Evaluating laryngotracheal stenosis in a canine model with virtual bronchoscopy

We performed a prospective masked animal study to determine whether virtual bronchoscopy, a noninvasive computed tomography technique, can accurately measure upper airway stenosis. Virtual bronchoscopy creates a 3-dimensional endoscopic image from spiral computed tomography data. Laryngotracheal stenosis was endoscopically induced in 18 dogs. The excised larynges were examined by endoscopy, virtual bronchoscopy, and macrodissection. Measurements were made of the anteroposterior (A-P) diameter, the left-right (L-R) diameter, the full length of stenosis in the sagittal plane, and the length of the tightest stenotic segment. Each measurement method was performed independently. All investigators were unaware of measurements made by others. The measurements obtained through virtual bronchoscopy and actual endoscopy were compared to those made at dissection by interclass correlation coefficients (ICCs). Endoscopy was better than virtual bronchoscopy in measuring the A-P diameter (ICC = .79, p < .0001; ICC = .42, p = .01). Both were equally effective in measuring the L-R diameter (ICC = .53, p = .0062; ICC = .52, p = .0064). The endoscopes could not assess the full length of the stenosis, whereas virtual bronchoscopy measured it fairly accurately (ICC = .72, p = .0001). Virtual bronchoscopy relatively accurately measured the length of the tightest stenotic segment (ICC = .68, p = .0002), whereas endoscopy produced measurements in only 11 of 18 larynges, and the measurements were less accurate (ICC = .45, p = .0068). Virtual bronchoscopy can provide good measurements of stenotic lesions in the airway. It is more accurate than actual endoscopy in determining the length of stenosis. It may therefore be useful as an adjunct imaging method in preoperative planning for reconstructive surgery.