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 α, determined by aneurysm neck and afferent vessel, and angle between afferent and efferent vessel close to (δ(1)), respectively, more remote from the aneurysm neck (δ(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 α = 119° (±6.5°) pretreatment to 130° (±6.6°) posttreatment (P ≤ .001), δ(1) = 129° (±6.4°) to 139° (±6.1°), (P ≤ .001) and δ(2) = 115° (±8.4°) to 126° (±7.5°), (P ≤ .01). Angular change of δ(1) in AcomA aneurysms was significant greater compared to sidewall aneurysms (26°±4.9° versus 8°± 2.3°, P ≤ .05). The initial angle of δ(1) and δ(2) revealed a significantly inverse relationship to the angle increase (δ(1): r = -0.41, P ≤ .05 and δ(2): r = -0.47, P ≤ .01). Moreover, angle δ(1) was significantly higher in unruptured compared to ruptured aneurysms (135°±7.1° versus 103°±10.8°, 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.