Clinical application of biochemical imaging of cartilage

Articular cartilage injuries are common findings within different joints and patients benefit from optimal diagnosis and treatment. Magnetic resonance imaging (MRI) has become the method of choice for diagnosis of chondral injuries and for the follow-up of patients after cartilage repair surgery. Comparably in degenerative cartilage diseases, MRI is getting more and more important in the description and especially the quantification of the cartilage loss/damage. Here besides the morphological description of the specific cartilage pathology, the assessment of the biochemical status of the cartilage is in the focus of recent research as well as clinical applications. Thus, early and precise diagnosis of ultra-structural cartilage alterations, together with modern surgical treatment options, may offer a possibility for patients with cartilage defects to avoid OA or to delay the progression of OA. The present article provides an overview of issues around the use of biochemical imaging in the clinic setting in the knee and the hip joint. The current state of the art of biochemical MRI in patients with cartilage injuries or after cartilage repair will be discussed as well as the use of biochemical MR techniques in early OA and degenerative cartilage changes. The ultra-structure of repair cartilage can be assessed noninvasively by means of biochemical MRI techniques such as delayed Gadolinium-enhanced MRI of cartilage (dGEMRIC), T2 mapping, T1 rho, diffusion-weighted imaging, or other techniques. These new MR methodologies as well as their sensitivity to specific components of articular cartilage will be provided and discussed in a clinical background.