title: Contrast-enhanced MR angiography of intracranial giant aneurysms.
abstract: OBJECTIVE
  Intravoxel phase dispersion and flow saturation often prevent adequate depiction of intracranial giant aneurysms on 3D time-of-flight (3D-TOF) MR angiography (MRA). Additional diagnostic difficulties may arise from T1 contamination artifact of an associated blood clot. Our aim was to assess whether contrast-enhanced MRA could improve the evaluation of giant aneurysms and to compare two different types of contrast-enhanced MRA.
  
  
  METHODS
  We studied 11 aneurysms in 10 patients (age range, 31-77 years) with giant aneurysms of the anterior (n = 9) and posterior (n = 2) cerebral circulation by comparing 3D-TOF, first-pass dynamic contrast-enhanced MRA, and steady-state contrast-enhanced 3D-TOF sequences. Additional comparison with digital subtraction angiography (DSA) was performed in eight aneurysms.
  
  
  RESULTS
  In nine of 11 aneurysms, 3D-TOF did not adequately show the lumen and exiting vessels. Contrast-enhanced 3D-TOF and dynamic contrast-enhanced MRA showed the aneurysm sac and exiting vessels in all of these cases. Dynamic contrast-enhanced MRA showed a better intravascular contrast than did contrast-enhanced 3D-TOF, which led to better delineation of the aneurysms. T1 contamination artifact from intra- or extraluminal blood clot was evident on the 3D-TOF images in four cases. The artifact was less marked on the contrast-enhanced 3D-TOF image and was completely eliminated on the dynamic contrast-enhanced MRA image by subtraction of precontrast images. The diagnostic information provided by dynamic contrast-enhanced MRA was comparable to that provided by DSA.
  
  
  CONCLUSIONS
  Precontrast 3D-TOF is inadequate for the assessment of giant cerebral aneurysms. Both contrast-enhanced 3D-TOF and dynamic contrast-enhanced MRA reliably show the aneurysm sac and connected vessels. Dynamic MRA provides a superior contrast between flow and background and eliminates T1 contamination artifact. It should therefore be considered as the MRA sequence of choice.
authors: Lysholm Radiological Department, The National Hospital for Neurology and Neurosurgery, The Institute of Neurology Queen Square, London.
authors: H R
authors: HR
authors: Jäger
authors: H
authors: H
authors: Ellamushi
authors: E A
authors: EA
authors: Moore
authors: J P
authors: JP
authors: Grieve
authors: N D
authors: ND
authors: Kitchen
authors: W J
authors: WJ
authors: Taylor
mesh_terms: D000328:Adult; D000368:Aged; D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002532:Intracranial Aneurysm / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged
chemical_list: D003287:Contrast Media