title: Localization and Treatment of Unruptured Paraclinoid Aneurysms: A Proton Density MRI-based Study.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the usefulness of proton density magnetic resonance (PD MR) imaging for localization of paraclinoid internal carotid artery aneurysms.
  
  
  METHODS
  From April 2014 to April 2015, 76 unruptured paraclinoid aneurysms in 66 patients were evaluated using PD MR and angiography (CT/MR angiography or digital subtraction angiography). The locations (extradural, transdural, intradural) in relation to the distal dural ring (DDR) and projection (superior, inferior/posterior, medial, lateral) of the aneurysms were assessed and compared.
  
  
  RESULTS
  The most common location of paraclinoid aneurysms was extradural (n = 48, 63.2%), followed by intradural (n = 18, 23.7%), and transdural (n = 10, 13.2%). In the medial projection group (n = 49, 64.5%), 31 were extradural (63.3%), 5 were transdural (10.2%), and 13 were intradural (26.5%). In the inferior/posterior projection group (n = 19, 25.0%), there were 14 extradural (73.7%), 4 transdural (21.0%), and 1 intradural (5.3%). In the superior (n = 4, 5.3%)/lateral (n = 4, 5.3%) projection groups, there were 0/3 extradural (0/75.0%), 1/0 transdural (25.0/0%), and 3/1 intradural (75.0/25.0%).
  
  
  CONCLUSIONS
  PD MR showed sufficient contrast difference to distinguish paraclinoid aneurysms from surrounding dural structures.
authors.affiliation: Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Seon Jin
authors.initials: SJ
authors.lastname: Yoon
authors.affiliation: Department of Radiology, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Na-Young
authors.initials: NY
authors.lastname: Shin
authors.affiliation: Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jae Whan
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Seung Kon
authors.initials: SK
authors.lastname: Huh
authors.affiliation: Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Keun Young
authors.initials: KY
authors.lastname: Park
keywords: Aneurysm; Internal carotid artery; Magnetic resonance imaging