title: High-spatial-resolution MR angiography of renal arteries with integrated parallel acquisitions: comparison with digital subtraction angiography and US.
abstract: OBJECTIVE
  To retrospectively compare three-dimensional gadolinium-enhanced magnetic resonance (MR) angiography, performed with an integrated parallel acquisition technique for high isotropic spatial resolution, with selective digital subtraction angiography (DSA) and intravascular ultrasonography (US) for accuracy of diameter and area measurements in renal artery stenosis.
  
  
  METHODS
  The study was approved by the institutional review board, and consent was obtained from all patients. Forty-five patients (17 women, 28 men; mean age, 62.2 years) were evaluated for suspected renal artery stenosis. Three-dimensional gadolinium-enhanced MR angiograms were acquired with isotropic spatial resolution of 0.8 x 0.8 x 0.9 mm in 23-second breath-hold with an integrated parallel acquisition technique. In-plane diameter of stenosis was measured along vessel axis, and perpendicular diameter and area of stenosis were assessed in cross sections orthogonal to vessel axis, on multiplanar reformations. Interobserver agreement between two radiologists in measurements of in-plane and perpendicular diameters of stenosis and perpendicular area of stenosis was assessed with mean percentage of difference. In a subset of patients, degree of stenosis at MR angiography was compared with that at DSA (n = 20) and intravascular US (n = 11) by using Bland-Altman plots and correlation analyses.
  
  
  RESULTS
  Mean percentage of difference in stenosis measurement was reduced from 39.3% +/- 78.4 (standard deviation) with use of in-plane views to 12.6% +/- 9.5 with use of cross-sectional views (P < .05). Interobserver agreement for stenosis grading based on perpendicular area of stenosis was significantly better than that for stenosis grading based on in-plane diameter of stenosis (mean percentage of difference, 15.2% +/- 24.2 vs 54.9% +/- 186.9; P < .001). Measurements of perpendicular area of stenosis on MR angiograms correlated well with those on intravascular US images (r(2) = 0.90).
  
  
  CONCLUSIONS
  Evaluation of cross-sectional images reconstructed from high-spatial-resolution three-dimensional gadolinium-enhanced MR renal angiographic data increases the accuracy of the technique and decreases interobserver variability.
authors.affiliation: Institute of Clinical Radiology, Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany. stefan.schoenberg@med.uni-muenchen.de
authors.forename: Stefan O
authors.initials: SO
authors.lastname: Schoenberg
authors.forename: Johannes
authors.initials: J
authors.lastname: Rieger
authors.forename: Christof H
authors.initials: CH
authors.lastname: Weber
authors.forename: Henrik J
authors.initials: HJ
authors.lastname: Michaely
authors.forename: Tobias
authors.initials: T
authors.lastname: Waggershauser
authors.forename: Carina
authors.initials: C
authors.lastname: Ittrich
authors.forename: Olaf
authors.initials: O
authors.lastname: Dietrich
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015901:Angiography, Digital Subtraction; D000800:Angioplasty, Balloon / Q000706:statistics & numerical data; D016477:Artifacts; D003287:Contrast Media; D003627:Data Interpretation, Statistical; D019160:Endosonography; D005260:Female; D005682:Gadolinium; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000706:statistics & numerical data; D015588:Observer Variation; D012078:Renal Artery Obstruction / Q000175:diagnosis* / Q000628:therapy; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D015607:Stents / Q000706:statistics & numerical data
chemical_list: D003287:Contrast Media; D005682:Gadolinium