title: Influence of wall thickness and diameter on arterial shear wave elastography: a phantom and finite element study.
abstract: Quantitative, non-invasive and local measurements of arterial mechanical properties could be highly beneficial for early diagnosis of cardiovascular disease and follow up of treatment. Arterial shear wave elastography (SWE) and wave velocity dispersion analysis have previously been applied to measure arterial stiffness. Arterial wall thickness (h) and inner diameter (D) vary with age and pathology and may influence the shear wave propagation. Nevertheless, the effect of arterial geometry in SWE has not yet been systematically investigated. In this study the influence of geometry on the estimated mechanical properties of plates (h  =  0.5-3 mm) and hollow cylinders (h  =  1, 2 and 3 mm, D  =  6 mm) was assessed by experiments in phantoms and by finite element method simulations. In addition, simulations in hollow cylinders with wall thickness difficult to achieve in phantoms were performed (h  =  0.5-1.3 mm, D  =  5-8 mm). The phase velocity curves obtained from experiments and simulations were compared in the frequency range 200-1000 Hz and showed good agreement (R2=  0.80  ±  0.07 for plates and R2=  0.82  ±  0.04 for hollow cylinders). Wall thickness had a larger effect than diameter on the dispersion curves, which did not have major effects above 400 Hz. An underestimation of 0.1-0.2 mm in wall thickness introduces an error 4-9 kPa in hollow cylinders with shear modulus of 21-26 kPa. Therefore, wall thickness should correctly be measured in arterial SWE applications for accurate mechanical properties estimation.
authors.affiliation: Department of Medical Engineering, School of Technology and Health, KTH Royal Institute of Technology, Hälsovägen 11C, SE-141 57 Stockholm, Sweden. Department of Clinical Physiology, Karolinska Institutet, SE-17176 Stockholm, Sweden.
authors.forename: Elira
authors.initials: E
authors.lastname: Maksuti
authors.forename: Fabiano
authors.initials: F
authors.lastname: Bini
authors.forename: Stefano
authors.initials: S
authors.lastname: Fiorentini
authors.forename: Giulia
authors.initials: G
authors.lastname: Blasi
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Urban
authors.forename: Franco
authors.initials: F
authors.lastname: Marinozzi
authors.forename: Matilda
authors.initials: M
authors.lastname: Larsson
mesh_terms: D001158:Arteries / Q000000981:diagnostic imaging* / Q000473:pathology; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000295:instrumentation* / Q000379:methods; D020342:Finite Element Analysis; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D019047:Phantoms, Imaging; D033081:Shear Strength; D059289:Vascular Stiffness