TABLE 1

Targeted Pathways, Used Radiotracers, and Their Usual Uptake Pattern in Epileptogenic Region

TargetUsed radiotracersUptake pattern in epileptogenic region
Blood perfusion15O-H2O, 99mTc-ethyl cysteinate dimer, 99mTc-hexamethyl propyleneamine oximeInterictal decrease; ictal increase
Metabolic pathways
 Glucose metabolism18F-FDGInterictal decrease*; ictal increase
 Serotonin/kynurenine metabolism11C-α-methyl-l-tryptophanInterictal increase
 Dopamine synthesis18F-l-DOPA†Interictal decrease
 Monoamine oxidase11C-deuterium-deprenyl‡Interictal increase
Receptors
 Benzodiazepine11C-flumazenil§
 Opiate11C-carfentanil∥, 18F-cyclofoxy, 11C-diprenorphine#, 11C-methylnaltrindole**Interictal increase; interictal decrease
 5-hydroxytryptamine18F-FCWAY††, 11C-WAY††, 18F-MPPF††Interictal decrease
 Dopamine18F-fallypride‡‡, 11C-SCH23390§§Interictal decrease
 Peripheral benzodiazepine or translocator protein11C-PK11195∥∥, 11C-PBR28∥∥Interictal increase
 Histamine11C-doxepin¶¶Interictal increase
 N-methyl-d-aspartic acid11C-ketamine##Interictal decrease
 Acetylcholine18F-FA85380***Interictal decrease

  • FCWAY = trans-4-fluoro-N-2-[4-(2-methoxyphenyl) piperazin-1-yl] ethyl-N-(2-pyridyl) cyclohexanecarboxamide; MPPF = 4-18F-fluoro-N-(2-[4-(2-methoxyphenyl)-l-piperazinyl]ethyl)-N-(2-pyridinyl)benzamide; l-DOPA = l-3,4-dihydroxyphenylalanine (levodopa); PK11195 = 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide; PBR28 = N-acetyl-N-(2-[11C-methoxybenzyl)-2-phenoxy-5-pyridinamine.

  • ↵* Can show increased uptake if continuous spiking (interictal) or epileptiform discharges (ictal).

  • ↵† Acts on dopamine receptors.

  • ↵‡ Monoamine oxidase-B inhibitor.

  • ↵§ γ-aminobutyric acid A benzodiazepine receptor.

  • ↵∥ μ-receptor agonist.

  • ↵ μ and κ antagonist.

  • ↵# μ-, δ- and κ-receptor antagonist.

  • ↵** δ-receptor antagonist.

  • ↵†† 5HT1A antagonist.

  • ↵‡‡ D2/D3 antagonist.

  • ↵§§ D1 antagonist.

  • ↵∥∥ Peripheral benzodiazepine receptor or translocator protein antagonist.

  • ↵¶¶ 1H receptor antagonist.

  • #NMDA antagonist.

  • ↵*** α4/β2 nAChR agonist.