Diaphragm motion and shape as a function of the scoliotic spinal curve in thoracic insufficiency syndrome (TIS)

Abstract

Thoracic insufficiency syndrome (TIS) is a rare condition that results in restricted lung growth and impaired respiratory function. Investigation of the impact of scoliotic spinal curve on regional respiratory function in individuals with TIS is important to elucidate the underlying mechanisms behind restricted respiratory function and to optimize effective treatment approaches. However, there are currently no suitable parameters for quantifying pulmonary respiratory function that demonstrate a strong correlation with scoliotic spinal curve. A new study of the relationship between scoliotic spinal curve and diaphragm motion is proposed in this work to uncover how spinal scoliosis impacts respiration, providing new insights into the specific mechanisms for respiratory dysfunction. The diaphragm was delineated at end inspiration (EI) and end expiration (EE) time points in reconstructed 4D images via dynamic MRI, and was divided into left and right hemi-diaphragms. To facilitate the regional description of motion, we partitioned each hemi-diaphragm into 13 distinct regions and computed the velocity and curvature for each of these regions. An analysis was conducted on 26 cases with main thoracic curves (MTC), including 15 cases with right-sided MTC (MTC-R) and 11 cases with left-sided MTC (MTC-L). T-testing comparing the MTC-R group with the MTC-L group revealed the impact of spinal curve sidedness on the motion of the left hemi-diaphragm. The velocity cloud maps exhibited a restriction of left diaphragmatic motion due to leftward spinal curve. Furthermore, correlation analysis demonstrated a significant influence of major curve angles (TCA and LCA) on hemi-diaphragm velocities in specific regions. Such findings improve our understanding of the pathophysiological mechanisms that lead to abnormal respiratory function in TIS.