[Arthritis: imaging and therapy. Past, present and future].

Osteoarthritis (OA) and rheumatoid arthritis (RA) are chronic diseases in which pathological anatomy changes very slowly. Whilst clinical and laboratory measures can be used to evaluate therapeutic response, assessment of disease progression requires imaging. Conventional radiography has performed well in RA but is too insensitive in OA. Never have imaging techniques been discussed which focus on the sites of fundamental pathological change in cartilage and synovia. Such techniques would provide potential end-points for measuring disease progression and the efficacy of therapeutic intervention. Many are non-invasive but are still at a developmental stage. Expense and complexity currently restricts their use to research. However, improving imaging hardware and information technology provide an exciting future for radiologists involved in joint imaging. Clinical trials involving techniques described here are just around the corner.