[11 C]Flumazenil binding in the medial temporal lobe in patients with temporal lobe epilepsy: correlation with hippocampal MR volumetry, T2 relaxometry, and neuropathology.
OBJECTIVE
To detect reduced [11C]flumazenil in patients with temporal lobe epilepsy (TLE) and to relate binding to histopathology.


METHODS
The authors studied 16 patients who underwent epilepsy surgery because of drug-resistant TLE using [11C]flumazenil PET and quantitative MRI. In 12 patients, resected hippocampus was available for histologic analysis. [11C]Flumazenil binding potential (fitted BP) was assessed with the simplified reference tissue model.


RESULTS
[11C]Flumazenil fitted BP in the medial temporal lobe was reduced in all patients with abnormal hippocampal volumetry or T2 relaxometry on MRI. Fitted BP was also reduced in 46% of the patients with hippocampal volume within the normal range and in 38% of patients with less than 2 SD T2 prolongation. In all MRI-negative/PET-positive patients, the histologic analysis verified hippocampal damage. Also, [11C]flumazenil fitted BP correlated with the severity of reduced hippocampal volume, T2 prolongation, and histologically assessed neuronal loss and astrogliosis.


CONCLUSIONS
[11C]Flumazenil PET provides a useful tool for investigating the hippocampal damage in vivo even in patients with no remarkable hippocampal abnormalities on quantitative MRI.
Lamusuo
S
S
Department of Neurology, University of Turku, Finland.
Pitkänen
A
A
Jutila
L
L
Ylinen
A
A
Partanen
K
K
Kälviäinen
R
R
Ruottinen
H M
HM
Oikonen
V
V
Någren
K
K
Lehikoinen
P
P
Vapalahti
M
M
Vainio
P
P
Rinne
J O
JO
D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000627:therapeutic use; D001569:Benzodiazepines / Q000627:therapeutic use; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000628:therapy; D005260:Female; D005442:Flumazenil / Q000493:pharmacokinetics*; D018757:GABA Modulators / Q000493:pharmacokinetics; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome; D014635:Valproic Acid / Q000627:therapeutic use; D020888:Vigabatrin / Q000627:therapeutic use
D000927:Anticonvulsants; D018757:GABA Modulators; D001569:Benzodiazepines; D005442:Flumazenil; D014635:Valproic Acid; D020888:Vigabatrin