title: Direct imaging of the distal dural ring and paraclinoid internal carotid artery aneurysms with high-resolution T2 turbo-spin echo technique at 3-T magnetic resonance imaging.
abstract: OBJECTIVE
  To evaluate the feasibility of the direct visualization of the distal dural ring (DDR) and adjacent anatomic structures in patients with paraclinoid internal carotid artery aneurysms at 3-T magnetic resonance imaging (MRI).
  
  
  METHODS
  Six consecutive patients (1 man, 5 women; mean age, 45.5 years; age range, 34-51 years) who underwent a 3-T MRI examination for the evaluation of 7 paraclinoid carotid artery aneurysms were reviewed retrospectively. MRI scans were acquired using a T2 turbo-spin echo sequence with 2-mm thickness without gap on the coronal plane perpendicular to the diaphragma sellae. Identifications of the DDR, adjacent regional anatomic landmarks, and paraclinoid aneurysms were analyzed. The locations of the paraclinoid aneurysms were categorized into intradural (aneurysm neck and sac located above the DDR), transdural (aneurysm neck or sac were straddling the DDR), and extradural (aneurysm neck and sac located below the DDR). Interstudy agreement between computed tomographic angiography and 3-T MRI for the anatomic location of the paraclinoid aneurysms was assessed in 6 patients who underwent both examinations.
  
  
  RESULTS
  In all cases, the DDR was clearly identified and the relationship between the DDR and the paraclinoid aneurysm was successfully determined on 3-T MRI. The aneurysm locations determined with 3-T MRI were 4 intradural and 3 extradural. A comparison between computed tomographic angiography and 3-T MRI revealed discordant anatomic locations in 3 aneurysms (3 of 6, 50%).
  
  
  CONCLUSIONS
  Direct visualization of the DDR as well as precise evaluation of paraclinoid aneurysm location with high-resolution 3-T MRI is possible. This study shows that high-resolution 3-T MRI is an important means to determine the appropriate management for patients with paraclinoid aneurysms.
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, Toronto, Canada.
authors.forename: Laurent
authors.initials: L
authors.lastname: Thines
authors.forename: Seon Kyu
authors.initials: SK
authors.lastname: Lee
authors.forename: Amir R
authors.initials: AR
authors.lastname: Dehdashti
authors.forename: Ronit
authors.initials: R
authors.lastname: Agid
authors.forename: Robert A
authors.initials: RA
authors.lastname: Willinsky
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Wallace
authors.forename: Karel G
authors.initials: KG
authors.lastname: Terbrugge
mesh_terms: D000328:Adult; D000783:Aneurysm / Q000150:complications / Q000175:diagnosis*; D000792:Angiography / Q000379:methods; D002340:Carotid Artery Diseases / Q000150:complications / Q000175:diagnosis*; D002343:Carotid Artery, Internal / Q000473:pathology*; D004388:Dura Mater / Q000473:pathology*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged