The Magnetic Resonance Imaging Appearance of Canine Intra-Axial Primary Brain Tumors Relates More Strongly to Tumor Grade Than Tumor Type
Conference Proceedings, (2012). American College of Veterinary Internal Medicine, New Orleans: p.423
The association between magnetic resonance imaging (MRI) features of canine intra-axial primary brain tumors and histopathological type and grade was determined. Fifty six dogs with brain lesions were studied, including 34 cases of grade 2 to 4 tumors (17 astrocytomas, 14 oligodendrogliomas, 3 primitive neuroectodermal tumors) and 22 distractors. All 56 brain lesions had complete brain MRI and histopathological diagnosis. Five investigators blinded to the histopathologic diagnosis independently evaluated 22 radiological features according to a standardized grading system. Contingency tables were analyzed using Fishers exact test; p<0.05 was considered significant. The severity of contrast enhancement was associated with increasing tumor grade, being more severe in the highest grade (p=0.0046), and less in grade 2 tumors (p=0.001). Grade 4 tumors more commonly exhibited a spherical-ovoid shape (p=0.030) and an isointense or hyperintense T1 signal (p=0.038). Gradient echo signal voids (p=0.0007), a single cyst (p=0.0013), and multiple intra-tumoral fluid accumulations (p=0.046) were more common in grade 3 and 4 tumors. Grade 2 tumors occurred more commonly in a diencephalic location (p=0.023), caused midline-shift or falcine herniation (p=0.012) and impinged on adjacent ventricles (p=0.0017). Astrocytomas more often had a caudal fossa location (p=0.024) than oligodendrogliomas, while oligodendrogliomas more commonly distorted adjacent ventricles (p=0.0068), caused caudal cerebellar herniation (p=0.011) and exhibited T1 hypointensity (p=0.0064); primitive neuroectodermal tumors were excluded from the analysis of tumor type due to low case numbers. The MRI appearance of canine intra-axial primary brain tumors is significantly related to tumor grade, whereas differences associated with tumor type are less characteristic.