Anterior cruciate ligament (ACL) disruption is a common injury, particularly in the young and active patient. ACL reconstruction surgery is the current standard of care, yet reinjury rates are high, and it does not significantly reduce the risk of post‐traumatic osteoarthritis (PTOA) relative to non‐operative management. A prerequisite for improving interventions is the development of robust measures of ACL healing that directly measure structural properties of the healing ligament or graft. A potential solution is quantitative magnetic resonance imaging (qMRI), which measures soft tissue structural properties, tissue degeneration, and relates to long‐term risk factors.
Objective measures of ACL healing will enable the identification of modifiable risk factors to improve surgical outcomes. Furthermore, it will allow for the comparison of intervention methods with a shorter feedback loop than long‐term outcomes tracking (e.g., registry data). However, widespread adoption of qMRI has been limited outside of research settings, due to challenges such as the inter‐ scanner reproducibility of qMRI sequences, and the time and expertise requirements associated with post‐processing steps such as image segmentation.
The primary goal of this work was to create and validate an automated qMRI pipeline that addresses the key technical bottlenecks for qMRI of the ACL. First, the inter‐scanner reproducibility of two common qMRI sequences (T₂* relaxometry and CISS) was assessed, and post‐acquisition harmonization methods were evaluated to address the observed differences. Second, a deep learning‐ based image segmentation method for the ACL was developed, which automates the most time‐ consuming post‐processing step for qMRI and eliminates the inter‐ and intra‐segmenter variability inherent to manual image segmentation. Third, it was shown that common qMRI features relate prospectively to functional outcomes post‐ACL surgery. Fourth, an improved T₂* relaxometry‐based machine learning model for ACL failure load prediction was developed. Finally, the processing components validated in Aims 1-4 were integrated into a single platform to enable fully automated post-processing of qMRI data. By increasing the practicality of qMRI, the platform created in this project aids in the development of more effective interventions for ACL injury.