title: CT angiography of intracranial aneurysms: a focus on postprocessing.
abstract: Computed tomographic (CT) angiography is a well-known tool for detection of intracranial aneurysms and the planning of therapeutic intervention. Despite a wealth of existing studies and an increase in image quality due to use of multisection CT and increasingly sophisticated postprocessing tools such as direct volume rendering, CT angiography has still not replaced digital subtraction angiography as the standard of reference for detection of intracranial aneurysms. One reason may be that CT angiography is still not a uniformly standardized method, particularly with regard to image postprocessing. Several methods for two- and three-dimensional visualization can be used: multiplanar reformation, maximum intensity projection, shaded surface display, and direct volume rendering. Pitfalls of CT angiography include lack of visibility of small arteries, difficulty differentiating the infundibular dilatation at the origin of an artery from an aneurysm, the kissing vessel artifact, demonstration of venous structures that can simulate aneurysms, inability to identify thrombosis and calcification on three-dimensional images, and beam hardening artifacts produced by aneurysm clips. Finally, an algorithm for the safe and useful application of CT angiography in patients with subarachnoid hemorrhage has been developed, which takes into account the varying quality of equipment and software at different imaging centers.
authors.affiliation: Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. tomandl@neuroradiologie-erlangen.de
authors.forename: Bernd F
authors.initials: BF
authors.lastname: Tomandl
authors.forename: Niels C
authors.initials: NC
authors.lastname: Köstner
authors.forename: Miriam
authors.initials: M
authors.lastname: Schempershofe
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Huk
authors.forename: Christian
authors.initials: C
authors.lastname: Strauss
authors.forename: Lars
authors.initials: L
authors.lastname: Anker
authors.forename: Peter
authors.initials: P
authors.lastname: Hastreiter
mesh_terms: D000465:Algorithms; D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging*; D000792:Angiography / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D015901:Angiography, Digital Subtraction; D016477:Artifacts; D003116:Color; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D012422:Rupture, Spontaneous; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging / Q000209:etiology; D036542:Tomography, Spiral Computed / Q000295:instrumentation / Q000379:methods* / Q000592:standards