Ultrasonography in the Diagnosis and Follow-up of Idiopathic Inflammatory Myopathies--a Preliminary Study

Objective: To study the utility of ultrasonography (US) in diagnosis and follow up of patients with idiopathic inflammatory myopathy (IIM).

Methods: High-resolution US of thigh muscles was recorded at baseline and after six months of treatment in eleven patients of early, active, untreated IIM. Parameters studied were muscle power, timed function tests (TFT), muscle enzymes, electromyography, muscle histopathology and US parameters such as echogenicity of muscle and perimysial septa count per 1 cm muscle width.

Results: There was a significant increase in muscle echogenicity and septa count of patients as compared to those of controls (p = 0.002 and 0.00003, respectively). These abnormalities resolved on treatment. Muscle echogenicity and perimysial septa count showed mild positive correlation with walking time, 4-step climbing and myopathic pattern on EMG. Perimysial septa count in addition correlated weakly with creatine phosphokinase, lactate dehydrogenase and muscle fibre necrosis.

Conclusion: US seems to be a useful, non-invasive, cheap modality to monitor the disease course in IIM. Larger studies to confirm these primary findings are warranted.