Computerized ultrasonographic tissue characterization of equine superficial digital flexor tendons by means of stability quantification of echo patterns in contiguous transverse ultrasonographic images.
OBJECTIVE
To describe a method of computerized ultrasonographic tissue characterization that includes structures below the size limits of resolution in equine superficial digital flexor tendons.


METHODS
2 damaged and 2 structurally normal superficial digital flexor tendons.


METHODS
Transverse ultrasonographic images were collected along the tendon long axis. Stability of echo pattern was quantified by means of variation in gray levels of each pixel in contiguous images and expressed as correlation, entropy, and waviness ratios.


RESULTS
Normal young and normal old tissues were characterized by high correlation and low entropy and waviness ratios. In necrotic tissue, collapsed intratendinous septa resulted in high correlation, moderate entropy, and high waviness ratios. In early granulation tissue, complete lack of bundle formation resulted in values of zero for correlation and waviness ratios; loose connective tissue matrix resulted in a high entropy ratio. In late granulation tissue, formation of new bundles resulted in a high correlation ratio; swollen intratendinous septa and incomplete organization of connective tissue matrix were reflected in high entropy and waviness ratios. In early fibrotic tissue, rearrangement of tendon bundles resulted in a correlation ratio within reference range and a slight increase in the waviness ratio; an increase in cellularity and lack of fibrillar arrangement led to an increase in the entropy ratio. In late fibrotic and scar tissues, inferior quality of repair with almost complete lack of organization was reflected in low to moderate correlation, low waviness, and high entropy ratios.


CONCLUSIONS
Stability of echo patterns accurately reflects homogeneity of tendons in horses.
van Schie
Hans T M
HT
Leiden Institute for Advanced Computer Science, Leiden University, Niels Bohrweg 1, 2300 RA Leiden, The Netherlands.
Bakker
Erwin M
EM
Jonker
A Mieke
AM
van Weeren
P Rene
PR
D000375:Aging; D000818:Animals; D005552:Forelimb / Q000000981:diagnostic imaging* / Q000473:pathology; D006734:Horse Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D006736:Horses; D013708:Tendon Injuries / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary; D013710:Tendons / Q000000981:diagnostic imaging* / Q000473:pathology; D014463:Ultrasonography