title: Contrast-enhanced MR angiography of supraaortic vessels: the effect of voxel size on image quality.
abstract: OBJECTIVE
  Several acquisition strategies may be used for imaging supraaortic vessels by using contrast-enhanced MR angiography. The purpose of this study was to assess the effect of voxel size on image quality of MR angiograms.
  
  
  METHODS
  Fourty-four patients underwent 3D MR angiography in the coronal plane. Patients were randomly assigned into two groups according to the voxel size of MR angiograms: group 1 referred to a 1.3 x 1.29 x 1.25-mm voxel size and group 2 to a 0.95 x 0.76 x 0.82 mm voxel size. Signal-to-noise ratios (SNRs) were measured and image artifacts were analyzed by consensus between observers. The delineation of the arterial lumen was independently ranked on a four-point scale (1 = not assessable; 2 = poor delineation; 3 = fair delineation; 4 = optimal delineation).
  
  
  RESULTS
  The overall interobserver agreement for the delineation of the arterial lumen was good (K = .84, P < .0001), with a rank significantly higher in group 2 (68% of arteries graded as 4) compared with group 1 (76% graded as 3). SNRs were significantly higher by using the conventional resolution technique, with a negative correlation between SNRs and artery delineation (P < .0001). Image artifacts, however, were more frequent with the high-resolution technique, including wrap-around artifacts and signal fall-off at the origin of the great vessels.
  
  
  CONCLUSIONS
  MR angiograms with a decreased voxel size improve the delineation of cervical carotid and vertebral arteries, despite reduced SNRs and additional artifacts.
authors.affiliation: Department of Neuroradiology, Hôpital Roger Salengro, University Hospital of Lille, France.
authors.forename: X
authors.initials: X
authors.lastname: Leclerc
authors.forename: L
authors.initials: L
authors.lastname: Nicol
authors.forename: J Y
authors.initials: JY
authors.lastname: Gauvrit
authors.forename: V
authors.initials: V
authors.lastname: Le Thuc
authors.forename: D
authors.initials: D
authors.lastname: Leys
authors.forename: J P
authors.initials: JP
authors.lastname: Pruvo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D002339:Carotid Arteries / Q000033:anatomy & histology*; D003287:Contrast Media; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods* / Q000592:standards*; D008297:Male; D008875:Middle Aged; D009333:Neck; D015588:Observer Variation; D014711:Vertebral Artery / Q000033:anatomy & histology*
chemical_list: D003287:Contrast Media