Effect of contrast agent charge on visualization of articular cartilage using computed tomography: exploiting electrostatic interactions for improved sensitivity.

The synthesis and evaluation of a new class of cationic iodinated contrast agents for the imaging of cartilage using computed tomography (CT) are described. In direct comparisons with anionic contrast agents, the cationic contrast agents afforded higher equilibrium concentrations in the articular cartilage of ex vivo rabbit femurs and thus greater imaging sensitivity. Variations in CT intensity across the sample reflected the inhomogeneous distribution of glycosaminoglycans in the tissue as confirmed by histological analysis. We anticipate that this work represents the first step in the development of sensitive, nondestructive CT-based methods to characterize the biochemical properties of cartilage using cationic contrast agents.