Evaluation of Tracheal Index in Obstructive Airway Disease Using High Resolution Computed Tomography (HRCT)
Purpose: To assess the change in Tracheal index in patients of COPD as a function of severity and its correlation with PFT parameters.
Methods: HRCT scans of 48 patients were done and correlated with Pulmonary Function Tests taken within 2 weeks of the study. We obtained TI by dividing the coronal diameter of the trachea by sagittal diameter and multiplying it by 100 at a level 2 cm above the aortic arch. These values were then correlated with COPD severity based on PFT results.
Results: The mean tracheal index in our study was 0.672 ± 0.10. The mean tracheal index in mild emphysema group was 0.73 ± 0.07 and in the moderate to severe group 0.61 ± 0.08. A significant correlation was found between tracheal index and PFT parameters signifying COPD severity i.e. FEV1, FEV1/FVC, RV/TLC and Pef 25%-75%.
Conclusion: Tracheal index is a marker of severity of COPD and it has significant association with the PFT parameters in these patients. Large airway changes in COPD patients can predict lung function and small airway changes.