NMDA-Receptor Activity Visualized with (S)-[N-Methyl-11C]Ketamine and Positron Emission Tomography in Patients with Medial Temporal Lobe Epilepsy
Version of Record online: 2 AUG 2005
Volume 40, Issue 1, pages 30–37, January 1999
How to Cite
Kumlien, E., Hartvig, P., Valind, S., Øye, I., Tedroff, J. and Långström, B. (1999), NMDA-Receptor Activity Visualized with (S)-[N-Methyl-11C]Ketamine and Positron Emission Tomography in Patients with Medial Temporal Lobe Epilepsy. Epilepsia, 40: 30–37. doi: 10.1111/j.1528-1157.1999.tb01985.x
- Issue online: 2 AUG 2005
- Version of Record online: 2 AUG 2005
- Accepted July 27, 1998.
- Medial temporal lobe epilepsy;
- NMDA-receptor channel;
- Positron emission tomography
Summary: Purpose: To determine whether neurochemical activation of the N-methyl-D-aspartate (NMDA) receptor-gated ion channel shows quantitative changes, measured as binding of 11C-labeled (S)-[N-methyl]ketamine, in patients with medial temporal lobe epilepsy (MTLE).
Methods: Eight patients with MTLE who were evaluated regarding epilepsy surgery underwent positron emission tomography (PET) with (S)-[N-methyl-11C]ketamine. The presurgical investigations included magnetic resonance imaging (MR1), PET with 18F-fluoro-deoxyglucose (18FDG), and seizure monitoring by using video-EEG. The uptake of (S)-[N-methyl-11C]ketamine in the temporal lobe of ictal onset was compared with the contralateral side and correlated to changes in regional glucose metabolism measured by PET with 18FDG.
Results: (S)-[N-methyl-11C]ketamine rapidly reached the brain, and high radioactivities were measured in the striatum, thalamic nuclei, and cortical regions. Overall the brain uptake and regional binding potentials of (S)-[N-methyl-11C]ketamine were similar to measurements observed previously in healthy controls. However, 20 min after administration, when blood flow influence was negligible, a side-to-side comparison revealed a 9–34% reduction of tracer radioactivity in the temporal lobes of ictal onset. At earlier times, the differences in binding potentials were less pronounced, 9–21%. The magnitude and distribution of the reduction were similar to the metabolic pattern seen on PET scans with 18FDG.
Conclusions: Radioactivity uptake of intravenously administered (S)-[N-methy]-11C]ketamine was reduced in temporal lobes of ictal in patients with TLE. This may reflect reduced NMDA-receptor density, reduced perfusion, focal atrophy, or other factors.