Articular Cartilage-From Basic Science Structural Imaging to Non-Invasive Clinical Quantitative Molecular Functional Information for AI Classification and Prediction.

This review presents the changes that the imaging of articular cartilage has undergone throughout the last decades. It highlights that the expectation is no longer to image the structure and associated functions of articular cartilage but, instead, to devise methods for generating non-invasive, function-depicting images with quantitative information that is useful for detecting the early, pre-clinical stage of diseases such as primary or post-traumatic osteoarthritis (OA/PTOA). In this context, this review summarizes (a) the structure and function of articular cartilage as a molecular imaging target, (b) quantitative MRI for non-invasive assessment of articular cartilage composition, microstructure, and function with the current state of medical diagnostic imaging, (c), non-destructive imaging methods, (c) non-destructive quantitative articular cartilage live-imaging methods, (d) artificial intelligence (AI) classification of degeneration and prediction of OA progression, and (e) our contribution to this field, which is an AI-supported, non-destructive quantitative optical biopsy for early disease detection that operates on a digital tissue architectural fingerprint. Collectively, this review shows that articular cartilage imaging has undergone profound changes in the purpose and expectations for which cartilage imaging is used; the image is becoming an AI-usable biomarker with non-invasive quantitative functional information. This may aid in the development of translational diagnostic applications and preventive or early therapeutic interventions that are yet beyond our reach.

Articular Cartilage Imaging in the Context of the Superficial Chondrocyte Spatial Organization (SCSO) as a Surrogate Marker for Functional Pathology.

Articular cartilage imaging has undergone tremendous changes and nowadays enables functionally relevant quantitative information useful for detecting the early, preclinical state of articular cartilage degeneration as seen in primary or post-traumatic osteoarthritis (OA/PTOA) to be obtained. In this context, we describe the necessary steps for articular cartilage imaging with the goal to utilize the superficial chondrocyte spatial organization (SCSO) as a score that is responsive to its environment and dynamically changes during the lifetime of an individual and that can be used as a surrogate marker for loss of articular cartilage surface stiffness on the nanoscale.