In four difficult aneurysms cases, preoperative views of surgical approach were obtained by three-dimensional and multiplanar reconstruction imaging methods using helical CT scanner. Simulation of various surgical approach views are also possible and an appropriate surgical approach is selected by comparing various surgical views. With this imaging technique, elimination of skull base bone, namely, simulation of bone drilling including the site and extent of bone resection is freely available. The diameter of the orifice of aneurysms and calcified portion of the wall are also visualized. One of the limitations is that small vessels less than 1 mm in diameter are not visualized.
