title: Duplex ultrasonography in assessing restenosis of renal artery stents.
abstract: OBJECTIVE
  To determine the accuracy and optimal threshold values of duplex ultrasonography (US) in assessing restenosis of renal artery stents.
  
  
  METHODS
  Twenty-four consecutive patients with 33 renal arteries that had previously been treated with placement of a Palmaz stent underwent duplex US prior to intraarterial digital subtraction angiography (DSA), which was the reference standard. Diagnostic accuracy of in-stent peak systolic velocity (PSV) and reno-aortic ratio (RAR = PSV renal stent/PSV aorta) in detecting > 50% in-stent restenosis were evaluated by the receiver operating characteristic curve. Sensitivity and specificity were determined using the optimal threshold values, and using published threshold values: RAR > 3.5 and in-stent PSV > 180 cm/sec.
  
  
  RESULTS
  Six examinations were technically inadequate. Nine stents had residual or restenosis > 50% at DSA. The two duplex parameters were equally accurate since areas under the curves were similar (0.943). With optimal threshold values of 226 cm/sec for PSV and 2.7 for RAR, sensitivities and specificities were 100% and 90%, and 100% and 84%, respectively. Using the published duplex criteria resulted in sensitivities and specificities of 100% and 74% for PSV, and 50% and 89% for RAR.
  
  
  CONCLUSIONS
  Duplex US is a sensitive modality for detecting in-stent restenosis if laboratory-specific threshold values are used.
authors.affiliation: Department of Radiology, University Hospital Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Bakker
authors.forename: J J
authors.initials: JJ
authors.lastname: Beutler
authors.forename: O E
authors.initials: OE
authors.lastname: Elgersma
authors.forename: E E
authors.initials: EE
authors.lastname: de Lange
authors.forename: G A
authors.initials: GA
authors.lastname: de Kort
authors.forename: F J
authors.initials: FJ
authors.lastname: Beek
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D012008:Recurrence; D012077:Renal Artery / Q000000981:diagnostic imaging; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging* / Q000628:therapy*; D012680:Sensitivity and Specificity; D015607:Stents; D018616:Ultrasonography, Doppler, Duplex