SRS110 - In-vivo magic angle mri imaging reliably identifies collagen fibre orientation in ACL and meniscal tears and may improve the diagnosis of partial ACL tears and meniscal lesions

Introduction Magic Angle Magnetic Resonance Imaging (MA-MRI) exploits the magic angle effect, a phenomenon that generates unique tissue contrast, enabling visualization of individual collagen fibre bundles. Aims To assess ACL and meniscal collagen fibre orientation between conventional MRI and MA-MRI and compare this with the gold standard of arthroscopic findings. Study Design & Methods Ethical approval:ICREC22IC7857,IRAS301889. Volunteers were scanned on both conventional and MA-MRI with a 3DT1FLASH volume taken in seven different scan positions to the main magnetic field (B0). The scanner was rotated into different orientations to obtain a Magic Angle Directional Imaging (MADI) data set. These images were compared with arthroscopic findings. Results A total of 25 participants (18 volunteers, 7 patients; 20 males, 5 females; age range 20–75 years) were scanned.Seven volunteers had pathology with the remaining being healthy. All patients had ACL injuries, partial or complete, and meniscal tears (10). Two had surgical correlation which was in good agreement. Conclusions MA-MRI provides diagnostic information beyond that available from conventional MRI, even at 0.15T. Partial ACL tears detected with MA-MRI showed good correlation with arthroscopic findings, while meniscal tears were visualised as disruptions of the circumferential fibre architecture. MA-MRI may support clinical decision-making for ACL reconstruction or repair by accurately characterising partial injuries. Additionally, imaging of ACL grafts with MA-MRI offers novel, non-invasive insights into graft ligamentisation and integration, with potential implications for predicting return-to-play outcomes.