KEYWORDS: Angiography, Neck, Scanning electron microscopy, Arteries, Polyurethane, In vivo imaging, Animal model studies, Electron microscopy, Hemodynamics, Domes
Image-guided endovascular intervention (EIGI), using new flow modifying endovascular devices for intracranial
aneurysm treatment is an active area of stroke research. The new polyurethane-asymmetric vascular stent (P-AVS), a
vascular stent partially covered with a polyurethane-based patch, is used to cover the aneurysm neck, thus occluding
flow into the aneurysm. This study involves angiographic imaging of partially covered aneurysm orifices. This
particular situation could occur when the vascular geometry does not allow full aneurysm coverage. Four standard in-vivo
rabbit-model aneurysms were investigated; two had stent patches placed over the distal region of the aneurysm
orifice while the other two had stent patches placed over the proximal region of the aneurysm orifice. Angiographic
analysis was used to evaluate aneurysm blood flow before and immediately after stenting and at four-week follow-up.
The treatment results were also evaluated using histology on the aneurysm dome and electron microscopy on the
aneurysm neck. Post-stenting angiographic flow analysis revealed aneurysmal flow reduction in all cases with faster
flow in the distally-covered case and very slow flow and prolonged pooling for proximal-coverage. At follow-up,
proximally-covered aneurysms showed full dome occlusion. The electron microscopy showed a remnant neck in both
distally-placed stent cases but complete coverage in the proximally-placed stent cases. Thus, direct flow (impingement
jet) removal from the aneurysm dome, as indicated by angiograms in the proximally-covered case, was sufficient to
cause full aneurysm healing in four weeks; however, aneurysm healing was not complete for the distally-covered case.
These results support further investigations into the treatment of aneurysms by flow-modification using partial
aneurysm-orifice coverage.
Effective minimally invasive treatment of cerebral bifurcation aneurysms is challenging due to the complex and
remote vessel morphology. An evaluation of endovascular treatment in a phantom involving image-guided deployment
of new asymmetric stents consisting of polyurethane patches placed to modify blood flow into the aneurysm is reported.
The 3D lumen-geometry of a patient-specific basilar-artery bifurcation aneurysm was derived from a segmented
computed-tomography dataset. This was used in a stereolithographic rapid-prototyping process to generate a mold
which was then used to create any number of exact wax models. These models in turn were used in a lost-wax technique
to create transparent elastomer patient-specific aneurysm phantoms (PSAP) for evaluating the effectiveness of
asymmetric-stent deployment for flow modification. Flow was studied by recording real-time digitized video images of
optical dye in the PSAP and its feeding vessel. For two asymmetric stent placements: through the basilar into the right-posterior
communicating artery (RPCA) and through the basilar into the left-posterior communicating artery (LPCA),
the greatest deviation of flow streamlines away from the aneurysm occurred for the RPCA stent deployment. Flow was
also substantially affected by variations of inflow angle into the basilar artery, resulting in alternations in washout times
as derived from time-density curves. Evaluation of flow in the PSAPs with real-time optical imaging can be used to
determine new EIGI effectiveness and to validate computational-fluid-dynamic calculations for EIGI-treatment
planning.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.