Whole-body MR imaging in evaluation of children with juvenile dermatomyositis

Purpose: To evaluate the whole-body MRI (WBMRI) findings in children with juvenile dermatomyositis (JDM) and correlate them with clinical and laboratory results. Method: We conducted the present prospective study from October 2019 to September 2021. Thirty children (8.2 ± 3.88 years) with a diagnosis of JDM based on EULAR/ACR classification criteria underwent WBMRI using short tau inversion recovery, diffusion-weighted, and T1 modified DIXON (precontrast and postcontrast) sequences. WBMRI scans were analysed independently by two radiologists for abnormal signal intensity and enhancement in the different muscle groups. Radiological findings were correlated with clinical examination, muscle enzymes, and inflammatory markers. Results: WBMRI revealed abnormal signal intensity and diffusion restriction, predominantly in the thigh (n = 21, 70 % children), calf (n = 18, 60 % children), and hip (n = 16, 53.3 % children) muscles. A significant positive correlation was observed between the serum total creatinine kinase and lactic dehydrogenase levels, with altered signal intensity and diffusion restriction in the paraspinal and thigh muscles. Diffusion restriction in the hip and calf muscles also showed significant positive correlations with these enzymes. Significant positive correlations were detected between lower limb muscle strength and altered signal intensity and diffusion restriction in the thigh (p = 0.023) and calf (p = 0.002) muscles. Postcontrast images did not yield any additional useful information. Conclusions: WBMRI provided useful information in evaluation of the extent and distribution of findings in children with JDM. There were significant positive correlations between MRI findings and muscle enzymes and clinical examination results. The addition of contrast to the WBMRI protocol did not provide any additional advantage.