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.
Sample Population—2 damaged and 2 structurally
normal superficial digital flexor tendons.
Procedure—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 and Clinical Relevance—Stability of
echo patterns accurately reflects homogeneity of tendons
in horses. (Am J Vet Res 2003;64:366–375)
Objective—To evaluate effectiveness of computerized
discrimination between structure-related and
non–structure-related echoes in ultrasonographic
images for quantitative evaluation of tendon structural
integrity in horses.
Sample Population—4 superficial digital flexor tendons
(2 damaged tendons, 2 normal tendons).
Procedure—Transverse ultrasonographic images that
precisely matched histologic sections were obtained
in fixed steps along the long axis of each tendon.
Distribution, intensity, and delineation of structurerelated
echoes, quantitatively expressed as the correlation
ratio and steadiness ratio , were compared with
histologic findings in tissue that was normal or had
necrosis, early granulation, late granulation, early
fibrosis, or inferior repair.
Results—In normal tendon, the even distribution of
structure-related echoes with high intensity and sharp
delineation yielded high correlation ratio and steadiness
ratio. In areas of necrosis, collapsed endotendon
septa yielded solid but blurred structure-related
echoes (high correlation ration and low steadiness
ratio). In early granulation tissue, complete lack of
organization caused zero values for both ratios. In late
granulation tissue, reorganization and swollen endotendon
septa yielded poorly delineated structurerelated
echoes (high correlation ratio, low steadiness
ratio). In early fibrosis, rearrangement of bundles
resulted in normal correlation ration and slightly low
steadiness ratio. In inferior repair, the almost complete
lack of structural reorganization resulted in heterogeneous
poorly delineated low-intensity echoes
(low correlation ratio and steadiness ratio).
Conclusions and Clinical Relevance—The combination
of correlation ratio and steadiness ratio accurately
reflects histopathologic findings, making computerized
correlation of ultrasonographic images an efficient
tool for quantitative evaluation of tendon structural
integrity. (Am J Vet Res 2001;62:1159–1166)
Objective—To evaluate quantitative ultrasonography for objective monitoring of the healing process and prognostication of repair quality in equine superficial digital flexor (SDF) tendons.
Animals—6 horses with standardized surgical lesions in SDF tendons of both forelimbs.
Procedures—Healing was monitored for 20 weeks after surgery by use of computerized ultrasonography. Pixels were categorized as C (intact fasciculi), B (incomplete fasciculi), E (accumulations of cells and fibrils), or N (homogenous fluid or cells). Four scars with the best quality of repair (repair group) and 4 scars with the lowest quality (inferior repair group) were identified histologically. Ratios for C, B, E, and N in both groups were compared.
Results—During 4 weeks after surgery, lesions increased 2- to 4-fold in length and 10-fold in volume. Until week 3 or 4, structure-related C and B ratios decreased sharply, whereas E and N ratios increased. After week 4, C and B ratios increased with gradually decreasing E and N ratios. At week 12, C and B ratios were equivalent. After week 12, C ratio increased slowly, but B ratio more rapidly. At week 20, C ratio remained constant, B ratio was substantially increased, and E and N ratios decreased. Values for the inferior repair group were most aberrant from normal. Ratios for C differed significantly between repair and inferior repair groups at weeks 16 and 18 and for B beginning at 14 weeks.
Conclusions and Clinical Relevance—Computerized ultrasonography provided an excellent tool for objective monitoring of healing tendons in horses and reliable prognostication of repair quality.