title: Non-invasive investigations of potential renal artery stenosis in renal insufficiency.
abstract: BACKGROUND
  The diagnostic value of non-invasive methods for diagnosing renal artery stenosis in patients with renal insufficiency is incompletely known.
  
  
  METHODS
  Forty-seven consecutive patients with moderately impaired renal function and a clinical suspicion of renal artery stenosis were investigated with computed tomography angiography (CTA), gadolinium-enhanced magnetic resonance angiography (MRA), contrast-enhanced Doppler ultrasound and captopril renography. The primary reference standard was stenosis reducing the vessel diameter by at least 50% on CTA, and an alternative reference standard ('morphological and functional stenosis') was defined as at least 50% diameter reduction on CTA or MRA, combined with a positive finding from ultrasound or captopril renography.
  
  
  RESULTS
  The frequency of positive findings, calculated on the basis of individual patients, was 70% for CTA, 60% for MRA, 53% for ultrasound and 30% for captopril renography. Counting kidneys rather than patients, corresponding frequencies were 53%, 41%, 29% and 15%, respectively. In relation to the CTA standard, the sensitivity (and specificity) at the patient level was 0.81 (0.79) for MRA, 0.70 (0.89) for ultrasound and 0.42 (1.00) for captopril renography, and at the kidney level 0.76 (0.82), 0.53 (0.81) and 0.30 (0.86), respectively. Relative to the alternative reference standard, corresponding values at the patient level were 1.00 (0.62) for CTA, 0.90 (0.69) for MRA, 0.91 (1.00) for ultrasound and 0.67 (1.00) for captopril renography, and at the kidney level 0.96 (0.76), 0.85 (0.79), 0.71 (0.97) and 0.50 (0.97), respectively.
  
  
  CONCLUSIONS
  CTA and MRA are superior to ultrasound and captopril renography at diagnosing morphological stenosis, but ultrasound may be useful as a screening method and captopril renography for verifying renin-dependent hypertension.
authors.affiliation: Nephrology (IMH), Linköping University, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Eriksson
authors.forename: Ahmed Abdulilah
authors.initials: AA
authors.lastname: Mohammed
authors.forename: Jakob
authors.initials: J
authors.lastname: De Geer
authors.forename: Johan
authors.initials: J
authors.lastname: Kihlberg
authors.forename: Anders
authors.initials: A
authors.lastname: Persson
authors.forename: Göran
authors.initials: G
authors.lastname: Granerus
authors.forename: Fredrik
authors.initials: F
authors.lastname: Nyström
authors.forename: Örjan
authors.initials: Ö
authors.lastname: Smedby
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012015:Reference Standards; D012077:Renal Artery / Q000000981:diagnostic imaging; D012078:Renal Artery Obstruction / Q000175:diagnosis* / Q000473:pathology; D051437:Renal Insufficiency / Q000150:complications*; D014057:Tomography, X-Ray Computed