Purpose: Cartilage degeneration or defective repair after an injury is typically associated with changes in the macromolecular composition of cartilage. The major function of large aggregating glycosaminoglycans (GAGs) is hydration of the cellular matrix, ensuring cartilage resiliency through electrostatic repulsion. A decrease in GAGs is likely to expose cartilage to dehydration, predisposing the joint to further degeneration. In parallel, roughening of the articular surface may also occur as a result of cartilage fibrillation, a process involving loosening of the collagen network, denaturation of the collagen and loss of the collagen fiber organization. Such a complex matrix makes any progression or repair of the defect challenging to monitor. New MRI developments allowing for a combined evaluation of both macromolecules are considered as a non-invasive alternative to cartilage biopsies. Thus, recent reports suggest that GAG chemical exchange saturation transfer (gagCEST) and T2 mapping MRI sequences are well suited for the detection of change in GAGs and collagen content and structure, respectively. However, clinical proof is still required to monitor cartilage degeneration after injury using biochemical MRI methods. Therefore, the purpose of this study is to establish sensitivity and reproducibility of quantitative imaging biomarkers, such as gagCEST asymmetry values and T2 relaxation times values of the superficial and deep layers of cartilage. Combined MRI measurements were performed in patients with an acute cartilage injury likely to worsen during the observational period due to several risk factors. Methods: Imaging sessions were performed on 7 patients with cartilage defect(s) in the knee joint (ICRS grade 1 or 2) as well as high risk factors (concomitant meniscus damage and/or ligament instability) for further progression of defect. Cartilage gagCEST and T2 images (Fig.1) were obtained for all patients at 7T using following MRI sequences and acquisition parameters: a 3D RF-spoiled GRE sequence with a resolution of 0.9x0.9x2.2 mm3 for gagCEST imaging, and a 3D-TESS sequence with a resolution of 0.25x0.25x3 mm3 for T2 mapping. For image analysis, regions-of-interest were defined on 2D-TSE morphological images in the suspicious regions for defective and normal appearing cartilage, and transferred to gagCEST and T2 images for quantitative analysis. All MRI measurements were repeated 8 days later for reproducibility assessment Results: The gagCEST asymmetry values (N=5 , preliminary data) were 28% lower in damaged areas as compared to adjacent healthy regions in cartilage (3.06±2.18% vs 4.27±1.61%, p=0.17). Disruption in the zonal organization of collagen fibrils was also observed in the damaged areas. T2 relaxation values becoming more uniform between the superficial and deep cartilage layers in defect region ([superficial/deep]T2 ratio in the defective region: 0.81±0.22 vs in the healthy region: 0.68±0.10, p=0.08). Both, gagCEST and T2 measurements showed high correlation between baseline and day-8 values (r=0.78 and r=0.86 , both p<0.0005, respectively). Conclusions: Both MRI methods, as applied here in combination to patients with low-grade cartilage injury, appear to be reproducible and might be able to detect differences between a defective and healthy region of cartilage. These preliminary results support the use of a comprehensive MRI approach in observational and therapeutic trials to differentiate early formation of hyaline from fibrotic cartilage without resorting to serial biopsies.