title: Tracheal torsion assessed by a computer-generated 3-dimensional image analysis predicts tracheal self-expandable metallic stent fracture.
abstract: OBJECTIVE
  Self-expandable metallic stents are used to relieve airway stenosis in selected patients; however, fracture of these stents may occur. This analysis aims to investigate the extent of tracheal torsion, assessed by a computed-generated reformatted 3-dimensional tracheal reconstruction from 2-dimensional computed tomographic images in predicting fracture of tracheal self-expandable metallic stents.
  
  
  METHODS
  From 2001 to 2007, 32 patients (aged 62.8 ± 14.1 years) with benign tracheal diseases received chest computed tomographic evaluation and Ultraflex (Boston Scientific, Natick, Mass) self-expandable metallic stents. The bending angles of the central axis and peripheral wall of the trachea at choke point were measured from the computed-generated 3-dimensional tracheal images.
  
  
  RESULTS
  Seventeen fractured stents were found among the patients. The median time for stent fracture was 865 days after implantation. Receiver operating characteristic curve analysis revealed that a 19° bending angle of the tracheal central axis (area under the curve, 0.929; 95% confidence interval, 0.847-1.012; P < .001) and a 44° maximal bending angle of the peripheral tracheal wall (area under the curve, 0.918; 95% confidence interval, 0.821-1.012; P < .001) had maximal power in predicting tracheal fracture of self-expandable metallic stents.
  
  
  CONCLUSIONS
  Three-dimensional tracheal reconstructions from 2-dimensional chest computed tomographic data are useful in assessing the severity of tracheal torsion. Tortuous trachea with a central axis bending angle of 19° or more and peripheral tracheal wall maximal bending angle of 44° or more were associated with a high probability of fracture of the self-expandable metallic stent.
authors.affiliation: Department of Thoracic Medicine, Chang Gung Memorial Hospital, and School of Medicine, Chang Gung University, Taipei, Taiwan.
authors.forename: Chih-Teng
authors.initials: CT
authors.lastname: Yu
authors.forename: Chun-Liang
authors.initials: CL
authors.lastname: Chou
authors.forename: Fu-Tsai
authors.initials: FT
authors.lastname: Chung
authors.forename: Jei-Tsai
authors.initials: JT
authors.lastname: Wu
authors.forename: Yuan-Chang
authors.initials: YC
authors.lastname: Liu
authors.forename: Yun-Hen
authors.initials: YH
authors.lastname: Liu
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Lin
authors.forename: Shu-Min
authors.initials: SM
authors.lastname: Lin
authors.forename: Horng-Chuang
authors.initials: HC
authors.lastname: Lin
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Wang
authors.forename: Han-Pin
authors.initials: HP
authors.lastname: Kuo
authors.forename: Hao-Cheng
authors.initials: HC
authors.lastname: Chen
authors.forename: Chien-Ying
authors.initials: CY
authors.lastname: Liu
mesh_terms: D000368:Aged; D001999:Bronchoscopy; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D053208:Kaplan-Meier Estimate; D008297:Male; D008670:Metals; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D015607:Stents; D013624:Taiwan; D014057:Tomography, X-Ray Computed; D014102:Torsion Abnormality / Q000150:complications / Q000000981:diagnostic imaging*; D054159:Torsion, Mechanical; D014132:Trachea / Q000000981:diagnostic imaging*; D014135:Tracheal Stenosis / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D008670:Metals