Tracheal torsion assessed by a computer-generated 3-dimensional image analysis predicts tracheal self-expandable metallic stent fracture

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.