Imagerie du rhumatisme psoriasique

Abstract

Imaging is one of the keys to diagnosing psoriatic arthritis. The different modalities will make it possible to highlight the key elements of the disease and its specificity in relation to other spondyloarthritis. This distinction concerns both axial and peripheral lesions, particularly dactylitis. First of all, the standard radiograph which visualizes periostitis present on the epiphyses or phalanges, a diagnostic element in the CASPAR classification criteria, but also juxta-articular erosions which make psoriatic arthritis one of the two chronic inflammatory erosive joint diseases with rheumatoid arthritis. The other anomalies such as acro-osteolysis, joint ankylosis, which are close to osteoarticular destruction on the same anatomical structure, hand or foot, are perfectly identified on the standard images. Ultrasound and MRI have made it possible to describe enthesitis and its capsulo-ligamentary and bony relationships, describing a true anatomical complex. These extra-articular inflammatory attacks are occurring often early in the disease course. Bone damage in the form of bone oedema is the prerogative of MRI to the sacroiliac joints and the spine, in the entheses areas, as in axial ankylosing spondylitis. Spinal damage includes C1-C2 damage like that of rheumatoid arthritis, multi-stage syndesmophytes, which are often larger and coarser, para-syndesmophytes, and radiological or MRI sacroiliitis, which is often less extensive and unilateral. The progression of peripheral joint lesions, erosions and joint space narrowing, is the hallmark of symmetrical or asymmetrical psoriatic polyarthritis.