Digital radiographic measurement of the main bronchi: a pilot study.

Background: Conventional chest radiographs do not afford consistently good visualisation of the main bronchi and sub-carinal angle. Improved visualisation would facilitate accurate measurement of the airways, definition of normal radiographic anatomy and, possibly, earlier identification of extrinsic compression or displacement.
Aim: The main objective of this study was to establish whether the paediatric main bronchi and sub-carinal angle could be measured consistently on AP supine chest images obtained using a specific digital radiographic system (DRS).
Subjects and Methods: The proximal bronchial diameters were measured on supine DRS chest images of 102 children between the ages of 6 months and 13 years.
Results: The left and right main bronchi could be seen clearly and measured in over 90% of cases, with intraclass correlation co-efficients of reliability indicating high intra- and inter-observer agreement. The sub-carinal angle had lower intra- and inter-observer agreement.
Conclusion: Supine chest images acquired using DRS facilitate accurate measurement of the main bronchi and sub-carinal angle in children. Further work is required to establish population-specific age-related norms for bronchial dimensions. These could serve as reference standards for early detection of deviations from normal.