Comparison of conventional radiography and computed tomography as aids in the diagnosis of osteomyelitis in 11 foals.

Abstract: Conventional radiography is currently the most common imaging modality used by veterinarians investigating foals with suspected osteomyelitis. Emerging evidence in adult horses and humans suggests computed tomography (CT) is a superior modality for evaluation of osseous changes in general. This study aimed to evaluate the potential benefits of CT versus conventional radiography in cases of osteomyelitis in foals. Methods: Cases of osteomyelitis in foals under 6 months of age admitted over a 6-year period at a single referral hospital that had both CT and conventional radiography images were retrieved. Case details and measurements of the largest area of bone lysis identified in two planes (lateromedial/sagittal and dorsopalmar/dorsal) were evaluated by three veterinarians with a range of experience. Results: A significant difference regarding lesion size was seen on the lateromedial (LM) radiographic projections compared with the equivalent sagittal plane CT image. The LM radiographic evaluation resulted in a 37% underestimation of the area of the lesion. Additionally, use of the LM radiographic projections were 2.5-fold more variable in the measurement area compared with CT. In general, regardless of projection, CT produced more information regarding lesion area and, in some cases, detected osseous changes that were not evident on the radiographs. Conclusions: LM radiographic projections are less reliable and commonly result in an under-appreciation of lesion size and extent. CT detected lesions that were difficult or impossible to identify on radiographs and may allow improved treatment planning.