Purpose : To evaluate the usefulness of CT angiography and to compare SSD(Shaded Surface Display) andMIP(Maximum Intensity Projection) in the diagnosis and preoperative evaluation of the cerebral aneurysms.Materials and Methods : Twenty-six aneurysms in 20 patients were diagnosed on conventional angiography and surgerywas performed. For preoperative evaluation, all patients underwent CT angiography, with spiral CT for preoperativeevaluation. Using SSD and MIP techniques, the results were proccessed and compared; three radiologistsretrospectively analysed detectability, size, neck visualization, delineation of shape, direction, therelationship with surrounding vessels-including the feeding artery of the aneurysm-and intraluminal thrombicontaining calcification. Results : Twenty five of 26 aneurysms (96.2%) were detected by CT angiography, while MIPand SSD depicted 25 (96.2%) and 24 (92.3%), respectively. The largest diameter of the aneurysms was 11-15mm infour cases, 6-10mm in ten, and 3-5mm in 12 (mean 7.38mm, SD=3.34). With regard to detectability, MIP led to onefalse negative result, and SSD to two false negative and one false-positive results. Aneurysm neck assessment byMIP was clear in 96.0% of cases (24/25), and by SSD in 83.3% (20/24). For the depiction of directions and feedingvessels of the aneurysms, and intraluminal thrombi containing calcification, MIP was superior to SSD, while fordepicting shape and the relationship with surrounding structures, SSD was superior to MIP. Conclusion : For theassessment of cerebral aneurysms, MIP is somewhat superior to SSD. The characteristics of aneurysms and theirrelationship with surrounding structures can, however, be better evaluated by combining the two techniques.