Aneurysm volume/virtual column volume (AV/CV) ratio, calculated from measurements derived from reconstructed images based on rotational three-dimensional digital subtraction angiography (3D-DSA), was investigated as a predictor of the success of intraaneurysmal embolization in 20 unruptured wide-necked internal carotid artery aneurysms treated by Guglielmi detachable coils. AV and neck area were automatically calculated with a workstation. CV was defined as the product of height and neck area of the aneurysm. The percentage of aneurysm occlusion at the end of the procedure was evaluated by volume embolization ratio (VER). Successful intraaneurysmal embolization (VER >or= 20%) was achieved in 10 of 11 aneurysms with AV/CV ratios of more than 1.0, whereas failed embolization (VER=0%) was observed in 3 of 4 aneurysms with AV/CV ratios of less than 0.8. The AV/CV ratio is a possible predictor of embolization success, which can be easily calculated using 3D-DSA.