title: Postinterventional passive expansion of partially dilated transjugular intrahepatic portosystemic shunt stents.
abstract: OBJECTIVE
  To investigate passive transjugular intrahepatic portosystemic shunt (TIPS) stent expansion in patients with intentional "underdilation" (eg, 10-mm stent, 8-mm balloon) during TIPS creation.
  
  
  METHODS
  Custom in-house software was developed for objective quantification of cross-sectional stent area from computed tomography (CT) data. The technique was validated by in vitro experiments. The study included 39 patients (22 men; mean age, 59.2 y) who underwent TIPS creation (VIATORR stent graft [W. L. Gore & Associates, Flagstaff, Arizona]; n = 29; WALLSTENT endoprosthesis [Boston Scientific, Marlborough, Massachusetts], n = 10) with stent underdilation. Follow-up CT data of the patients were used to quantify in vivo stent area changes. Data were analyzed by variance analysis and entered into a general linear model to test for interrelations between stent area changes and clinical (eg, cirrhosis grade) and procedural parameters.
  
  
  RESULTS
  In vitro validation of the in-house software showed good agreement and reproducibility without overestimation of stent area. Mean clinical follow-up time in patients was 787 days (range, 7-2,450 d). At the time of intervention, VIATORR stent grafts and WALLSTENT endoprostheses were dilated to an average of 64.4% ± 2.3% and 65.63% ± 8.52% of nominal area, respectively. At the last imaging follow-up evaluation, this value had increased in all stents to a mean of 87.8% ± 7.9% (VIATORR) and 82.34% ± 19.6% (WALLSTENT) in the TIPS tract (P < .05). Multivariate analysis revealed the time after intervention to be the only predictor of stent area in the TIPS tract. There was no significant association between stent expansion and clinical or procedure-related parameters.
  
  
  CONCLUSIONS
  The area of self-expanding stents implanted in the liver for TIPS creation with dilation to less than nominal diameter significantly increases over time. This increase has to be considered as an additional factor influencing the long-term portosystemic gradient.
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, Bonn 53105, Germany.
authors.forename: Claus Christian
authors.initials: CC
authors.lastname: Pieper
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, Bonn 53105, Germany.
authors.forename: Alois Martin
authors.initials: AM
authors.lastname: Sprinkart
authors.affiliation: Institute for Medical Biometry, Informatics and Epidemiology, University of Bonn, Sigmund-Freud-Strasse 25, Bonn 53105, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nadal
authors.affiliation: Department of Internal Medicine I, University of Bonn, Sigmund-Freud-Strasse 25, Bonn 53105, Germany.
authors.forename: Valerie
authors.initials: V
authors.lastname: Hippe
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, Bonn 53105, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Meyer
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, Bonn 53105, Germany.
authors.forename: Hans Heinz
authors.initials: HH
authors.lastname: Schild
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, Bonn 53105, Germany.. Electronic address: daniel.thomas@ukb.uni-bonn.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004106:Dilatation / Q000295:instrumentation* / Q000379:methods; D019544:Equipment Failure Analysis; D005260:Female; D006499:Hepatic Artery / Q000000981:diagnostic imaging*; D006503:Hepatic Veins / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019168:Portasystemic Shunt, Transjugular Intrahepatic / Q000295:instrumentation* / Q000379:methods*; D011474:Prosthesis Design; D017755:Prosthesis Fitting / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome