Modified version of the scale by Heckmatt et al. for the visual semi-quantitative assessment of muscle echogenicity

Grade 0 = normal (i.e. normal hypoechoic muscle); Grade 1 = mild (i.e. increased echogenicity in ≤ one-third of muscle tissue); Grade 2 = moderate (i.e. increased echogenicity in > one-third but ≤ two-thirds of muscle tissue); Grade 3 = severe (i.e. increased echogenicity in > two-thirds of muscle tissue). f: femur; rf: rectus femoris muscle; vi: vastus intermedius muscle.