title: Accuracy of computed tomography angiography in the diagnosis of intracranial aneurysms.
abstract: OBJECTIVE
  Although digital subtraction angiography (DSA) remains the standard for intracranial aneurysm diagnosis, computed tomography angiography (CTA) is being increasingly used for this purpose. CTA has sensitivities and specificities reported as high as 97% and 100%, respectively. We analyzed a prospective cohort of 112 patients with 134 unruptured aneurysms who underwent community CTAs and confirmatory DSAs in a tertiary facility.
  
  
  METHODS
  Patients referred between 2007 and 2010 (mean age 53.2 years) with aneurysms identified by CTA underwent confirmatory DSA. The results were compared to determine accuracy of CTA in diagnosing aneurysms. Aneurysms diagnosed by CTA but ruled out by DSA or aneurysms missed by CTA but diagnosed by DSA were analyzed by size and location. Anatomical variants leading to false CTA positive results were noted.
  
  
  RESULTS
  CTA identified 132 aneurysms, of which 27 (20.5%) were false positives. Of these 27 aneurysms, 18 were completely negative but 9 had an anatomical structure that explained the CTA finding, 18 were either small (6-10 mm, 4%) or very small (1-5 mm, 63%), and 16 were located either in the anterior communicating artery (ACoA) region (33%) or at the basilar artery bifurcation (26%). Additionally, DSA identified 29 aneurysms (21.6%) missed by CTA. The most common locations for these were the cavernous segment of the internal carotid artery (24%) and the middle cerebral artery (24%), and all but 1 were very small (1-5 mm).
  
  
  CONCLUSIONS
  The CTA accuracy rate may be lower than previously reported. CTA is particularly inaccurate in aneurysms 5 mm or smaller and those in the ACoA region.
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Pradilla
authors.forename: Robert T
authors.initials: RT
authors.lastname: Wicks
authors.forename: Uri
authors.initials: U
authors.lastname: Hadelsberg
authors.forename: Philippe
authors.initials: P
authors.lastname: Gailloud
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Coon
authors.forename: Judy
authors.initials: J
authors.lastname: Huang
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Tamargo
mesh_terms: D015901:Angiography, Digital Subtraction; D020771:Anterior Cerebral Artery / Q000000981:diagnostic imaging; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging; D002533:Cerebral Angiography / Q000379:methods* / Q000706:statistics & numerical data; D015331:Cohort Studies; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging; D011446:Prospective Studies; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data