Potential of molecular imaging of cartilage

MRI has the potential to provide information regarding the molecular state of cartilage in both bench and clinical studies. MRI indices of cartilage collagen and glycosaminoglycan (GAG) are both potentially available, and a combination of techniques will most likely provide a fuller assessment of cartilage state than either alone. As a paradigm of the type of information available from MRI, the dGEMRIC technique, which provides a measure of GAG distribution, is reviewed in this article. dGEMRIC demonstrates good correlations with known biochemical and biomechanical properties of the tissue. Furthermore, the dGEMRIC index demonstrates measurable and reproducible changes with physiologic and pathologic processes in vitro and in vivo, opening the possibility for studies of molecular effects of disease progression and therapeutic interventions longitudinally in living cartilage. With continued development and with added insight from pilot clinical studies, these or related methods are on the horizon for customary use.