Tonight’s session was all about cross-sectional imaging. CT and MR are becoming more and more in demand in the world of veterinary radiology. They provide valuable diagnostic informtion in complex and inaccessible areas such as the nose and the brain.
One of the cases was an MR of a 1.5 year old Chihuahua with central vestibular signs. There was a lesion in the left hemisphere of the cerebellum, which was hypointense on T1, hyperintense on T2, and ring-enhancing after gadolinium. There was also a large amount of edema surrounding the lesion on T2-weighted images.
Differential diagnoses included abscess and glioma. On post mortem, the lesion turned out to be histiocytic encephalitis with necrosis, and no organisms were found.
This was a good lesson in keeping differential diagnoses broad, then working down to specifics. The ring enhancement, and fluid containing nature of the lesion along with the history and signalment indicated an inflammatory lesion which could be infectious or non-infectious. Infectious causes could be bacterial encephalitis, and non-infectious necrosis such as GME or necrotizing encaphalitis are other possibilities. This lesion turned out to be sterile, so “abscess” was an incorrect diagnosis. The DAMNIT scheme can help you to work from more broad categories of disease down to the more specific without forgetting anything.
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