Voxel-based diffusion tensor imaging in patients with mesial temporal lobe epilepsy and hippocampal sclerosis.
BACKGROUND
Mesial temporal lobe epilepsy (mTLE) with hippocampus sclerosis (HS) is an important cause for focal epilepsy. In this study, we explored the integrity of connecting networks using diffusion tensor imaging (DTI) and two whole-brain voxel-based methods: statistical parametric mapping (SPM) and tract-based spatial statistics (TBSS).


METHODS
Thirty-three consecutive patients with mTLE and HS undergoing presurgical evaluation were scanned at 3 T, a DTI data set was acquired and parametric maps of fractional anisotropy (FA) and mean diffusivity (MD) were calculated. Twenty-one patients had left hippocampal sclerosis (LHS) and 12 patients had right HS (RHS). These groups were compared to 37 normal control subjects using both SPM5 and TBSS.


RESULTS
The ipsilateral temporal lobe showed widespread FA reduction in both groups. The limbic system was clearly abnormal in the LHS group, also involving the arcuate fasciculus. In RHS, changes were more restricted but also showed involvement of the contralateral temporal and inferior frontal lobe. Increased MD was found in the ipsilateral hippocampus by SPM that was only marginally detected by TBSS. In white matter regions, however, TBSS was more sensitive to changes than SPM.


CONCLUSIONS
DTI detects extensive changes in mTLE with HS. The affected networks were principally in the ipsilateral temporal lobe and the limbic system but also the arcuate fasciculus. SPM and TBSS gave complementary information with higher sensitivity to FA changes using TBSS.
Focke
Niels K
NK
Department of Clinical and Experimental Epilepsy, Institute of Neurology UCL, London WC1N 3BG, UK; National Society for Epilepsy MRI Unit, Chalfont St. Peter, London SL9 0RJ, UK; Department of Clinical Neurophysiology, Georg-August University, 37099 Goettingen, Germany.
Yogarajah
Mahinda
M
Department of Clinical and Experimental Epilepsy, Institute of Neurology UCL, London WC1N 3BG, UK; National Society for Epilepsy MRI Unit, Chalfont St. Peter, London SL9 0RJ, UK.
Bonelli
Silvia B
SB
Department of Clinical and Experimental Epilepsy, Institute of Neurology UCL, London WC1N 3BG, UK; National Society for Epilepsy MRI Unit, Chalfont St. Peter, London SL9 0RJ, UK.
Bartlett
Philippa A
PA
Department of Clinical and Experimental Epilepsy, Institute of Neurology UCL, London WC1N 3BG, UK; National Society for Epilepsy MRI Unit, Chalfont St. Peter, London SL9 0RJ, UK.
Symms
Mark R
MR
Department of Clinical and Experimental Epilepsy, Institute of Neurology UCL, London WC1N 3BG, UK; National Society for Epilepsy MRI Unit, Chalfont St. Peter, London SL9 0RJ, UK.
Duncan
John S
JS
Department of Clinical and Experimental Epilepsy, Institute of Neurology UCL, London WC1N 3BG, UK; National Society for Epilepsy MRI Unit, Chalfont St. Peter, London SL9 0RJ, UK. Electronic address: j.duncan@ion.ucl.ac.uk.
D000293:Adolescent; D000328:Adult; D002648:Child; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012598:Sclerosis