Abstract: Objective To assess the diagnostic value of three dimensional multi-slice spiral computed tomography angiography(3D-MSCTA)in detecting intracranial aneurysms.Methods The imaging data of 31 patients with intracranial aneurysms were retrospectively analyzed, 13 patients were performed with DSA, 4 patients were conformed by operation.Reconstruction types of MSCTA included volume rendering(VR), maximum intensity projection(MIP), multi-plane reformation(MPR)and curved plane reconstruction(CPR).Results In the 31 cases, 38 aneurysms were detected by MSCTA.Three cases had two aneurysms, two cases had three aneurysms.The locations of the aneurysm were middle cerebral artery(n=9), anterior cerebral artery(n=7), posterior cerebral artery(n=2), posterior communicating artery(n=3), carotid(n=12), basilar artery(n=3), corpus peripheral artery(n=1), superior cerebellar artery(n=1).The minimum diameter was 1.0mm×1.3mm, The maximum diameter was 59mm×73mm.MSCTA can precisely display the size, configuration and direction of intracranial aneurysms, and their anatomic connection with surrounding vessels and bones using 3D post-processing methods.Compared with DSA, 16 aneurysms were detected by MSCTA and 13 by DSA.One aneurysms was detected by DSA and was normal in MSCTA.The sensitivity, specificity, positive predictive value and negative predictive value for detection of aneurysms with MSCTA were 92.9%, 97.1%, 81.3%and99% respectively.Conclusion 3D-MSCTA has important significance in the diagnosis and operation for intracranial aneurysms.