The Volume Embolization Ratio (VER) for coiling was calculated using the following algebraic equation: VER = (volume of the embolized coil) / (volume of the aneurysm) * 100%
The aneurysm volume was calculated before embolization as follows assuming that the aneurysm was ellipsoid: aneurysm volume (AV) = (4π/3) * (A/2) * (B/2) * (C/2), where A, B and C are the aneurysm length, width and height, respectively 1).