[Coil Embolization Strategy Based on Aneurysm Morphology: Roles of Framing, Filling, and Finishing Coils]

Coil embolization remains an important technique for treating cerebral aneurysms, even with the development of new devices such as flow diverters and flow disruption systems. To achieve stable occlusion, it is important to use coils in three steps: framing, filling, and finishing. The framing coil creates the initial support inside the aneurysm and helps prevent rupture during the procedure. Filling coils are then placed to pack the aneurysm densely and evenly. Finishing coils are used at the end to close the small space near the neck and reduce the risk of recurrence. As aneurysms vary in shape-simple, irregular, or very small-the optimal coil strategy differs from case to case. Selecting the appropriate type of coil for the aneurysm shape and catheter position is essential for both safety and effectiveness. This review explains practical considerations for each step and shows how aneurysm morphology can guide coil selection to improve treatment outcomes.