FIGURE 1.

Visual semi-quantitative scale for the assessment of muscle echogenicity. Ultrasound (US) transverse scan images of the quadriceps muscle obtained at the midpoint between the anterior superior iliac spine and the upper pole of the patella. Grade 0 = normal (i.e., normal hypoechoic muscle); Grade 1 = mild (homogeneously distributed overall increase of the echogenicity involving ≤ one-third of the entire muscle tissue); Grade 2 = moderate (homogeneously distributed overall increase of the echogenicity involving > one-third but ≤ two-thirds of the entire muscle tissue); Grade 3 = severe (homogeneously distributed overall increase of the echogenicity involving > two-thirds of the entire muscle tissue). f, femur; rf, rectus femoris muscle; vi, vastus intermedius muscle.