title: Accuracy of pre- and postcontrast 3D time-of-flight MR angiography in patients with acute ischemic stroke: correlation with catheter angiography.
abstract: OBJECTIVE
  3D time-of-flight (TOF) MR angiography (MRA) is insensitive to slow flow; however, the use of MR imaging contrast agents helps to visualize slow-flow vessels and avoids overestimation of vascular occlusion. The purpose of this study was to correlate pre- and postcontrast 3D TOF MRA with the results of conventional angiography during endovascular reperfusion therapy and to determine the accuracy of postcontrast 3D TOF MRA.
  
  
  METHODS
  Thirteen patients who underwent endovascular reperfusion therapy for acute ischemic stroke were retrospectively analyzed. MR imaging techniques included single-slab 3D TOF MRA with and without contrast, as well as perfusion-weighted imaging. Angiography during reperfusion therapy was used as a standard of reference. Affected arteries were divided into segments either proximal or distal to the lesion, and pre- and postcontrast MRA signals were graded as absent, diminished or narrowed, or normal.
  
  
  RESULTS
  In 2 of 5 patients with arterial stenosis and 6 of 8 patients with complete occlusion, MRA signal intensity proximal to each lesion was absent, indicating a proximal pseudo-occlusion on precontrast MRA. Postcontrast MRA demonstrated an arterial signal intensity proximal to the stenotic or occlusive lesions in all 13 patients. Arterial signal intensity distal to the occlusion was identified on postcontrast MRA in 7 of 8 patients having complete occlusion, and the extent of occlusion on postcontrast MRA was similar to results of conventional angiography.
  
  
  CONCLUSIONS
  In this small series, postcontrast 3D TOF MRA more accurately delineated the extent of stenotic or occlusive arterial lesions than precontrast MRA.
authors.affiliation: Department of Radiology, National Hospital Organization Nagasaki Medical Center, Omura, Japan. ishimaruh@nmc.hosp.go.jp
authors.forename: H
authors.initials: H
authors.lastname: Ishimaru
authors.forename: M
authors.initials: M
authors.lastname: Ochi
authors.forename: M
authors.initials: M
authors.lastname: Morikawa
authors.forename: H
authors.initials: H
authors.lastname: Takahata
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuoka
authors.forename: T
authors.initials: T
authors.lastname: Koshiishi
authors.forename: T
authors.initials: T
authors.lastname: Fujimoto
authors.forename: A
authors.initials: A
authors.lastname: Egawa
authors.forename: K
authors.initials: K
authors.lastname: Mitarai
authors.forename: T
authors.initials: T
authors.lastname: Murakami
authors.forename: M
authors.initials: M
authors.lastname: Uetani
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000175:diagnosis* / Q000628:therapy; D002404:Catheterization; D002533:Cerebral Angiography / Q000379:methods* / Q000592:standards; D002548:Cerebral Revascularization; D002560:Cerebrovascular Circulation; D003251:Constriction, Pathologic; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D020521:Stroke / Q000175:diagnosis* / Q000628:therapy