Longitudinal volumetric assessment of ventricle enlargement in dogs trained for functional magnetic resonance imaging (fMRI) studies

Abstract

Recent studies suggest that clinically sound ventriculomegaly in dogs could be a preliminary or an arrested form of the clinically significant hydrocephalus. There are only a few longitudinal studies measuring ventricular volume changes over time, but assessment of cognitive abilities associated with the change has not been completed. Frontal lobe deficits, such as attention and inhibition have been shown to be the earliest signs of hydrocephalus in humans. We evaluated changes of ventricular volumes over time in fMRI trained dogs. Staying completely motionless in the MR scanner while awake, entails at least two important cognitive skills; attention and inhibition. Our research question was whether ventricular enlargement developing over time has any effect on canine cognitive ability. Seven healthy dogs 2-8 years old at the baseline scan and 4 years older at rescan participated in a rigorous and gradual training for staying motionless (< 1 mm) in the MR scanner without any sedation during a 6 minute-long structural MR sequence. On T1 structural images, volumetric analyses of the lateral ventricles were completed by software guided semi-automated tissue type segmentation.