title: Infundibular dilation: an anatomical variant or a pre-aneurysm? Advantages of assessment with three-dimensional rotational angiography.
abstract: OBJECTIVE
  Whether an infundibular dilation (ID) is an anatomical variant or a pre-aneurysm has not been clearly determined. The aim of the present study was to evaluate the anatomical change of IDs by use of three-dimensional rotational angiography (3DRA) with volume rendering (VR).
  
  
  METHODS
  One-hundred thirty-eight patients with known or suspected aneurysms, treated consecutively, underwent both two-dimensional digital subtraction angiography (2DDSA) and 3DRA with VR. Two readers evaluated the IDs or aneurysms blindly, using 2DDSA and 3DRA, according to the same diagnostic criteria. A 5-point scale of observer confidence was used to determine the presence of IDs or aneurysms. For 3DRA with VR, the relationship between IDs and aneurysms was classified as one of the three types: type I, protrusion or bulge from side wall of IDs; type II, aneurysms involving or enclosing IDs; or type III, aneurysms and IDs coexisting near each other but with some distance between them.
  
  
  RESULTS
  The number of IDs found by 2DDSA and 3DRA with VR was 41 and 48, respectively. Five anterior choroidal arteries and two posterior communicating arteries IDs were missed by 2DDSA. According to 3DRA with VR, there were five IDs of type I, nine of type II, and 22 of type III.
  
  
  CONCLUSIONS
  The 3DRA with VR appears superior to 2DRA for both diagnosing IDs and displaying the anatomical relationship between IDs and aneurysms. The findings also suggest that some IDs might progress to aneurysms or become a part of them, which should be carefully evaluated prior to operation.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, The Sixth Affiliated People's Hospital, Shanghai Jiao Tong University, No 600, Yi Shan Road, Shanghai 200233, China.
authors.forename: Wan-Yin
authors.initials: WY
authors.lastname: Shi
authors.forename: Yong-Dong
authors.initials: YD
authors.lastname: Li
authors.forename: Ming-Hua
authors.initials: MH
authors.lastname: Li
authors.forename: Bin-Xian
authors.initials: BX
authors.lastname: Gu
authors.forename: Wu
authors.initials: W
authors.lastname: Wang
authors.forename: Bei-Lei
authors.initials: BL
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult