title: Covered transjugular intrahepatic portosystemic shunts: accuracy of ultrasound in detecting shunt malfunction.
abstract: OBJECTIVE
  The purpose of this study was to determine the accuracy of ultrasound for detecting transjugular intrahepatic portosystemic shunt (TIPS) malfunction in covered stents in comparison with bare metal stents.
  
  
  METHODS
  During a 6-year period, 126 TIPS angiography examinations were performed in 78 patients who had undergone a recent TIPS ultrasound examination. Radiology reports and images were retrospectively reviewed, and the sensitivity and specificity of sonographic parameters for detecting TIPS dysfunction were calculated using TIPS angiography and portosystemic gradient as the reference standards.
  
  
  RESULTS
  Of 126 paired studies, 43 were in bare metal TIPS and 83 were in covered TIPS. Peak shunt velocity of covered and bare metal TIPS measured by ultrasound showed comparable sensitivities for detection of shunt dysfunction, using both depressed (< 90 cm/s) and elevated (> 200 cm/s) peak shunt velocity criteria. However, a depressed velocity was more specific in covered TIPS (0.939 vs 0.550, p < 0.001) whereas elevated velocity was more specific in bare TIPS (0.485 vs 0.800, p = 0.041). An interval change in peak TIPS velocity greater than 25% was significantly more sensitive in detection of dysfunction in covered TIPS (0.815 vs 0.400, p = 0.015) whereas detection based on main portal vein velocities (≤ 30 cm/s) was not statistically different in the two groups.
  
  
  CONCLUSIONS
  Our data suggest that the accuracy of ultrasound for detection of TIPS shunt malfunction is at least as high in covered stents as in bare metal stents. Diagnostic performance for several sonographic parameters varied significantly between bare and covered stents, suggesting the need for optimization of sonographic criteria for covered stents.
authors.affiliation: Division of Vascular and Interventional Radiology, Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC 27710, USA.
authors.forename: Bjorn I
authors.initials: BI
authors.lastname: Engstrom
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Horvath
authors.forename: Paul V
authors.initials: PV
authors.lastname: Suhocki
authors.forename: Alastair D
authors.initials: AD
authors.lastname: Smith
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Hertzberg
authors.forename: Tony P
authors.initials: TP
authors.lastname: Smith
authors.forename: Charles Y
authors.initials: CY
authors.lastname: Kim
mesh_terms: D000792:Angiography; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019168:Portasystemic Shunt, Transjugular Intrahepatic / Q000009:adverse effects*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D015607:Stents / Q000009:adverse effects*; D018608:Ultrasonography, Doppler