Psoriatic arthritis: what ultrasound can provide us.

Ultrasound (US) is a valuable imaging technique for detection and characterisation of the inflammatory process in arthritides. US has widely been applied to psoriatic arthritis (PsA) in both clinical and research fields, especially focusing on enthesitis. US has proven to be useful to establish a diagnosis of PsA, to recognise subclinical involvement, (such as enthesis abnormalities in patients with PsA, and in patients with only clinically apparent skin psoriasis despite the absence of clinical symptoms of arthritis), to estimate disease activity, and to allow therapy monitoring showing structural and inflammatory changes (not only in joints and tendons, but also in domains not assessed in usual rheumatology care, such as the skin and nails).