Abstracts

Rationale: Magnetic resonance spectroscopy (MRS) allows the in vivo assessment of macromolecules involved in neuronal process, for example, neurotransmitters. Some important differences between MRS and magnetic resonance imaging (MRI) arise from the fact that the primary aim of MRS is to obtain chemical information and that of MRI is to provide spatial information. The temporal lobe epilepsy (TLE) is associated with hippocampal atrophy. Usually MRS is used to help in lateralization of epileptogenic foci, but in this study we used this Magnetic Resonance technique to test the hypothesis that neuronal loss occur also in other parts of brain. Methods: 27 patients with clinical diagnosis of Temporal Lobe Epilepsy and 24 healthy volunteers were evaluated. The two groups were matched in age. Images were acquired using a 3 T MR scanner (Achieva, Philips Medical Systems) with a SENSE 8-channel head coil during a single MR imaging session. The spectroscopy data were acquired with a PRESS sequence type (from the English point resolved spectroscopy sequence) in the axial plane with echo time (TE) of 288 ms and repetition time (TR) of 2000. The size of the volume of interest was 80x60x20 mm, positioned on the cingulate gyrus, corpus callosum and surrounding white matter, a region considered as representative of the whole brain. Metabolic concentrations were measured at 2.0 ppm (NAA), 3.0 ppm (Cre) and 3.2 ppm (Cho). Metabolites were assessed as ratios to Cr [NAA/Cr, Cho/ Cr] and in absolute units. Results: The index NAA/Cre showed a significant difference (p=0,035) between patients (3,42 0,66) and healthy controls (3,02 0,63). But the index Cho/ Cr wasn t significant (p=0,326). Conclusions: In our patients group, the region of interesting was characterized by a decrease in the NAA concentration, this indicate neuronal dysfunction. These results are consistent with the hypothesis that exist neuronal loss outside the temporal lobe region.