Strain Elastography of Injured Equine Superficial Digital Flexor Tendons: A Reliability Study of Manual Measurements

Early diagnosis of tendon injuries and accurate long-term monitoring of the healing pro-
cess are key for equine veterinarians that use conventional ultrasonography. The development of
strain elastography could improve the management of clinical cases. The aim of the study was to
assess the intraobserver repeatability and interobserver reproducibility of manual measurements of
the colored areas of the tendons within elastograms and to standardize this manual modality by
comparing the analysis of the images with ImageJ. Twenty elastograms of the injured superficial
digital flexor tendons (SDFTs) of horses were analyzed by two different operators after an acute
injury was diagnosed with ultrasonography. Statistical analysis demonstrated excellent intraob-
server repeatability (intraclass correlation coefficient, ICC = 0.949) and good interobserver repro-
ducibility (ICC = 0.855) for manual measurements performed with tools available on the ultrasound
unit. A good agreement between manual measurements and measurements performed with ImageJ
(ICC=0.849) was then demonstrated. Despite its subjectivity, the manual modality proved to be a
valid method for analyzing images obtained with strain elastography.