a) MRS in Children with TLE: High resolution MRI allows to identify mesial temporal sclerosis (MTS), a frequent cause of complex partial seizures in most situations. However, TLE starts in early childhood and MTS gradually develops over months to years, first passing through stages of gliotic changes of the hippocampal region, until the typical imaging patterns appear in late childhood and adolescence. Moreover, recurrent seizure attacks are further damaging the mesial temporal structures, predominantly amygdala and hippocampus. Surgical removal of the seizure focus is often the only curative remedy after antiepileptic drug therapy is unsuccessful. Proton MRS should allow to detect early metabolic alterations before structural changes occur in the TL.

In this project, we have examined children of different ages that present with TLE using MRI and single voxel proton MRS and Chemical Shift Imaging comparing them to an age matched control group. After taking spectra from either side of the anterior part of the TL and calculating a metabolic quotient of N-acetyl aspartate, choline and creatine, a lateralisation index (LI) is determined that allowed to identify metabolic asymmetry. The amount of metabolic asymmetry is correlated with information from high resolution MRI and EEG findings.

b) Quantification of Glutamine/Glutamate and GABA using Multiecho MRS (CPRESS): The glutamate and GABA play an important role in many neurological diseases, e.g. in epilepsy. Monitoring GABA during epilepsy therapy can be of great clinical importance. A new sequence (CPRESS = Carr-Pursell-selected PointRESolved Spectroscopy) was developed, which allows to prepare the spin-ensemble of the coupled spins before data acquisition. This results in a significant improvement of signal intensity of overlapping multiplets in the spectra of substances like glutamate and GABA due to J-coupling. First measurements of GABA in infants under Vigabatrin therapy were successful.

T. Thiel, C. Panow, J. Hennig, E. Martin. Metabolic Asymmetries as an Early Indicator for Temporal Lobe Epilepsy in Children: A Comparison with EEG and High Resolution MRI. ISMRM Seventh Scientific Meeting, Philadelphia, May 1999, p. 1473.