RELATIVE UTILITY OF H-1 SPECTROSCOPIC IMAGING AND HIPPOCAMPAL VOLUMETRY IN THE LATERALIZATION OF MESIAL TEMPORAL-LOBE EPILEPSY

Objectives: To determine the relative utility of H-1 MRSI and hippocam pal volumetry for the lateralization of mesial temporal lobe epilepsy (MTLE) in patients with intractable epilepsy. Background: MTLE is the most common partial-onset seizure disorder in patients undergoing temp oral lobe epilepsy surgery. MR volumetry and spectroscopy are reliable preoperative imaging techniques for the lateralization of MTLE, Metho ds: We analyzed the H-1 MRSI and hippocampal formation volumes preoper atively in 30 consecutive patients who had undergone temporal lobectom y. Results: Volumetry correctly lateralized the side of surgery in 93% of patients and H-1 MRSI did so in 97% of patients. Incorrect lateral ization occurred by volumetry in two patients and by H-1 MRSI in one p atient. Concordance between all MRI modalities was 73%. Pearson's anal ysis revealed no correlation between the degree of hippocampal volume loss and the creatine-to-N-acetylated-compounds ratio. Conclusions: Vo lumetry and H-1 MRSI correctly lateralized most patients with MTLE and complement each other in final lateralization. The lack of correlatio n between the severity of volume loss and the degree of metabolic dist urbance suggests that the techniques examine distinct pathophysiologic processes in MTLE.