title: Isotropic high spatial resolution magnetic resonance angiography of the supra-aortic arteries using two-dimensional parallel imaging (iPAT2) at 3 Tesla: a feasibility study.
abstract: OBJECTIVE
  We sought to assess the feasibility of isotropic 3-dimensional contrast-enhanced magnetic resonance angiography (MRA) covering the supra-aortic and intracranial arteries with a MR sequence using parallel-imaging in phase- and slice-encoding directions.
  
  
  METHODS
  Six volunteers and 5 patients with suspected cerebrovascular disease were examined at 3.0 T using a 16-element head-neck array. Contrast-enhanced 3-dimensional MRA (repetition time 3.2 milliseconds, echo time 1.2 milliseconds, flip angle 30 degrees , bandwidth 390 Hz/pixel) was acquired with integrated generalized autocalibrating partially parallel acquisition (GRAPPA), in both phase- and slice-encoding direction. Images were evaluated independently by 2 radiologists. Signal-to-noise ratio was calculated from phantom measurements.
  
  
  RESULTS
  Signal-to-ratio levels of 8.7 +/- 2.2/48.7 +/- 10.2 with and without parallel-imaging (GRAPPA x 6) were measured, respectively. Scoring of image quality by observer 1/observer 2 on a 4-point-scale (range 0-3) yielded 2.5 +/- 1.0/2.4 +/- 1.0 and 2.1 +/- 1.0/2.0 +/- 1.1 for extracranial and intracranial vessel segments in volunteers and 2.8 +/- 0.6/2.7 +/- 0.7 and 2.0 +/- 1.2/2.1 +/- 1.1 in patients, respectively. The interobserver agreement was excellent (k = 0.82).
  
  
  CONCLUSIONS
  This study shows that contrast-enhanced MRA, applying parallel-imaging in both phase- and slice-encoding direction (iPAT), is feasible at 3.0 T. Coverage of the carotid and vertebro-basilar circulation was achieved.
authors.affiliation: Department of Diagnostic Radiology, Eberhard-Karls-University, Tuebingen, Germany. michael.fenchel@med.uni-tuebingen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Fenchel
authors.forename: Kambiz
authors.initials: K
authors.lastname: Nael
authors.forename: Stefan
authors.initials: S
authors.lastname: Ruehm
authors.forename: J Paul
authors.initials: JP
authors.lastname: Finn
authors.forename: Stephan
authors.initials: S
authors.lastname: Miller
authors.forename: Gerhard
authors.initials: G
authors.lastname: Laub
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002561:Cerebrovascular Disorders / Q000175:diagnosis*; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media