 10 to 120 mmHg. The arteries were imaged with high frequency 40 MHz ultrasound. Deformation maps of the plaques were reconstructed by cross correlation of the ultrasound radiofrequency data. Subsequently, the arteries were perfusion fixed for histology and structural components were identified. The histological data were registered to the ultrasound data to construct FE model of the plaques. Material properties of the arterial wall and the intima of the atherosclerotic plaques were estimated using a grid search method. The computed displacement fields showed good agreement with the measured displacement fields, implying that the FE models were able to capture local inhomogeneities within the plaque. On average, nonlinear stiffening of both the wall and the intima was observed, and the wall of the atheroslcerotic porcine iliac arteries was markedly stiffer than the intima (877 ± 459 vs. 100 ± 68 kPa at 100 mmHg). The large spread in the data further illustrates the wide variation of the material properties. We demonstrated the feasibility of a mixed experimental-numerical framework to determine the material properties of arterial wall and intima of atherosclerotic plaques from intact arteries, and concluded that, due to the observed variation, plaque specific properties are required for accurate stress simulations.
authors.affiliation: Biomechanics Lab, Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.|Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, USA.
authors.forename: Ali C
authors.initials: AC
authors.lastname: Akyildiz
authors.affiliation: Medical UltraSound Imaging Center (MUSIC), Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Hendrik H G
authors.initials: HH
authors.lastname: Hansen
authors.affiliation: Biomechanics Lab, Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: Harm A
authors.initials: HA
authors.lastname: Nieuwstadt
authors.affiliation: Biomechanics Lab, Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: Lambert
authors.initials: L
authors.lastname: Speelman
authors.affiliation: Medical UltraSound Imaging Center (MUSIC), Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Chris L
authors.initials: CL
authors.lastname: De Korte
authors.affiliation: Biomechanics Lab, Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.|Department of Applied Sciences, Delft University of Technology, Delft, The Netherlands.
authors.forename: Antonius F W
authors.initials: AF
authors.lastname: van der Steen
authors.affiliation: Biomechanics Lab, Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands. f.gijsen@erasmusmc.nl.
authors.forename: Frank J H
authors.initials: FJ
authors.lastname: Gijsen
mesh_terms: D000818:Animals; D020342:Finite Element Analysis; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D013552:Swine; D014463:Ultrasonography
keywords: Atherosclerotic plaque; Inverse method; Material properties; Ultrasound