Relative utility of 1H spectroscopic imaging and hippocampal volumetry in the lateralization of mesial temporal lobe epilepsy

Objectives: To determine the relative utility of H-1 MRSI and hippocampal 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 temporal lobe epilepsy surgery. MR volumetry and spectroscopy are reliable preoperative imaging techniques for the lateralization of MTLE, Methods: We analyzed the H-1 MRSI and hippocampal formation volumes preoperatively in 30 consecutive patients who had undergone temporal lobectomy. Results: Volumetry correctly lateralized the side of surgery in 93% of patients and H-1 MRSI did so in 97% of patients. Incorrect lateralization occurred by volumetry in two patients and by H-1 MRSI in one patient. Concordance between all MRI modalities was 73%. Pearson's analysis revealed no correlation between the degree of hippocampal volume loss and the creatine-to-N-acetylated-compounds ratio. Conclusions: Volumetry and H-1 MRSI correctly lateralized most patients with MTLE and complement each other in final lateralization. The lack of correlation between the severity of volume loss and the degree of metabolic disturbance suggests that the techniques examine distinct pathophysiologic processes in MTLE.