Determination of subcarinal angle of trachea using computed tomography

Abstract

Background: Change in tracheal bifurcation angle (subcarinal angle) is an indirect marker of various cardiac, pulmonary and mediastinal pathologies. Helical computed tomography (CT) allows acquisition of volumetric set of data of the chest and can be used for accurate measurements of subcarinal angle using reconstructed images on a workstation using minimum intensity projection (MinIP).The objective of this study was to estimate normal subcarinal angle (SCA) of trachea by computed tomography and to assess its relationship with gender.Methods: This was an observational study comprising a study cohort of 552 patients comprising of 312 males and 240 females who were subjected to CT chest for various indications in our department. Patients with no underlying cardiac, mediastinal or pulmonary disease were included in the study. Spiral CT scan of chest was performed on 64-slice seimens CT SOMATOM and images were reconstructed with thickness of 1.5mm and the images were viewed in coronal reformatted minimum intensity projection (MinIP) for determination of subcarinal angle using the angle measuring tool provided in the workstationResults: The mean subcarinal angle (SCA) in males was (67.60±14.55). The mean subcarinal angle (SCA) in females was (78.90±11.04). Females had a higher mean SCA compared to males with a statistically significant difference (p-value <0.05).Conclusions: The mean SCA in females was higher compared to males with a statistically significant difference between the two. This study holds practical relevance with regard to the performance of invasive trachea-bronchial procedures like bronchoscopy and tracheal/bronchial intubation.