Novel approach to magnetic resonance imaging of epileptic dogs — T2 relaxometry of the brain with emphasised hippocampus

Abstract

Hippocampal sclerosis is the most common imaging finding of intractable human epilepsy, and it may play an important role in canine and feline epileptogenesis and seizure semiology, too. The magnetic resonance imaging (MRI) criteria of hippocampal sclerosis are T2 hyperintensity, shrinkage and loss of internal structure. The detection of these changes is often challenging by subjective visual assessment of qualitative magnetic resonance (MR) images. The recognition is more reliable with quantitative MR methods, such as T2 relaxometry. In the present prospective study including 31 dogs with idiopathic epilepsy and 15 control dogs showing no seizure activity, we compared the T2 relaxation times of different brain areas. Furthermore, we studied correlations between the hippocampal T2 values and age, gender and skull formation. We found higher hippocampal T2 values in the epileptic group than in the control; however, these findings were not statistically significant. No correlations were found with age, gender or skull formation. In the individual analysis six epileptic dogs presented higher hippocampal T2 relaxation times than the cut-off value. Two of these dogs were also evaluated as abnormal in the visual assessment. Individual analysis of hippocampal T2 relaxation times may be a helpful method to understand hippocampal involvement in canine epilepsy. Key words: Canine, epilepsy, hippocampus, MRI, T2 relaxometryThe hippocampus, located in the medial temporal lobe of the forebrain belonging to the limbic system, plays an important role in human epilepsy. On one * Corresponding author; E-mail: Borbala.Loerincz@vetmeduni.ac.at; Phone: 0043 (664) 60257-6460; Fax: 0043 (1) This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium for non-commercial purposes, provided the original author and source are credited.

Comparison of electroencephalographic findings with hippocampal magnetic resonance imaging volumetry in dogs with idiopathic epilepsy

“…In those dogs that had radiologically detectable HA with ED from frontal and central leads (35%), HA could have developed secondary to epileptic seizures, with an epileptic focus originating from the frontal lobe and parietal lobe …”

“…It is predicted that HS is related to approximately 80% of all TLE epilepsies in adult humans . According to recent studies, HS, HA, or both play an important role in canine epileptogenesis, and may reflect TLE or mTLE …”

MR relaxometry-based analysis of brain hemorrhages: an experimental study on a rabbit model

“…As far as it concerns Relaxometry applications on animal models, most studies have been performed on rats, mainly on neoplasia [6,19,20]. Further, MRR has been useful in characterizing the hippocampal involvement in epileptic patients [21] and to detect spontaneous brain hemorrhages [22].…”

“…However, most of the animal studies lack an accurate histopathological validation and are typically performed with high field scanners characterized by a high spatial and signal-to-noise-ratio (SNR) [21]. On the one hand, this allows us to achieve a higher spatial resolution and signal-to-noise ratio (SNR).…”

An overview of seizures and epilepsy in rabbits: etiological differences and clinical management

“…This limitation causes frequent administration to maintain adequate serum levels and long term use leads to the development of tolerance to antiseizure activity [31,32]. Phenobarbital is effective as initial therapy and it was determined that it can control the occurrence seizures if serum concentrations are maintained within the target range, 60-80% of dogs with idiopathic epilepsy [33]. Also bromide is effective as add-on therapy when phenobarbital does not provide adequate seizure control [34,35].…”