title: Infundibular dilation and aneurysm at the origin of the posterior communicating artery: differential diagnosis by CT angiography.
abstract: BACKGROUND
  Infundibular dilation (ID) and aneurysm at the internal carotid artery (ICA)-posterior communicating artery (PComA) junction can be difficult to distinguish but may differ in clinical significance. The aim of this study was to evaluate the utility of CT angiography (CTA) in differentially diagnosing IDs and small unruptured aneurysms at the ICA-PComA junction.
  
  
  METHODS
  This retrospective study comprised 88 patients diagnosed with 107 protrusions (70 IDs and 37 aneurysms <5 mm; 19 bilateral lesions) at the ICA-PComA junction who underwent both CTA and digital subtraction angiography (DSA). Two neuroradiologists independently reviewed CTA and DSA images according to these criteria: (a) size (maximum dimension <3 or ≥3 mm), (b) shape (triangular or round/oval/irregular), (c) aneurysmal neck (absent or present), (d) horizontal direction (posteriomedial or posteriolateral), and (e) PComA origin (apex, no PComA, or base). The intermodality (between CTA and DSA) and interobserver (between the two readers) agreement were determined for each finding. We also evaluated the sensitivity and specificity of CTA for distinguishing ID and aneurysm, using DSA as the reference standard.
  
  
  RESULTS
  The mean κ values of intermodality agreement for the size, shape, aneurysmal neck, horizontal direction, and PComA origin were 0.88, 0.87, 0.84, 0.71, and 0.56, respectively. All interobserver agreements of CTA and DSA were excellent. The sensitivity, specificity, and accuracy of CTA for differentiating aneurysms from IDs were 94.6, 100, and 98.0 %, respectively.
  
  
  CONCLUSIONS
  CTA may be a useful noninvasive modality for differential diagnosis of ID and aneurysm at the ICA-PComA junction.
authors.affiliation: Department of Radiology, Kangdong Seong-Sim Hospital, Hallym University College of Medicine, 150, Seongan-ro, Gangdong-Gu, Seoul, 134-701, South Korea.
authors.forename: Kyung-Jun
authors.initials: KJ
authors.lastname: Min
authors.forename: Dae-Young
authors.initials: DY
authors.lastname: Yoon
authors.forename: Heung-Chul
authors.initials: HC
authors.lastname: Kim
authors.forename: Jong-Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Byung-Moon
authors.initials: BM
authors.lastname: Cho
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging*; D002343:Carotid Artery, Internal; D002533:Cerebral Angiography; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
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