Cross-Modality Diagnostic Agreement in Canine Medial Coronoid Disease in a Screening Population: Radiographs vs. CT in 424 Elbow Joints

Diagnostic imaging is a crucial non-invasive tool for evaluating canine elbow joints, particularly for screening and treatment planning of medial coronoid disease (MCD). Radiography remains the most accessible and widely used screening modality, but its diagnostic accuracy varies significantly. Sensitivity values reported in previous studies vary depending on factors such as study population, imaging technique, and interpretation criteria. This study compared four measures (sensitivity, specificity, positive and negative predictive value) of radiography with a more advanced imaging method, computed tomography (CT), which provides more detailed images of bones. The results showed that radiography correctly identified 65% of the cases (17/26), while missing some of the affected joints. Furthermore, 7% of the healthy joints (29/398) were misdiagnosed as diseased, leading to a specificity of 93% (369/398). For a disease prevalence of 6% (26/424), the positive and negative predictive value of radiography were 37% (17/46) and 98% (369/378), respectively. Overall, when CT is available, it is the preferred technique for screening. In cases where it is not available, it is important to have an idea of the sensitivity and specificity, but also of the positive and negative predictive value, especially at low prevalences. These results help veterinarians make better decisions when screening for elbow problems in dogs.