Multisection proton MR spectroscopy for mesial temporal lobe epilepsy.
OBJECTIVE
Extensive metabolic impairments have been reported in association with mesial temporal lobe epilepsy (mTLE). We investigated whether proton MR spectroscopy ((1)H-MRS) depicts metabolic changes beyond the hippocampus in cases of mTLE and whether these changes help lateralize the seizure focus.


METHODS
MR imaging and (1)H-MRS were performed in 15 patients with mTLE with a postoperative diagnosis of mesial temporal sclerosis and in 12 control volunteers. Point-resolved spectroscopy and multisection (1)H-MRS measured N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the hippocampus, temporal opercular and lateral cortices, insula and cerebellum, and frontal, parietal, and occipital lobes. Metabolites were assessed as ratios to Cr and in absolute units.


RESULTS
Twelve patients had ipsilateral hippocampal atrophy; three had negative imaging results. In the ipsilateral hippocampus, absolute NAA (/NAA/) was 27.3% lower in patients compared with that in control volunteers (P <.001) and 18.5% lower compared with that in the contralateral side (P <.01). /NAA/ averaged over selected regions in the ipsilateral temporal lobes of patients with mTLE was 19.3% lower compared with the mean in the control group (P <.0001) and by 17.7% lower compared with the contralateral values (P <.00001). Using only hippocampal data, 60% of the cases of mTLE were correctly lateralized. Lateralization, determined using whole temporal lobe data, had 87% sensitivity and 92% specificity. /NAA/ was bilaterally reduced in the frontal, parietal, and occipital lobes of patients with mTLE compared with that in control volunteers (P <.01).


CONCLUSIONS
Multisection (1)H-MRS depicts interictal reductions of NAA in the ipsilateral temporal lobe beyond the hippocampus and accurately lateralizes seizure foci.
Capizzano
Arístides A
AA
Department of Veterans Affairs Medical Center, Magnetic Resonance Spectroscopy Unit, University of California, San Francisco, USA.
Vermathen
Peter
P
Laxer
Kenneth D
KD
Matson
Gerald B
GB
Maudsley
Andrew A
AA
Soher
Brian J
BJ
Schuff
Norbert W
NW
Weiner
Michael W
MW
D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D016022:Case-Control Studies; D002794:Choline / Q000378:metabolism*; D003401:Creatine / Q000378:metabolism*; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism*; D005260:Female; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline