Microstructural magnetic resonance imaging of articular cartilage

Abstract

The focus of this Editorial is recent developments in magnetic resonance imaging (MRI) modalities for evaluation of the microstructure and macromolecular organisation of articular cartilage. We place a specific emphasis on three types of measurements: (1) MRI transverse spin-relaxation mapping (T₂ mapping); (2) diffusion-tensor imaging and (3) compression micro-MRI (μMRI) measurements of articular cartilage in vitro. Such studies have a significant role to play in improving the understanding of the fundamental biomechanics of articular cartilage and in the development of in vitro models of early osteoarthritis. We discuss how the supramolecular organisation of the cartilage extracellular matrix and its behaviour under mechanical compression can be inferred from diffusion-tensor and T₂ maps with in-plane resolution ∼100 μm. The emphasis is on in vitro studies performed under controlled physiological conditions but in vivo applications of T₂ mapping and DTI are also briefly discussed.