Hello, Diagnosis of myopathy is not done on basis of MRI findings. The typical algorithm followed for myopathy diagnosis is 1. Clinical pattern. -- Weakness of proximal muscles of limbs. 2. Clinical signs -- Pseudo hypertrophy of muscles. Loss of reflexes. 3. Blood investigation -- Marked increase in CPK levels in serum. 4. EMG -- This is a test done for knowing resting muscle electrical activity and muscles response to stimulation. 4. Muscle biopsy - this is the final test to be done. Helps diagnose and define type of myopathy.