A novel grey scale and Power Doppler ultrasonographic score for idiopathic inflammatory myopathies: Siena Myositis Ultrasound Grading Scale

Objectives No clear-cut guidelines exist on the use of diagnostic procedures for idiopathic inflammatory myopathies (IIM) and only minimal and conflicting data report the use of ultrasound (US). In this regard, we aimed to assess if grey-scale (GS) and Power Doppler (PD) US, graded with a 0-3-point scale, may be a reliable tool in a cohort of patients affected by IIM. Methods All patients underwent US examination of both thighs in axial and longitudinal scans. Oedema and atrophy, both assessed in GS and PD, were graded with a 0-3-point scale. Spearman's test was used to identify the correlations between US and clinical and serological variables. Results A total of 20 patients were included. Six and two patients were evaluated twice and three times, respectively. Muscle oedema was found to be directly correlated with physician global assessment (PhGA), serum myoglobin and PD and negatively with disease duration. PD score was positively correlated to PhGA and negatively to disease duration. Muscle atrophy directly correlated with Myositis Damage Index, disease duration and patient's age. The single-thigh sub-analysis evidenced a direct correlation between PD score and Manual Muscle Test. Conclusions In our cohort, we found that oedema and PD are strictly related to early, active myositis, suggesting that an inflamed muscle should appear swollen, thickened and with Doppler signal. Conversely, muscle atrophy reflects the age of the patient and the overall severity of the disease. Such findings shed a new, promising, light on the role of US in diagnosis and monitoring of IIMs.