53-year-old female with proximal muscle weakness. Clinical diagnosis of polymyositis. There is minimal increased signal abnormality on fluid sensitive sequences within the deltoid and biceps brachii muscle bellies proximal to the level of the myotendinous junction, which appear intact. There is no evidence of fatty atrophy of the imaged musculature of the right arm. The remainder of the visualized musculature is normal in appearance. No bone marrow signal abnormality is identified. The visualized tendons are grossly unremarkable. The glenohumeral joint alignment appears to be anatomic.
Slight increased signal abnormality on fluid sensitive sequences within the biceps brachii and deltoid muscle bellies which is nonspecific but can be seen in subacute denervation injury, myositis, as well as in the brachial neuritis.