Imaging in the diagnosis and management of peripheral psoriatic arthritis-The clinical utility of magnetic resonance imaging and ultrasonography

Psoriatic arthritis (PsA) is an inflammatory joint disease characterised by the presence of arthritis and often enthesitis and/or spondylitis in patients with psoriasis. However, it presents a wide range of disease manifestations in various patterns. Imaging is an important part of management of PsA, and is used for multiple reasons including establishing/confirming a diagnosis of inflammatory joint disease, determining the extent of disease, monitoring activity and damage, assessing therapeutic efficacy, and identifying complications of disease or treatment, in the setting of clinical practice or clinical studies. Magnetic resonance imaging (MRI) allows detailed assessment of all peripheral and axial joints involved in PsA, and can visualise both inflammation and structural changes. Ultrasonography (US) can visualise many of the peripheral heterogeneous tissue compartments affected by PsA. In contrast to MRI, US is not useful for assessing axial involvement in the spine and sacroiliac joints. In this paper, we will provide an overview of the status, strengths and limitations of MRI and US in peripheral PsA in routine clinical practice and clinical trials.