Lung volume determination by dual-source computed tomography in infants with pulmonary artery sling: a case-control study

Abstract

Background: Pulmonary artery sling (PAS) is associated with tracheal stenosis and left pulmonary artery (LPA) dysplasia in infants, both developmental abnormalities that may lead to pulmonary hypoplasia and lung volume changes. As such, we aimed to monitor the effects of tracheal stenosis and pulmonary vascular malformation on lung volumes in infants with PAS and their correlation with lung volumes in infants with PAS using dual-source computed tomography (DSCT).

Methods: A case-control study was performed. From May 2009 to June 2017, we retrospectively enrolled patients with surgically confirmed PAS and compared them to matched normal controls (A healthy control group comprising age- and gender-matched patients with adequate imaging data was used for the comparisons.). All the patients underwent DSCT examinations. We measured and compared the diameters of the trachea, main bronchus, and main pulmonary artery (MPA) and its branches, and both lung volumes on the axial, and reconstructed CT images.

Results: There were no statistical differences in the diameters of the MPA or right pulmonary artery (RPA) between patients (N=15) and controls (N=28). The diameter of the main bronchus, the bilateral trachea and the left pulmonary artery were all smaller in the PAS group than in the control group, and significant differences were evident in the left lung volume the right lung volume, and the right-to-left lung volume ratio between the 2 groups. Pearson's correlation and linear regression analyses between the diameters of the trachea and MPA, total lung volume, ipsilateral bronchial and pulmonary artery branches, and ipsilateral lung volume ranged from 0.71 to 0.87 and 0.57 to 0.77 for the control and PAS groups, respectively.

Conclusions: Tracheal stenosis and LPA dysplasia in infants with PAS cause alterations in lung tissue morphology and physiological development, resulting in reduced bilateral lung volumes.

Keywords: Lung volume; dual-source computed tomography (DSCT); pulmonary artery sling (PAS).

Figure 1

A set of images about the measured trajectories of the aorta, pulmonary artery and trachea. A shows the pulmonary artery diameter (line 1); B shows the diameter of the left pulmonary artery (line 1), a line tangent to the opening of the left pulmonary artery (line 3), and a line parallel to the long axis of the left pulmonary artery (line 2); C shows the diameter of the right pulmonary artery (line 1) tangent to the right border of the ascending and descending aorta (line 3) and a line parallel to the long axis of the right pulmonary artery (line 2); D shows the trachea diameter (line 1); E shows the diameter of left bronchus(line 1), the long axis of the left trachea(line 2). AA, aorta ascendens; AD, aorta descendens; MPA indicates main pulmonary artery; LPA, left pulmonary artery; RPA, right pulmonary artery.

Figure 2

Measurement of left lung volumes in different planes (the pink area represents the lung volume measurement range). Schematic diagram of coronal position (A), sagittal position (B), and transverse position (C).

Figure 3

Statistical results of the PAS and control groups. Scattergrams for the PAS and control groups showing the linear regression results between the tracheal and total lung volume (A), left bronchus and left lung volume (B), right bronchus and right lung volume (C), MPA and total lung volume (D), the LPA and left lung volume (E), and the RPA and right lung volume (F). The Pearson’s correlation coefficients in the PAS group were r=0.59 (P=0.0199), r=0.57 (P=0.0275), and r=0.69 (P=0.0047), respectively; in the control group, they were r=0.87 (P<0.001), r=0.72 (P<0.001), and r=0.83 (P<0.001), respectively. In the PAS group, the results were r=0.62 (P<0.05), r=0.59 (P<0.05), and r=0.77 (P<0.001), respectively. In the control group, the results were r=0.76 (P<0.001), r=0.71 (P<0.001), and r=0.84 (P<0.001), respectively. PAS, Pulmonary artery sling; MPA indicates main pulmonary artery; LPA, left pulmonary artery; RPA, right pulmonary artery.