"Magnetic resonance imaging negative positron emission tomography positive" temporal lobe epilepsy: FDG-PET pattern differs from mesial temporal lobe epilepsy.
OBJECTIVE
Some patients with temporal lobe epilepsy (TLE) lack evidence of hippocampal sclerosis (HS) on MRI (HS-ve). We hypothesized that this group would have a different pattern of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET) hypometabolism than typical mesial TLE/HS patients with evidence of hippocampal atrophy on magnetic resonance imaging (MRI) (HS+ve), with a lateral temporal neocortical rather than mesial focus.


METHODS
Thirty consecutive HS-ve patients and 30 age- and sex-matched HS+ve patients with well-lateralized EEG were identified. FDG-PET was performed on 28 HS-ve patients and 24 HS+ve patients. Both groups were compared using statistical parametric mapping (SPM), directly and with FDG-PET from 20 healthy controls.


RESULTS
Both groups showed lateralized temporal hypometabolism compared to controls. In HS+ve, this was antero-infero-mesial (T = 17.13); in HS-ve the main clustering was inferolateral (T = 17.63). When directly compared, HS+ve had greater hypometabolism inmesial temporal/hippocampal regions (T = 4.86); HS-ve had greater inferolateral temporal hypometabolism (T = 4.18).


CONCLUSIONS
These data support the hypothesis that focal hypometabolism involves primarily lateal neocortical rather than mesial temporal structures in 'MRI-negative PET-positive TLE.'
Carne
R P
RP
Victorian Epilepsy Centre, St. Vincent's Hospital, Melbourne, Victoria, Australia. carnero@svhm.org.au
Cook
M J
MJ
MacGregor
L R
LR
Kilpatrick
C J
CJ
Hicks
R J
RJ
O'Brien
T J
TJ
D000328:Adult; D016022:Case-Control Studies; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D011859:Radiography; D012598:Sclerosis