Fig. 2.

In vivo ultrasonic measurement of wave speed. a A linear array ultrasound transducer was strapped over the subject’s Achilles tendon. High frame rate (14,100 frames per second) ultrasonic radiofrequency (RF) data were collected at two points (red, blue lines). A custom tapper device (hammer icon; see Supplementary Fig. 2), which was located distal to the ultrasound transducer, intermittently induced transverse waves in the tendon. Center: transverse tissue velocity was measured at multiple kernels (indicated by boxes; darker shades indicate greater depth) located along each RF collection line (red, blue). Scale bar, 1 cm. b We observed that transverse motion was similar for all kernels along the first (red, lower) and second (blue, upper) measurement locations. Thus, tendon wave motion could conceivably be measured from the motion of subcutaneous tissue