title: High-resolution 3D unenhanced ECG-gated respiratory-navigated MR angiography of the renal arteries: comparison with contrast-enhanced MR angiography.
abstract: OBJECTIVE
  The aim of this study is to determine the diagnostic value of high-resolution 3D unenhanced ECG-gated respiratory-navigated MR angiography (MRA) of the renal arteries using a steady-state free precession (SSFP) technique in comparison with 1.0-molar contrast-enhanced MRA in patients with suspected renal artery stenosis.
  
  
  METHODS
  Forty-five consecutive patients underwent unenhanced MRA before contrast-enhanced MRA within the same session. We assessed examination time, image quality, renal artery architecture, and localization and severity of renal artery stenosis.
  
  
  RESULTS
  Examination time was shorter for contrast-enhanced MRA (mean ± SD, 12 ± 3 minutes) than for unenhanced MRA (19 ± 3 minutes; p < 0.001). On a 5-point scale, the image quality was similar for contrast-enhanced MRA (3.8 ± 1.0) and unenhanced MRA (4.0 ± 1.3; p = 0.24). Contrast-enhanced MRA offered more assessable data sets than did unenhanced MRA (95% vs 90%); however, unenhanced MRA had more data sets with maximum image quality (49% vs 30%). There was moderate agreement in stenosis grading between both MRA techniques (κ = 0.51; p < 0.001), but in only one case (1.3%) we found mismatch of more than one severity stenosis grade (stenoses > 75%). Sensitivity, specificity, and positive and negative predictive values of unenhanced MRA to detect renal artery stenoses greater than 50% were 75%, 99%, 75%, and 99%, respectively.
  
  
  CONCLUSIONS
  We show that SSFP 3D unenhanced MRA is a very promising technique for patients with suspected renovascular disease and could be used as an alternative if gadolinium-based contrast agents cannot be administered.
authors.affiliation: University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg, Germany. mohrs@radiologie-darmstadt.de
authors.forename: Oliver K
authors.initials: OK
authors.lastname: Mohrs
authors.forename: Steffen E
authors.initials: SE
authors.lastname: Petersen
authors.forename: Thomas
authors.initials: T
authors.lastname: Schulze
authors.forename: Michael
authors.initials: M
authors.lastname: Zieschang
authors.forename: Harald
authors.initials: H
authors.lastname: Küx
authors.forename: Peter
authors.initials: P
authors.lastname: Schmitt
authors.forename: Sabine
authors.initials: S
authors.lastname: Bergemann
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003287:Contrast Media; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds; D011237:Predictive Value of Tests; D012078:Renal Artery Obstruction / Q000175:diagnosis*; D055425:Respiratory-Gated Imaging Techniques; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol