Ultrasound axial image of the wrist

This is an ultrasound axial image of the wrist at the distal wrist crease. The image on the left is obtained with the probe perpendicular to the flexor carpi radialis tendon (T); note that it is hyperechoic in this image. In the right image, at the same level, the probe is tilted just off the perpendicular axis by aiming the probe slightly proximal. Note that this shift of just a few degrees causes the tendon to become hypoechoic. The median nerve (N) varies less in echogenicity because the tendon exhibits a higher degree of anisotropy. Note that some of the flexor tendons below the nerve, which are not precisely parallel to the flexor carpi radialis tendon, also show marked variations in echogenicity with the slight shift of probe angle. (The numeral "-1" to the right indicates a depth of 1 cm, and the dot below it represents an additional 0.5 cm.)