Closed-Cell Stent-Assisted Coiling of Intracranial Aneurysms: Evaluation of Changes in Vascular Geometry Using Digital Subtraction Angiography

Background Stent-assisted coil embolization (SACE) plays an important role in the treatment of intracranial aneurysms. The purpose of this study was to investigate geometrical changes caused by closed-cell design stents in bifurcation and sidewall aneurysms. Methods 31 patients with 34 aneurysms underwent SACE with closed-cell design stents. Inflow angle alpha, determined by aneurysm neck and afferent vessel, and angle between afferent and efferent vessel close to (delta(1)), respectively, more remote from the aneurysm neck (delta(2)) were graphically determined in 2D angiography projections. Results Stent assisted coiling resulted in a significant increase of all three angles from a mean value (+/- SEM) of alpha = 119 degrees (+/- 6.5 degrees) pretreatment to 130 degrees (+/- 6.6 degrees) posttreatment (P <= .001), delta(1) = 129 degrees (+/- 6.4 degrees) to 139 degrees (+/- 6.1 degrees), (P <= .001) and delta(2) = 115 degrees (+/- 8.4 degrees) to 126 degrees (+/- 7.5 degrees), (P <= .01). Angular change of d1 in AcomA aneurysms was significant greater compared to sidewall aneurysms (26 degrees +/- 4.9 degrees versus 8 degrees +/- 2.3 degrees, P <= .05). The initial angle of delta(1) and delta(2) revealed a significantly inverse relationship to the angle increase (delta(1): r = -0.41, P <= .05 and delta(2): r = -0.47, P <= .01). Moreover, angle delta(1) was significantly higher in unruptured compared to ruptured aneurysms (135 degrees +/- 7.1 degrees versus 103 degrees +/- 10.8 degrees, P <= .05). Conclusion Stent deployment modulates the geometry of the aneurysm-vessel complex, which may lead to favorable hemodynamic changes more similar to unruptured than to ruptured aneurysms. Our findings also suggest that the more acute-angled aneurysm-vessel anatomy, the larger the angular change. Further studies are needed to investigate whether these changes improve the clinical outcome.