Magnetic resonance imaging in spondyloarthritis--how to quantify findings and measure response.

Sensitive and reliable tools for monitoring disease activity and damage, and for prognostication, are essential in the management of patients with spondyloarthritis, including ankylosing spondylitis and psoriatic arthritis. Magnetic resonance imaging (MRI) allows direct visualisation of inflammation in peripheral and axial joints, and peripheral and axial entheses, and has dramatically improved the possibilities for early diagnosis and objective monitoring of the disease process in spondyloarthritis. Truthful, discriminative and feasible scoring systems are available for the assessment of inflammatory activity in the spine and sacroiliac joints in axial spondyloarthritis and in the hands of patients with peripheral psoriatic arthritis. Various systems for assessment of damage in axial and peripheral joints are available, but further studies are needed to document their value in clinical trials and clinical practice. The present article reviews key aspects of the status and recent important advances in MRI in spondyloarthritis, focussing on available MRI tools for assessing activity and damage in peripheral and, particularly, axial joints.