title: Carotid plaque elasticity estimation using ultrasound elastography, MRI, and inverse FEA - A numerical feasibility study.
abstract: The material properties of atherosclerotic plaques govern the biomechanical environment, which is associated with rupture-risk. We investigated the feasibility of noninvasively estimating carotid plaque component material properties through simulating ultrasound (US) elastography and in vivo magnetic resonance imaging (MRI), and solving the inverse problem with finite element analysis. 2D plaque models were derived from endarterectomy specimens of nine patients. Nonlinear neo-Hookean models (tissue elasticity C1) were assigned to fibrous intima, wall (i.e., media/adventitia), and lipid-rich necrotic core. Finite element analysis was used to simulate clinical cross-sectional US strain imaging. Computer-simulated, single-slice in vivo MR images were segmented by two MR readers. We investigated multiple scenarios for plaque model elasticity, and consistently found clear separations between estimated tissue elasticity values. The intima C1 (160 kPa scenario) was estimated as 125.8 ± 19.4 kPa (reader 1) and 128.9 ± 24.8 kPa (reader 2). The lipid-rich necrotic core C1 (5 kPa) was estimated as 5.6 ± 2.0 kPa (reader 1) and 8.5 ± 4.5 kPa (reader 2). A scenario with a stiffer wall yielded similar results, while realistic US strain noise and rotating the models had little influence, thus demonstrating robustness of the procedure. The promising findings of this computer-simulation study stimulate applying the proposed methodology in a clinical setting.
authors.affiliation: Department of Biomedical Engineering, Erasmus MC, Rotterdam, The Netherlands. Electronic address: h.nieuwstadt@erasmusmc.nl.
authors.forename: H A
authors.initials: HA
authors.lastname: Nieuwstadt
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Fekkes
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: H H G
authors.initials: HH
authors.lastname: Hansen
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: C L
authors.initials: CL
authors.lastname: de Korte
authors.affiliation: Department of Radiology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: van der Lugt
authors.affiliation: Department of Biomedical Engineering, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: J J
authors.initials: JJ
authors.lastname: Wentzel
authors.affiliation: Department of Biomedical Engineering, Erasmus MC, Rotterdam, The Netherlands; Department of Imaging Science and Technology, Delft University of Technology, Delft, The Netherlands.
authors.forename: A F W
authors.initials: AF
authors.lastname: van der Steen
authors.affiliation: Department of Biomedical Engineering, Erasmus MC, Rotterdam, The Netherlands. Electronic address: f.gijsen@erasmusmc.nl.
authors.forename: F J H
authors.initials: FJ
authors.lastname: Gijsen
mesh_terms: D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging* / Q000473:pathology*; D003198:Computer Simulation; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005240:Feasibility Studies; D020342:Finite Element Analysis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000473:pathology*
keywords: Biomechanical modeling; Carotid atherosclerosis; Elasticity estimation; Finite element analysis; Inverse problem; Magnetic resonance imaging; Ultrasound elastography