FIGURE 2.

‘Multimodal’ assessment of quadriceps muscle mass (a), muscle quality (b, muscle echogenicity assessment using ImageJ analysis) and muscle stiffness (c, point shear wave elastography) in two healthy individuals. In figure a, the typical ‘starry night’ appearance of a normal muscle (28–year-old man) can be observed. A transverse approach is preferred for the measurement of muscle thickening (red dashed lines) of the rectus femoris (rf) and vastus intermedius (vi) muscles. Figure b shows a moderate increase in muscle echogenicity in a 55-year-old woman. Muscle echogenicity can be measured using a dedicated image analysis program, which measures the gray scale intensity in a region of interest (ROI) utilizing histogram function (i.e. ImageJ). In the same person, muscle stiffness of the rectus femoris is measured using point shear wave elastography (longitudinal approach) and it is expressed by m/s.