Grading of oligodendroglioma in dogs based on magnetic resonance imaging.

Moderate-to-marked CE and ring pattern were present in dogs with OG III but not in OG II. The presence of cystic structures, GRE signal voids, and necrosis was strongly associated with OG III. Although the importance of brain tumor grading in dogs with regard to prognosis and treatment options remains unknown, the results indicate that MRI reflects the histological features used for grading OG in dogs.