Evaluation of ultrasound in juvenile idiopathic arthritis

Abstract

Juvenile idiopathic arthritis (JIA), the most common rheumatic disease in children, is characterised by joint inflammation (synovitis). Valid methods for detecting and quantifying synovitis, as well as assessing disease activity, are important in the management of patients with JIA. Ultrasound, a well-tolerated and accessible tool, is increasingly being used in the evaluation of synovitis. However, the interpretation of ultrasound findings in children can be challenging due to the unique characteristics of the growing skeleton. In this thesis, Nina Martine Krafft Sande and co-workers developed a standardised ultrasonographic scanning protocol and a semiquantitative joint-specific scoring system for synovitis. Further, they developed an age-divided reference atlas with ultrasound images illustrating the different grades in the scoring system. Then they assessed the reliability and the validity of the scanning protocol and the scoring system with reference atlas. Additionally, Krafft Sande explored Doppler ultrasound findings (blood flow) in joints with synovitis. This is particularly challenging to evaluate in children due to varying degrees of physiological blood flow in joints during growth. The scanning protocol and the scoring system with reference atlas demonstrated moderate to excellent reliability. To evaluate the validity, ultrasound findings of synovitis were compared with whole-body MRI findings of joint inflammation and clinical assessment of disease activity. This showed a moderate to strong correlation. Additionally, Doppler ultrasound findings were associated with other findings of synovitis on ultrasound and with the presence of clinical joint inflammation. The findings indicate that the standardised ultrasonographic scanning protocol and the scoring system with reference atlas are reliable and valid tools and may be valuable in the evaluation of synovitis and disease activity in patients with JIA.