Tracheal Stenosis Caused by Thoracic Malignancy: Correlation between CT-Based Tracheal Measurement and Spirometric Values before and after Tracheal Stenting

Background: The correlation between computed tomography (CT)-based tracheal size and spirometry values is unknown in patients with tracheal stenosis by thoracic malignancy, which is often treated by tracheal stenting. Objectives: To evaluate the correlation between the tracheal cross-sectional area (CSA) and spirometric values before and after tracheal stenting, and to confirm that greater improvement in tracheal CSA leads to a larger improvement in spirometry values. Methods: A total of 32 patients with malignant tracheal stenosis underwent tracheal stenting. Before (n = 32) and after (n = 27) treatment, patients underwent chest CT, measuring mean and minimum tracheal CSA values, and spirometry. The correlation between tracheal CSA and each spirometric value was evaluated using Spearman rank correlation analysis. Differences in the pre- and posttreatment tracheal CSA and spirometric values were evaluated using the Wilcoxon matched-pairs test. Results: Significant improvement in the minimum tracheal CSA and in spirometric values was observed after stenting (P < 0.001). Pretreatment analysis revealed significant correlations between the minimum tracheal CSA and various spirometric values (P < 0.01), but posttreatment analysis showed weak or insignificant correlations. The increase in the minimum tracheal CSA obtained by stenting was significantly correlated with improvement in multiple spirometric values (P < 0.05). Conclusions: The tracheal size measured on chest CT correlates with patients’ spirometric values, particularly at the prestenting examination, in patients with malignant tracheal stenosis. The increase in the minimum tracheal CSA after stenting on CT is a predictor for improved spirometric values, which is first demonstrated by this study.