Reproducibility of Forced Expiratory Tracheal Collapse:

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 mm² at Yr1 and 255.1 ± 52 mm² at Yr2; mean dynamic expiratory CSA was 125.6 ± 60 mm² at Yr1 and 132.1 ± 58 mm² 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 mm² for end-inspiratory CSA, 6.5 mm² for dynamic expiratory CSA, and 3.0% for percentage expiratory reduction. There was excellent correlation between the Yr1 and Yr2 measures of end-inspiratory CSA (r² = 0.97, P < .001), dynamic expiratory CSA (r² = 0.89, P < .001), and % expiratory reduction (r² = 0.86, P < .001).

Conclusion

MDCT measurements of forced expiratory tracheal collapse in healthy volunteers are highly reproducible over time.

Key Words: Tracheomalacia, MDCT, reproducibility