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
