Multi-parametric visualization of knee joint ultra-structure: Validation of biochemical magnetic resonance imaging - from bench to bedside

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Sophisticated surgical techniques for the treatment of cartilage defects, meniscus pathologies, or anterior cruciate ligament (ACL) tears, require high quality follow-up. In addition to conventional morphological magnetic resonance imaging (MRI), compositional (biochemical) MRI is a novel approach for a more comprehensive analysis of joint tissues. However, most biochemical MR techniques have not been sufficiently validated by histomorphological analysis as yet, which limits their applicability in pre-clinical or clinical studies. While visualisation of cartilage by dGEMRIC or T2 relaxation mapping are the subject of current validation studies, the analysis of repaired or degenerative cartilage using newer techniques, such as 23Na(sodium) imaging, T2* mapping, T2d mapping, ultra-short echo-time (UTE) imaging, magnetization transfer contrast (MTC), diffusionweighted imaging (DWI), or T1rho, has, to date, not been satisfactorily validated. Furthermore the implementation of these MR methodologies has not been proven adequately with histological methods for investigating the meniscus or the ACL.The goal of the present grant is to validate these novel MR techniques with histomorphology and ultra high-field (7T) MR microscopy, using two established animal models, and to implement the findings into clinical MR follow-up protocols. In the knee joints of 20 sheep, healthy articular cartilage will be compared with either degenerated articular cartilage induced by meniscectomy, or with two different types of cartilage repair tissues induced by the microfracture technique (MFX), or matrix-associated autologous chondrocyte transplantation (MACT). In addition, the above-mentioned biochemical MR methodologies will be used to assess the associated joint structures, including the menisci and anterior cruciate ligament in a multi-parametric approach at different time points after surgery.