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Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
Side matters: diffusion tensor imaging tractography in left and right temporal lobe epilepsy.
M E Ahmadi1, D J Hagler, C R McDonald
1Multimodal Imaging Laboratory, University of California, San Diego, CA 92103-8756, USA. mazyar.ahmadi@gmail.com
AJNR. American Journal of Neuroradiology
|June 11, 2009
Summary
Diffusion tensor imaging (DTI) tractography reveals widespread white matter changes in temporal lobe epilepsy (TLE). These changes, particularly reduced fractional anisotropy (FA), help lateralize the seizure focus, even without visible hippocampal abnormalities.
Area of Science:
- Neuroimaging
- Epileptology
- Diffusion Tensor Imaging
Background:
- Noninvasive imaging is crucial for seizure focus lateralization in presurgical temporal lobe epilepsy (TLE) patients.
- Diffusion tensor imaging (DTI) tractography offers potential for evaluating white matter integrity in TLE.
Purpose of the Study:
- To assess the utility of DTI tractography in lateralizing the seizure focus in patients with TLE.
- To compare white matter fiber tract fractional anisotropy (FA) between TLE patients and controls.
Main Methods:
- 21 TLE patients and 21 controls underwent 1.5T MRI with 51 diffusion-gradient-direction images.
- Eight pairs of white matter fiber tracts were traced, and fractional anisotropy (FA) was calculated.
- Fiber tract FA asymmetry and discriminant function analysis were performed.
Main Results:
- TLE patients showed decreased FA in ipsilateral fiber tracts compared to controls.
- Left TLE patients exhibited more widespread ipsilateral and contralateral FA reductions than right TLE patients.
- Discriminant function analysis accurately lateralized TLE in 90% of cases, particularly using uncinate fasciculus and parahippocampal tracts.
Conclusions:
- Widespread reductions in fiber tract FA are characteristic of TLE, most pronounced ipsilateral to the seizure focus.
- DTI tractography effectively lateralizes the seizure focus in TLE, independent of hippocampal pathology visible on conventional MRI.
- Left TLE presents with more diffuse white matter changes compared to the primarily ipsilateral changes in right TLE.
