Comparative magnetic resonance imaging findings between gliomas and presumed cerebrovascular accidents in dogs.

Cerebrovascular accidents, or strokes, and gliomas are common intraaxial brain lesions in dogs. An accurate differentiation of these two lesions is necessary for prognosis and treatment decisions. The magnetic resonance (MR) imaging characteristics of 21 dogs with a presumed cerebrovascular accident and 17 with a glioma were compared. MR imaging findings were reviewed retrospectively by three observers unaware of the final diagnosis. Statistically significant differences between the appearance of gliomas and cerebrovascular accidents were identified based on lesion location, size, mass effect, perilesional edema, and appearance of the apparent diffusion coefficient map. Gliomas were predominantly located in the cerebrum (76%) compared with presumed cerebrovascular accidents that were located mainly in the cerebellum, thalamus, caudate nucleus, midbrain, and brainstem (76%). Gliomas were significantly larger compared with presumed cerebrovascular accidents and more commonly associated with mass effect and perilesional edema. Wedge-shaped lesions were seen only in 19% of presumed cerebrovascular accidents. Between the three observers, 10-47% of the presumed cerebrovascular accidents were misdiagnosed as gliomas, and 0-12% of the gliomas were misdiagnosed as cerebrovascular accidents. Diffusion weighted imaging increased the accuracy of the diagnosis for both lesions. Agreement between observers was moderate (kappa = 0.48, P < 0.01).