title: Renal artery stenosis: grading with image-directed Doppler US evaluation of renal resistive index.
abstract: OBJECTIVE
  To determine the role of intrarenal Doppler ultrasound (US) in detection of moderate to severe (> 50%) renal artery stenosis (RAS).
  
  
  METHODS
  In 72 patients, 142 kidneys were examined with conventional angiography and color duplex US. Renal size, mean intrarenal-arterial resistive index (RI), and difference of mean RIs between both kidneys (delta RI) were determined and compared with severity of RAS as determined with quantitative angiography.
  
  
  RESULTS
  In 32 patients, angiography showed mild RAS < or = 50% in 13, moderate RAS in 10, and severe RAS in nine. Both renal size and mean RI values were decreased significantly (P < .001) only for severe RAS compared with values in 40 control subjects. For delta RI, no significant difference was noted between controls and patients with mild RAS; highly significant differences, however, were noted for both moderate and severe RAS (P < .001). Sensitivity and specificity of a cutoff delta RI of > 5% were 82% and 92% for RAS > 50% and 100% and 94% for moderate RAS and RAS > 60%.
  
  
  CONCLUSIONS
  Color Doppler US and analysis of intrarenal Doppler spectra are recommended as a useful method for noninvasive diagnosis and grading of RAS. In bilateral RAS > 50%, however, calculation of delta RI is potentially biased by undergrading of stenosis.
authors.affiliation: Department of Internal Medicine, Philipps-University, Marburg, Germany.
authors.forename: W B
authors.initials: WB
authors.lastname: Schwerk
authors.forename: I K
authors.initials: IK
authors.lastname: Restrepo
authors.forename: M
authors.initials: M
authors.lastname: Stellwaag
authors.forename: K J
authors.initials: KJ
authors.lastname: Klose
authors.forename: C
authors.initials: C
authors.lastname: Schade-Brittinger
mesh_terms: D000792:Angiography; D001783:Blood Flow Velocity / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012077:Renal Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging* / Q000453:epidemiology; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014465:Ultrasonics; D014463:Ultrasonography; D014655:Vascular Resistance / Q000502:physiology