Diagnostic imaging of the tympanic bulla and temporomandibular joint in the dog, cat and rabbit

The area of the skull incorporating the tympanic bulla (TB) and temporomandibular joint (TMJ) is significant clinically in the dog, cat, and more recently the rabbit. Diagnostic imaging is important in the assessment of disease of these structures but there is a relative lack of comparative anatomical information relating to the normal that may be used to understand the abnormal features encountered when using currently available diagnostic imaging modalities. A review of conventional radiography demonstrated that views for imaging the canine and feline TB could be extrapolated for use in the rabbit but the same did not apply to the TMJ. Plastinated multiplanar anatomical sections proved useful for the identification of anatomical features on corresponding tomographic images. Ultrasound imaging of this region has not been widely reported but allowed evaluation of the TB in all three species, although the information obtained regarding the TMJ was limited. Directly acquired computed tomography (CT) and Magnetic Resonance (MR) images were of better quality than previous publications due to technological advances in the equipment available. Directly acquired images were still better than reconstructed ones and reduced image acquisition times are likely to make this viable in clincal cases. CT produced optimal imaging of the TB but only allowed assessment of the bony elements of the TMJ. Little information was obtained regarding the normal TB using MR imaging due to the indistinguishable signal voids produced by the bone wall and gas lumen. However, T1 weighted sequences allowed identification of intra-articular TMJ soft tissue structures in the dog and rabbit. While opening the mouth altered the areas of the TMJ examined using each modality, it did not improve visualisation of the intra-articular structures. The introduction of fluid into the middle ear cavity of dog, cat and rabbit cadavers aided identification of the TB and acted as a model of one of the major features of acute otitis media, or inflammation of the middle ear cavity. CT was most accurate at identifying middle ear material in cadavers and clinical cases, while ultrasound produced better results than radiography in cadavers but not clinical cases. These imaging modalities also proved useful in the characterisation of the unexpected anatomical anomalies that were encountered during the study. The results of this study indicate that the optimal imaging technique will vary with the species and area being examined, and that extrapolation between species is not always appropriate. Continual improvements in technology and image quality make studies such as this necessary to allow selection of the most appropriate single or combination of imaging techniques and to obtain the maximum amount of information from the resulting images.EThOS - Electronic Theses Online ServiceGBUnited Kingdo