Development of a Morphometric Magnetic Resonance Image Parameter Suitable for Distinguishing Between Normal Dogs and Dogs With Cerebellar Atrophy

Abstract

Neurodegenerative diseases affect the cerebellum of numerous dog breeds. Although subjective, magnetic resonance (MR) imaging has been used to detect cerebellar atrophy in these diseases, but there are few data available on the normal size range of the cerebellum relative to other brain regions. The purpose of this study was to determine whether the size of the cerebellum maintains a consistent ratio with other brain regions in different ages and breeds of normal dogs and to define a measurement that can be used to identify cerebellar atrophy on MR images. Images from 52 normal and 13 dogs with cerebellar degenerative diseases were obtained. Volume and mid-sagittal cross-sectional area of the forebrain, brainstem, and cerebellum were calculated for each normal dog and compared between different breeds and ages as absolute and relative values. The ratio of the cerebellum to total brain and of the brainstem to cerebellum mid-sagittal cross-sectional area was compared between normal and affected dogs and the sensitivity and specificity of these ratios at distinguishing normal from affected dogs was calculated. The percentage of the brain occupied by the cerebellum in diverse dog breeds between 1 and 5 years of age was not significantly different, and cerebellar size did not change with increasing age. Using a cut off of 89%, the ratio between the brainstem and cerebellum mid-sagittal cross-sectional area could be used successfully to differentiate affected from unaffected dogs with a sensitivity and specificity of 100%, making this ratio an effective tool for identifying cerebellar atrophy on MR images. r

Genome sequencing reveals a splice donor site mutation in the SNX14 gene associated with a novel cerebellar cortical degeneration in the Hungarian Vizsla dog breed

“…1), similar to previous MRI reports [5, 16, 25, 26]. The MRI scan performed in this HV with CCD revealed a mid-sagittal cross-sectional brainstem to cerebellar area ratio of 81.1 %, a value lower than a previously reported lower limit of 89 % for the diagnosis of cerebellar atrophy using MRI [25]. However, the 13 dogs used in that MRI study consisted mainly of breeds with an adult onset, slowly progressive form of CCD.…”

“…1). The gross size of the cerebellum otherwise appeared largely normal, with a mid-sagittal cross-sectional brainstem to cerebellar area ratio of 81.1 % [25]. There were also mildly enlarged cerebral sulci and lateral ventricles, with the rest of the brain MRI otherwise unremarkable.…”

“…The HV in the current study also underwent MRI early in the disease, and therefore given the variability in the time point in the disease course at which MRI is performed, comparison with dogs in the previous study is difficult. Given the uncertainty regarding the length of time required for cerebellar atrophy to be detectable on MRI in cases of CCD [25], it is possible that MRI was performed in Case 1 before sufficient atrophy to cause a reduction in MRI area ratio had developed.…”

Canine Hereditary Ataxia

“…However, neurodegenerative processes can result in brain atrophy and dogs that have hereditary ataxia frequently exhibit atrophy of the cerebellum on MRI images. 10 Sagittal T2-weighted images are especially useful because they highlight the increase in CSF volume around the atrophied cerebellar folia (Fig. 1).…”

“…A ratio of the brainstem to cerebellar cross-sectional area of greater than 89% had 100% sensitivity and specificity for detecting affected individuals. 10 The sensitivity in detecting other forms of hereditary ataxia is unknown.…”