title: Technical factors of CT angiography studied with a carotid artery phantom.
abstract: OBJECTIVE
  To evaluate scanning parameters (conventional versus spiral CT, section thickness, and pitch) and vessel orientation in the performance of CT angiography.
  
  
  METHODS
  Conventional CT and 1.0-, 1.5-, and 2.0-pitch spiral CT acquisitions of a carotid phantom designed with vessels oriented parallel to the z-axis, 45 degrees oblique, and perpendicular to the z-axis were obtained with section thicknesses of 2, 4, and 8 mm. The phantom contained 32 vessels with 0% to 100% stenoses. Normal and stenotic luminal diameters were measured and the number of artifacts was assessed.
  
  
  RESULTS
  No overall difference was observed among conventional and spiral CT acquisitions obtained with pitches of 1.0, 1.5, and 2.0. With thicker sections, CT angiographic accuracy decreased and artifacts increased. The three-vessel orientations were relatively comparable in accuracy in terms of the percentage of stenosis measured. Vessels parallel to the z-axis suffered less artifactual degradation. Unique artifacts, such as luminal distortion and beam hardening, were observed in vessels oriented at 45 degrees and perpendicular to the z-axis.
  
  
  CONCLUSIONS
  Use of thinner sections with vessels oriented parallel to the z-axis optimizes CT angiographic quality. There is no apparent degradation with the use of spiral CT, and a pitch of 1.5 or 2.0 provides results equivalent to 1.0-pitch spiral studies.
authors.affiliation: Department of Radiology, Penn State University College of Medicine, Hershey 17033, USA.
authors.forename: S W
authors.initials: SW
authors.lastname: Wise
authors.forename: K D
authors.initials: KD
authors.lastname: Hopper
authors.forename: T A
authors.initials: TA
authors.lastname: Schwartz
authors.forename: T R
authors.initials: TR
authors.lastname: Ten Have
authors.forename: C J
authors.initials: CJ
authors.lastname: Kasales
mesh_terms: D002545:Brain Ischemia / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography / Q000295:instrumentation*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*