Assessment of three radiographic projections for detection of fluid in the rabbit tympanic bulla.

Otitis media in the rabbit commonly results in fluid accumulation in the tympanic bulla. Radiographic detection of fluid in the tympanic bulla is only moderately sensitive in the dog and cat. The purpose of this study was to investigate the accuracy of radiographic detection of fluid in the rabbit tympanic bulla for three different radiographic projections. Forty rabbit cadavers were used. Half of the tympanic bullae were randomly allocated to be filled with soft tissue material. Following this procedure, each specimen was radiographed in three projections: dorsoventral (DV), rostro 40 degrees ventral-caudodorsal (R40 degrees V-CdDO), and left and right latero 40 degrees ventral-laterodorsal (Lat40 degrees V-LatDO). After imaging, each specimen was frozen and sectioned to determine the content of the tympanic bullae. Images were interpreted and scored independently by two board-certified radiologists. There was no significant difference in sensitivity or specificity between the three projections when compared with the gross findings following sectioning, but observer confidence was highest for the DV projection. Accuracy of radiographic fluid detection was similar to that reported in the dog and cat. The DV and R40 degrees V-CdDO allow comparison of both tympanic bullae on a single radiograph, but the DV was subjectively easier to position, while the Lat40 degrees V-LatDO requires two radiographs for comparison.