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- Author or Editor: Hans T. M. van Schie x
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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)
Abstract
Objective—To correlate quantitative analysis of ultrasonographic images of normal (injury-free) equine superficial digital flexor (SDF) tendons and equine SFD tendons that have pathologic changes with corresponding histologic sections.
Sample Population—4 SDF tendons, 2 of which had various stages of tissue integrity. The 2 ipsilateral tendons were used as points of reference.
Procedure—Tendons were mounted in a custommade device that permitted sequential scanning, transversely and perpendicular to the tendon long axis. At precise steps of 0.5 mm, transverse ultrasonographic images were collected. Subsequently, tendons were fixed and prepared for histologic examination. The following 8 tissue types were discerned: normal young, normal old, necrotic, early granulation, late granulation, early fibrotic, late fibrotic, and scar tissues. In areas of interest, the corresponding ultrasonographic images were selected for gray level statistical analysis.
Results—Compared with other tissue types, earlystage granulation tissue was characterized by substantially lower mean gray level and a clearly different histogram. Necrotic tissue had a higher mean gray level, with a virtually normal histogram. In late granulation and early fibrotic tissues, the mean gray level and the histogram could not be discerned from those of normal tendon tissue. The same applied to late fibrotic and scar tissues; mean gray levels were fractionally lower than those of normal tendon tissue with a completely normal histogram.
Conclusions—Although quantification of the transverse ultrasonographic image by use of first-order gray level statistics may be helpful, the method is not sufficiently sensitive to accurately and unequivocally determine the type of tendon tissue. Quantitative analysis should incorporate transverse and longitudinal information. (Am J Vet Res 2000;61: 210–219)
Abstract
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)
Abstract
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)
Abstract
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.
