Reproducibility of Forced Expiratory Tracheal Collapse: Assessment with MDCT in Healthy Volunteers

Rationale and Objectives: To assess the reproducibility of multidetector-row computed tomography (MDCT)-measured forced expiratory tracheal collapse in healthy volunteers. Methods and Materials: Fourteen healthy, nonsmoking volunteers (6 males, 8 females, mean age 48.7 +/- 13.8 years) underwent repeat imaging 1 year after baseline imaging of tracheal dynamics employing the same scanner and technique (64-MDCT, 40 mAs, 120 kVp, and 0.625 mm detector collimation) with spirometric monitoring of total lung capacity and forced exhalation. Cross-sectional area (CSA) of the trachea was measured 1 cm above the aortic arch at end-inspiration and dynamic expiration, and percentage (%) expiratory reduction in tracheal lumen was calculated. Measurements were compared between baseline (Yr1) and repeat imaging (Yr2) using correlation coefficients and Bland-Altman plots. Results: Mean end-inspiratory CSA was 255.3 +/- 56 mm(2) at Yr1 and 255.1 +/- 52 mm(2) at Yr2; mean dynamic expiratory GSA was 125.6 +/- 60 mm(2) at Yr1 and 132.1 +/- 58 mm(2) at Yr2; and mean % expiratory reduction was 51.7 +/- 18% at Yr1 and 48.7 +/- 19% at Yr2. Mean differences between Yr1 and Yr2 values were 0.2 mm(2) for end-inspiratory GSA, 6.5 mm(2) for dynamic expiratory GSA, and 3.0% for percentage expiratory reduction. There was excellent correlation between the Yr1 and Yr2 measures of end-inspiratory GSA (r(2) = 0.97, P < .001), dynamic expiratory GSA (r(2) = 0.89, P < .001), and % expiratory reduction (r(2) = 0.86, P < .001). Conclusion: MDCT measurements of forced expiratory tracheal collapse in healthy volunteers are highly reproducible over time.