Evaluation of airway obstruction using virtual endoscopy

Objectives: This study examines the use of virtual endoscopy (VE) in the ev aluation of patients with upper airway obstruction. The utility of VE compa red with actual endoscopy was investigated with respect to accuracy of diag nosis and reproduction of endoscopic images. Study Design: A random cohort of 30 patients with various causes of airway obstruction was examined. Meth ods: The computed tomography (CT) data were reconstructed using a proprieta ry VE software program, FreeFlight, blind to the actual endoscopic findings . The cause of obstruction was identified and compared with actual endoscop ic findings. This included 21 patients with airway stenoses, 8 patients wit h laryngotracheomalacia, 3 tracheal tumors, 2 glottic webs, 5 patients with innominate artery compression, 2 tracheal granulomas, and 7 patients with impaired true vocal cord mobility. Results: Virtual endoscopic evaluation w as accurate in assessing stenosis width and length of fixed airway lesions. Correlation of stenosis shape and contour between actual endoscopy and VE was excellent. The stenosis-to-lumen ratios were compared between VE and ac tual endoscopy and were found to be within 10% (SD = 8). However, virtual e ndoscopic evaluation could not illustrate one of the glottic webs, half of the cases of tracheomalacia, or any of the cases of impaired true vocal cor d mobility. Conclusions: Virtual endoscopy was not as sensitive as actual e ndoscopy in detecting the cause of airway obstruction that was based on dyn amic movement. However, VE was excellent for the measurement and definition of fixed airway lesions.