OBJECTIVES: Intra-aneurysmal coil embolization has been established as a common method for the intravascular treatment of cerebral aneurysms, but few studies have evaluated its long-term results. Because there is no sufficient objective landmark of complete embolization, determination of its application depends on a surgeon's experience. METHODS: A glass cerebral aneurysm model was produced, and the changes in intra-aneurysmal hemodynamics were examined. Nylon thread with a diameter of 0.33 mm, resembling the coils clinically used for embolization, was used to fill in the model. After perfusion of glycerin solution to represent human blood, the half life of a dye injected into the aneurysm was optically measured, and the relationship between the half life and the volume embolization rate (VER) of nylon thread in the aneurysm was examined. RESULTS: The maximal VER obtained by filling nylon thread in the aneurysm was 41.7+/- 2.9%. The half life of the dye increased with the VER and was significantly increased at VER>30%. DISCUSSION: The half life of the dye in the aneurysm reflected stagnation of intra-aneurysmal hemodynamics, suggesting that the prolongation of the half life enhances thrombus formation. The results of this study suggested that VER>30% is sufficient for effective coil embolization.
OBJECTIVES:Intra-aneurysmal coil embolization has been established as a common method for the intravascular treatment of cerebral aneurysms, but few studies have evaluated its long-term results. Because there is no sufficient objective landmark of complete embolization, determination of its application depends on a surgeon's experience. METHODS: A glass cerebral aneurysm model was produced, and the changes in intra-aneurysmal hemodynamics were examined. Nylon thread with a diameter of 0.33 mm, resembling the coils clinically used for embolization, was used to fill in the model. After perfusion of glycerin solution to represent human blood, the half life of a dye injected into the aneurysm was optically measured, and the relationship between the half life and the volume embolization rate (VER) of nylon thread in the aneurysm was examined. RESULTS: The maximal VER obtained by filling nylon thread in the aneurysm was 41.7+/- 2.9%. The half life of the dye increased with the VER and was significantly increased at VER>30%. DISCUSSION: The half life of the dye in the aneurysm reflected stagnation of intra-aneurysmal hemodynamics, suggesting that the prolongation of the half life enhances thrombus formation. The results of this study suggested that VER>30% is sufficient for effective coil embolization.