High-resolution diffusion tensor imaging of the hippocampus in temporal lobe epilepsy.
OBJECTIVE
To assess the quantitative diffusion characteristics of the hippocampus with high-resolution diffusion tensor imaging (DTI) in temporal lobe epilepsy (TLE).


METHODS
Thirteen controls and seven unilateral TLE patients (six with hippocampal sclerosis, one with normal magnetic resonance imaging (MRI)) were scanned with DTI using a zonally magnified oblique multislice echo planar imaging (ZOOM-EPI) acquisition. Fractional anisotropy (FA) and mean diffusivity (MD) were measured in the hippocampi.


RESULTS
The mean hippocampal MD ipsilateral to the seizure focus was higher than the contralateral MD in patients (p<0.05) and the mean MD in controls (p<0.001). Hippocampal FA ipsilateral to the seizure focus was lower than the mean FA in controls (p<0.05). MD asymmetry indexes were significantly different between the patient and control groups (p<0.01). All six individual HS patients had ipsilateral hippocampal MD >or=2 standard deviations (S.D.) above the control mean. The patient with normal structural MRI had bilaterally low hippocampal FA and high MD.


CONCLUSIONS
High-resolution DTI identifies lateralizing abnormalities of MD and FA in TLE patients. This quantitative data on hippocampal integrity may assist in evaluating TLE patients with normal MRI, and in longitudinal studies.
Salmenpera
Tuuli M
TM
The MRI Unit, The National Society for Epilepsy and the Department of Clinical and Experimental Epilepsy, Institute of Neurology, Queen Square, University College London, London WC1N 3BG, UK.
Simister
Robert J
RJ
Bartlett
Philippa
P
Symms
Mark R
MR
Boulby
Philip A
PA
Free
Samantha L
SL
Barker
Gareth J
GJ
Duncan
John S
JS
D000328:Adult; D016880:Anisotropy; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging; D017352:Echo-Planar Imaging / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012598:Sclerosis