The proximal aspect of the suspensory ligament in the horse: How precise are ultrasonographic measurements?
BACKGROUND
To evaluate intra- and interobserver variability in ultrasonographic measurements of the proximal aspect of the suspensory ligament (PSL) in the horse.


OBJECTIVE
A minimum difference of ≥20% is required to differentiate reliably between physiological and pathological alterations related to dimensions.


METHODS
Two operators examined the PSL in all 4 limbs of 14 horses twice using different techniques and different probes with and without standoff pads. Measurements were taken from the longitudinal and transverse images. Inter- and intraoperator variability was evaluated using agreement indices (AI) and the 95% limits of agreement (LOA).


RESULTS
On the longitudinal scan the mean inter- and intraoperator AIs for dorsopalmar/-plantar thickness were both ≥0.89 and the 95% LOA were within target values for almost all intra- and interoperator comparisons. Similar mean AIs and 95% LOA were calculated for the dorsopalmar/-plantar thickness on the transverse image. For lateromedial width, cross-sectional area and circumference on the transverse scan, the mean inter- and intraoperator AIs ranged between 0.81 and 0.95 and the 95% LOA were higher than target values regardless of the imaging technique used. In general, better values for AIs and 95% LOA were achieved in the fore- compared with the hindlimb.


CONCLUSIONS
Acceptable precision was identified within and between operators only for the dorsopalmar/-plantar thickness in longitudinal and in transverse scanning directions. For the lateromedial width, cross-sectional area and circumference, a relatively large variability was identified. This aspect has to be considered if these parameters are to be used for objective measurement of the PSL from the transverse ultrasound image.
Equine Clinic of the Faculty of Veterinary Medicine, Free University of Berlin, Berlin, Germany. johanna.zauscher@fu-berlin.de
J M
JM
Zauscher
R
R
Estrada
J
J
Edinger
C J
CJ
Lischer
D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000000981:diagnostic imaging*; D006736:Horses; D008022:Ligaments / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D015203:Reproducibility of Results; D013180:Sprains and Strains / Q000000981:diagnostic imaging / Q000662:veterinary*; D014463:Ultrasonography