Association between respiratory volumes estimated from free-breathing dynamic MRI and sagittal spinal curvature in pediatric patients with thoracic insufficiency syndrome

Thoracic Insufficiency Syndrome (TIS) presents significant challenges in pediatric patients due to skeletal abnormalities that impair thoracic mobility and lung function. Surgical interventions like the Vertical Expandable Prosthetic Titanium Rib (VEPTR) aim to mitigate these effects by enhancing thoracic expansion. This study proposes using free-breathing dynamic MRI (dMRI) to estimate respiratory volumes and assess their correlation with sagittal spinal curvature in pediatric TIS patients. We retrospectively analyzed 98 datasets from 49 pediatric TIS patients who underwent VEPTR surgery, with both pre- and post-operative data collected at the Children’s Hospital of Philadelphia. Using a 3T MRI scanner, thoracic dMRI scans were acquired, generating 4D images for real-time lung ventilation visualization. Segmentation of thoracic components was performed at end-inspiration (EI) and end-expiration (EE) to derive static and tidal volumetric parameters. Statistical analysis revealed significant improvements in respiratory volumes post-operatively, with the right hemidiaphragm tidal volume showing the greatest increase (ratio 1.68). Pearson correlation analysis indicated significant positive correlations between thoracic kyphosis and right-sided respiratory volumes. However, no significant correlations were found between lumbar lordosis and respiratory volumes. These findings suggest that thoracic kyphosis has a notable impact on respiratory function, predominantly on the right side. The use of dMRI provides a valuable, non-invasive method for assessing respiratory function and guiding therapeutic strategies in pediatric TIS patients.