title: Renal artery stenosis: comparative assessment by unenhanced renal artery MRA versus contrast-enhanced MRA.
abstract: OBJECTIVE
  To evaluate steady-state free precession (SSFP) non-contrast-enhanced MR angiography (Unenhanced-MRA) versus conventional contrast-enhanced MR angiography (CE-MRA) in the detection of renal artery stenosis (RAS).
  
  
  METHODS
  Retrospective analysis of 70 consecutive patients referred for suspected RAS, examined by SSFP Unenhanced-MRA and CE-MRA. Image quality, quality of visible renal arterial segments, presence and grade of RAS were evaluated. The Unenhanced-MRA were compared against reference standard CE-MRA results.
  
  
  RESULTS
  149 renal arteries were assessed with 21 haemodynamically significant stenoses (≥ 50% stenosis) demonstrated by CE-MRA. Combined sensitivity and specificity for RAS detection by Unenhanced-MRA was 72.8% and 97.8% respectively. There is substantial correlation for RAS detection between Unenhanced-MRA and CE-MRA with kappa values of between 0.64 and 0.74. There was excellent inter-observer correlation for RAS on Unenhanced-MRA (kappa values 0.82-1.0).
  
  
  CONCLUSIONS
  Our study has shown Unenhanced-MRA to be a viable alternative to CE-MRA, yielding images equal in quality without the requirement for gadolinium contrast agents. The sensitivity and specificity for the detection of haemodynamically significant stenoses are comparable to CE-MRA. Potentially, Unenhanced-MRA could be used as an initial investigation to avoid performing CE-MRA in patients with normal renal arteries, however we suggest that its real value will lie in being complementary to CE-MRA.
authors.affiliation: Department of MRI, St Mary's Hospital, Imperial College NHS Trust, London, UK. Michael@khoo.me.uk
authors.forename: Michael M Y
authors.initials: MM
authors.lastname: Khoo
authors.forename: Dhafer
authors.initials: D
authors.lastname: Deeab
authors.forename: Wladyslaw M W
authors.initials: WM
authors.lastname: Gedroyc
authors.forename: Neil
authors.initials: N
authors.lastname: Duncan
authors.forename: David
authors.initials: D
authors.lastname: Taube
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Dick
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012078:Renal Artery Obstruction / Q000175:diagnosis*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media