INNOVATIVE IMAGING TECHNIQUES TO ENHANCE THE QUALITY OF YOUR PRACTICE
Fig. 7. Transverse ultrasound image and corresponding MR image of the proximal branch of the SL at the level of the fourth tarsal bone. The MRI is oriented to match the US image with the dorsal at the bottom of the image.
6. The Effect of Beam Angle
The complicated anatomy of the SL requires addi- tional US techniques to be employed for complete visualization of the ligament and to correctly iden- tify its anatomy (Fig. 8). One of the challenges of SL US is that the regions of fat and muscle create variations in the ligament echogenicity. This echo pattern makes it difficult to determine if these vari-
ations in echogenicity are the result of injury or the normal SL anatomy. A technique that can be used to correctly identify regions of SL fibers versus areas of fat and muscle is called off-angle or oblique inci- dence imaging. The beam angle affects the echoge- nicity of soft tissue structures with linear fibers, which is apparent every time we adjust the angle of the US probe proximally or distally in order to create
Fig. 8. Series of reference images showing the SL origin to the body with on- and off-beam angle imaging using the medial and plantar approaches. The SL is only outlined in certain images to allow better assessment on the nonmarked images. The MRI and gross images are oriented to match the ultrasound images.
