Contrast-Enhanced Computed Tomography Reflects Stiffness of Intact Articular Cartilage

Purpose: Articular cartilage distributes load in joints and provides a low-friction surface for joint movement. Glycosaminoglycan (GAG) in cartilage plays a critical role in its compressive stiffness. Loss of GAG is an early sign of osteoarthritis that leads to lower compressive stiffness and altered viscoelastic behavior. MRI and CT-based imaging techniques have been developed to quantify GAG content in cartilage in an effort to detect osteoarthritic changes early in the disease process. Contrast-Enhanced Computed Tomography (CECT) attenuation using a custom cationic contrast agent (CA4+) correlates with GAG content and equilibrium compressive modulus in bovine osteochondral plug. CA4+ demonstrates higher sensitivity to changes in GAGs than commercially available anionic contrast agents. Applicability of these results to in vivo human studies is not clear because the cartilage is nonhuman and the plug model affects both diffusion of the contrast agent and cartilage mechanics.