Imaging of joints in systemic lupus erythematosus

Musculoskeletal symptoms are among the most common manifestations in patients with systemic lupus erythematosus (SLE), being reported in up to 95% of patients; joint and tendon involvement can range from arthralgia to severe deforming arthropathy; while myositis a rare manifestation, comorbid fibromyalgia is reported in up to 40% of SLE patients. All these manifestations have a significant impact on the patients' quality of life, possibly leading to disability and functional impairment in daily living activities. In recent years, thanks to the availability of new imaging techniques for the assessment of tendon and joint pathologies, the approach to the definition and characterisation of these manifestations in SLE is constantly evolving. In this review we will therefore illustrate the state of the art of imaging techniques in the assessment of joint involvement in SLE, focusing on ultrasounds (US) and magnetic resonance (MRI), discussing their advantages, drawbacks and possible future developments. The main findings that emerge from the recent literature is that imaging studies may allow a more accurate definition of disease subtypes revealing an unexpected higher prevalence of joint and tendon involvement with respect to what known by clinical evaluation and standard radiography. Indeed, US and MRI also made possible the identification of joints and tendons pathologies in patients with no or very mild clinical symptoms. On the other hand, the interpretation of some findings remains uncertain, as well as the validity and feasibility of this analysis in clinical practice. Thus, further studies should clarify the clinical meaning of subclinical abnormalities detected in US and MRI scans and their impact on the long-term outcomes.