Quantitative muscle ultrasonography in the follow‐up of juvenile dermatomyositis

INTRODUCTION: We explored the use of quantitative muscle ultrasonography (QMUS) for follow-up of juvenile dermatomyositis (JDM). METHODS: Seven JDM patients were evaluated at diagnosis and 1, 3, 6, 12, and 24 months using the Childhood Myositis Assessment Scale (CMAS) and QMUS. Muscle thickness (MT) and quantitative muscle echo intensity (EI) were assessed with QMUS in 4 muscles. RESULTS: Six patients experienced a monocyclic course. At diagnosis EI was slightly increased, and MT was relatively normal. After start of treatment MT first decreased and EI increased, with normalization of EI within 6-12 months (n = 4). One patient had higher EIs at diagnosis and slower normalization, indicating fibrosis, despite early normalization of CMAS. One patient experienced a chronic course, with high EIs and atrophy during follow-up. CONCLUSIONS: QMUS can provide additional information for follow-up of JDM regarding disease severity and residual muscle damage, particularly after normalization of CMAS.