Computed tomography (CT) scan findings in calves with hydranencephaly

Background: Hydranencephaly is unilateral or bilateral loss of cerebral hemispheres and replacement by a CSF-filled sac that is caused by some teratogenic viruses. This disorder can be recognized before death occurs, using CT (Computed Tomography) scan, although pathological findings are useful for confirmation of the diagnosis. Aims: The aim of this study was to determine features of hydranencephaly in calves by Computed Tomography. Methods: In this study CT images were obtained from skulls of 7 same-age calves with neurological signs after slaughter (affected by Akabane virus). To compare the Hounsfield Unit (HU) obtained from each region with the normal brain, a normal calf’s (with the same age) CT images were obtained and HU were measured at the same regions. Then HU was measured in different parts of the affected calves' brain and were compared with the normal calf's brain. Results: CT images of affected calves indicated a hypoattenuated density of cerebral hemispheres and the mean value of HU statistically decreased significantly in these parts of brain compared to the normal calf (P=0.0001). There was no statistically significant difference between the mean value of HU of brain stem of the affected calves and the normal calf (P=0.066). In gross pathology asymmetric fluid-filled sacs, replacing cerebral hemispheres were observed, but the brain stems were intact in all patients. Conclusion: The results showed a strong correlation between CT scan and pathology findings in calves with hydranencephaly. This is the first CT scan-mediated study of calves with hydranencephaly.