Abstracts

Rationale: Temporal Lobe Epilepsy is a common and medication resistant form of epilepsy. Patients with TLE sometimes present with no abnormalities at 1.5T MRI. The purpose of this work is to establish a way of identifying abnormalities in those patients at high magnetic field (7 Tesla). High magnetic field MRS facilitates the detection of additional metabolites not readily seen at lower magnetic fields. Using high field ¹H magnetic resonance spectroscopy (MRS) a high quality quantifiable spectra of these patients can be obtained. Metabolites such as Glu, Gln, and Cho are markers for partial epilepsy and can help further localize the seizure origin in the 1.5T negative cases. Methods: The purpose of this pilot study was to investigate the changes in metabolic profile in the hippocampus of MRI negative TLE patients using high magnetic field (7 Tesla) short echo time MRS. Results: Significant differences were observed in metabolite ratios from epileptogenic hippocampus in patients and hippocampus of healthy controls (Figure 1). There was an observed increase in Cho/Cr (p=0.02, two tailed t-test) in patients' epileptogenic hippocampi relative to the contralateral hippocampus. There was a significant increase in Cho/Cr (p=0.03) and Glx/Cr (p=0.05, two tailed t-test) in patients' hippocampi relative to those of controls. Conclusions: These preliminary findings are encouraging and can be useful in the diagnosis of seizure origin in patients where no physical abnormalities are present. The identification of structural and/or metabolic abnormalities not seen with conventional/standard MRI, will allow a better surgical selection of patients with temporal lobe epilepsy who are candidates for surgery. Funding for this project has been supported by the Ontario Brain Institute Epilepsy Discovery Project.