Recently, multi-planar reconstruction of the three-dimensional (3D) spiral chest CT scan has demonstrated superiority in the evaluation of the tracheobronchial tree. The goal of this study was to measure the lengths of the right and left main bronchi and their anteroposterior (AP) and transverse (TR) diameters using the 3D and two-dimensional (2D) images in the same adult respectively, and to evaluate the degree of correlation between them.

We measured the lengths of the right and left main bronchi from the carina to the first of their branches and the AP and TR diameters at the mid-portion of the right main bronchus and 2 cm below the carina in the left main bronchus. We determined the size of the left-sided double-lumen tube (DLT) based on the measured AP diameter of the left main bronchus from the 3D and 2D images, respectively.

There was moderate correlation between the lengths of both main bronchi obtained from the 3D images and the 2D images, and between the AP diameter of the left main bronchus obtained from the 3D images and the 2D images. Same sized DLTs were estimated in 69% of the men and 34% of the women.

The lengths of the right and left main bronchi and their AP and TR diameters obtained from 3D images were not strongly correlated with those from 2D images. Therefore, a further study is needed to verify the superiority of 3D images in selecting the appropriate size of left-sided DLT.