Abstract
Objective—To develop a method to discriminate between structure-related echoes and echoes resulting from interference, as observed in transverse ultrasonographic images of equine superficial digital flexor (SDF) tendons.
Sample Population—2 normal (injury-free) SDF tendons obtained from a 3-year-old Thoroughbred and a 9-year-old Dutch Warmblood horse.
Procedure—Tendons were mounted in a custommade device that permitted exact transverse and perpendicular sequential scanning with precise steps of 0.5 mm along the long axis of the tendon. Photographs of ultrasonographic images of transverse tendon sections at the exact scanning locations were obtained. Propagation, reflection, and refraction artifacts were quantified, and an image rectification procedure was developed, allowing exact matching of each photograph with the corresponding ultrasonographic image. A correlation routine was developed that departed from this transverse ultrasonographic image (position 0); this routine added information from images collected at precise distances of 0.5 and 1 mm on both sides of the actual scan location (positions –2, –1, +1, +2).
Results—By use of the correlation routine, echoes that remained steady over all 5 images were enhanced and resolved, and constantly changing echoes were multiplicatively reduced and faded. This correlated image could be projected over the rectified photograph, and the resolved echoes matched perfectly with the endotendon septa surrounding fibers and fasciculi.
Conclusions and Clinical Relevance—The correlation routine permits exclusive resolution of structurerelated echoes, as echoes resulting from interference are faded. The technique described can produce images that depict only the essential structure-related information. In this way, the clinical assessment of tendon integrity is greatly facilitated. (Am J Vet Res 1999;60:202–209)
