The Effect of Body Postural Changes on the Relationship Between Pulmonary Tissue and Rib Deformation: A Study Based on High-Resolution CT and 3D Reconstruction

Background: The accurate localization of pulmonary nodules is significantly influenced by body positional changes, which also have a profound impact on lung morphology. As the body position changes, alterations in lung morphology are closely associated with shifts in the thoracic cage structure. However, the relationship between rib morphology and pulmonary tissue deformation has not been thoroughly explored. This study aims to investigate the relationship between lung tissue deformation and rib movement during the transition from the supine to the left lateral decubitus position. To achieve this, we employed computed tomography (CT) imaging and three-dimensional (3D) reconstruction techniques. Methods: Eleven healthy male volunteers received high-resolution CT scans in both the supine and left lateral decubitus positions. Lung volumes and morphological characteristics were assessed using 3D reconstruction software. Simulated pulmonary nodules were created, and the distances between the centroids of these nodules and the rib centerline coordinates were measured. Paired t-tests were conducted to evaluate the differences in lung volume, morphology, and rib deformation between the two positions. Results: In the left lateral decubitus position compared to the supine position, significant increases were observed in the volumes of the right upper lobe, right lower lobe, and total right lung, while the right middle lobe exhibited no significant change. Lung height and hemidiaphragm height showed significant increases, whereas lung width and depth remained relatively stable. The deformation relationships between the right upper and middle lobes and the ribs were minimal, with a maximum variation of 13 mm. In contrast, significant differences were identified between the right lower lobe and the ribs, with a maximum discrepancy of 27 mm. Conclusion: The transition from the supine to the left lateral decubitus position has a significant impact on lung volumes and morphological parameters, especially in the right lower lobe. The relationship between pulmonary tissue deformation and rib movement is relatively consistent in the right upper and middle lobes, but substantial differences are observed in the right lower lobe. These discrepancies are likely due to a combination of increased lung volume, lobar sliding, and rib deformation.