title: Direct duplex scanning parameters in the diagnosis of renal artery stenosis: a study to validate and optimize cut-off points.
abstract: OBJECTIVE
  To test the efficiency of the direct duplex scanning parameters in the diagnosis of renal artery stenosis (RAS), and verify whether or not the cut-off points recommended by medical literature are the most appropriate means to distinguish lesion severity.
  
  
  METHODS
  Prospective study, including 62 patients with RAS, submitted to a duplex ultrasound scan and selective arteriography. The peak systolic velocity (PSV) and the renal-aortic ratio (RAR) were measured. Statistical analysis included the ROC (receiver operating characteristic curve), unpaired students t-test, sensitivity, specificity, positive and negative predictive values and accuracy.
  
  
  RESULTS
  The arteriography revealed RAS 0-59% in 31 arteries (24%); RAS 60-99% in 91 arteries (72%) and 5 occlusions (4%). ROC analysis demonstrated that the lesion detection efficiency of PSV and RAR were similar with areas below the curves of 0.96 and 0.95, respectively. Considering the cut-off points recommended by medical literature, PSV of 180 cm/sec presented a sensitivity of 100% and specificity of 81%, while the RAR of 3.5 presented a sensitivity of only 79%, with a specificity of 93%. These parameters were analyzed in conjunction (direct criteria) revealing a sensitivity of 79% and specificity of 97%. The optimized cut-off points were: PSV of 189 cm/sec and RAR of 2.6, demonstrating sensitivity and specificity rates of 100%, 87%, 96% and 87% respectively.
  
  
  CONCLUSIONS
  The individual use of optimized peak systolic velocity (PSV) was the most efficient parameter in the detection and grading of RAS.
authors.affiliation: Universidade Federal do Rio de Janeiro. carlamcardoso@uol.com.br
authors.forename: Carla Motta
authors.initials: CM
authors.lastname: Cardoso
authors.forename: Sérgio Salles
authors.initials: SS
authors.lastname: Xavier
authors.forename: Gaudencio Espinosa
authors.initials: GE
authors.lastname: Lopez
authors.forename: Tatiana Marlowe Cunha
authors.initials: TM
authors.lastname: Brunini
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging*; D018616:Ultrasonography, Doppler, Duplex