Abstract
Introduction
High-porosity (HP) and flow-diverting (FD) stents are increasingly used to treat intracranial aneurysms. In vivo device deformations and their impact on the porosity of the segment of device lying over the aneurysm neck remain inadequately characterized.
Methods
Porosities of different braided FDs were studied in straight and 90° curved glass tubes. In vivo, 11 experimental lateral wall aneurysms were treated with FD (n = 7) or HP (n = 4) stents. At 3 months, the segment of FDs and HP stents over the aneurysm neck was analyzed, paying attention to changes in device diameter, metallic porosity, and neointimal closure of pores over the aneurysm or branch ostia. Device deformations were reproduced with benchtop experiments.
Results
In 90° curved tubes, FD porosity was higher (P = 0.025) and pore density was lower (P = 0.01) on convex compared to concave surfaces, but variations remained within 5–10 %. After in vivo deployment, a spindle-shaped deformation of FDs occurred, with focal expansion at the level of the aneurysm neck (P = 0.004). This deformation translated into an accordion-like distribution of stent struts across the aneurysm neck, where porosity was not uniform. The midsection of the aneurysm ostium had more metal coverage than adjacent ostial areas (P = 0.002). Mean porosity over the aneurysm neck was 78 ± 9.4 and 32.6 ± 12.1 % for HP and FD stents, respectively (P = 0.008), decreasing to 13.0 ± 10.1 and 1.4 ± 0.6 % (P = 0.022) following neointimal coverage, respectively. Spindle-shaped deformations and accordion effects were reproduced with benchtop manipulations; fluctuations in porosity and diameter changes correlated closely (R = 0.81; P = 0.005).
Conclusion
Alterations in porosity may occur following in vivo implantation.
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Acknowledgments
This work was partially supported by the “Fondation de l’Association des Radiologistes du Québec” (FARQ) in collaboration with “Fonds de la Recherche en Santé du Québec” (FRSQ) grant (to Dr. Jean Raymond). This work was also supported by an Imaging Research Bursary Fellowship from “Société Française de Radiologie” to Dr. Fabrice Bing and a pilot project grant from the “Society of Interventional Radiology” (SIR) to Dr. Tim Darsaut. Stents and FDs were gifts from Microvention Inc.
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Bing, F., Darsaut, T.E., Salazkin, I. et al. Stents and flow diverters in the treatment of aneurysms: device deformation in vivo may alter porosity and impact efficacy. Neuroradiology 55, 85–92 (2013). https://doi.org/10.1007/s00234-012-1082-0
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DOI: https://doi.org/10.1007/s00234-012-1082-0