2 research outputs found
Comparison of two stents in modifying cerebral aneurysm hemodynamics
There is a general lack of quantitative understanding about how specific design features of
endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial
aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar
stent™ and Wallstent®) in aneurysm models of varying vessel curvature as well as in a patientspecific model using Computational Fluid Dynamics. We investigated how these stents modify
hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such
changes are related to the specific designs. We found that the flow damping effect of stents and
resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut
design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at
higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone
treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can
be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a
methodology to cost-effectively compare different stent designs before running a full 3D simulation
Morphology parameters for intracranial aneurysm rupture risk assessment
OBJECTIVE—The aim of this study is to identify image-based morphological parameters that
correlate with human intracranial aneurysm (IA) rupture.
METHODS—For 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured),
three-dimensional geometries were evaluated for a range of morphological parameters. In addition
to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity
index, and undulation index), we defined three novel parameters incorporating the parent vessel
geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and
explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed
independent Student's t test for significance; significant parameters (P < 0.05) were further examined
by multivariate logistic regression analysis. Additionally, receiver operating characteristic analyses
were performed on each parameter.
RESULTS—Statistically significant differences were found between mean values in ruptured and
unruptured groups for size ratio, undulation index, nonsphericity index, ellipticity index, aneurysm
angle, and aspect ratio. Logistic regression analysis further revealed that size ratio (odds ratio, 1.41;
95% confidence interval, 1.03−1.92) and undulation index (odds ratio, 1.51; 95% confidence interval,
1.08−2.11) had the strongest independent correlation with ruptured IA. From the receiver operating
characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of
0.83 and 0.85, respectively.
CONCLUSION—Size ratio and aneurysm angle are promising new morphological metrics for IA
rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the
gap between morphological studies and more qualitative location-based studies