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Published on: September 12, 2011
Study of the microstructure of brain white matter in medial temporal lobe epilepsy based on diffusion tensor imaging
Yiwei Zhang1,2, Zhaoxi Liu2, Wanchen Dou3
1Department of Radiology, Peking University First Hospital, Beijing, China.
Objectives:
To compare the white matter (WM) asymmetry in left and right medial temporal lobe epilepsy (mTLE) with and without hippocampal sclerosis (HS+, HS-) and assess the correlation of preoperative asymmetry and the dynamics of WM fibers with surgical outcomes.
Materials And Methods:
Preoperative MRI scans were collected from 58 mTLE patients (40 HS+, 18 HS-); 15 (11 HS+, 4 HS-) then underwent postoperative MRI scans. DTI parameters, including the fractional anisotropy (FA), mean diffusion coefficient (MD), axial diffusion coefficient (AD), and radial diffusion coefficient (RD), were extracted from 20 paired WM tracts by PANDA based on the JHU WM tractography atlas. The bilateral cerebral parameters and the pre- to postoperative changes in the DTI parameters of specific fiber tracts were compared. The asymmetry indexes (AIs) of paired fibers were also analyzed.
Results:
There were fewer asymmetrical WM fibers in HS- patients than in HS+ patients. The pattern of WM asymmetry differed between left and right mTLE patients. Differences in the FA AI of the inferior fronto-occipital fasciculus and inferior longitudinal fasciculus (ILF) were found in left HS+ patients with different surgical outcomes. All mTLE patients exhibited decreases in FA and increases in MD and RD in specific ipsilateral WM fibers. In International League Against Epilepsy (ILAE) grade 1 patients, the MD values in the ipsilateral CGH increased over time, whereas the RD values in the ipsilateral ILF and the AD values in the ipsilateral ILF and UNC decreased. In ILAE grade 2-5 patients, the FA values in the ipsilateral cingulate gyrus part of the cingulum (CGC) increased over time.
Conclusion:
The WM tract asymmetry was more extensive in HS+ patients than in HS- patients. The preoperative WM fiber AIs in left HS+ patients may be useful for surgical prognosis. Additionally, pre- to postoperative changes in WM fibers may help predict surgical outcomes.
Insights
White matter (WM) asymmetry is more pronounced in medial temporal lobe epilepsy (mTLE) with hippocampal sclerosis (HS+). Preoperative WM fiber asymmetry and changes after surgery can help predict surgical outcomes in mTLE patients.
Area of Science:
- Neuroimaging
- Epilepsy Research
- White Matter Integrity
Background:
- Medial temporal lobe epilepsy (mTLE) is often associated with white matter (WM) abnormalities.
- Hippocampal sclerosis (HS) is a common finding in mTLE, potentially influencing WM structure.
- Understanding WM asymmetry and its relationship to surgical outcomes is crucial for patient management.
Purpose of the Study:
- To compare white matter (WM) asymmetry in left and right mTLE patients with and without hippocampal sclerosis (HS+ and HS-).
- To assess the correlation between preoperative WM asymmetry, WM fiber dynamics, and surgical outcomes.
- To investigate the predictive value of WM changes for surgical success in mTLE.
Main Methods:
- Collected preoperative MRI scans from 58 mTLE patients (40 HS+, 18 HS-).
- Utilized diffusion tensor imaging (DTI) parameters (FA, MD, AD, RD) extracted from 20 WM tracts using PANDA software.
- Analyzed asymmetry indexes (AIs) and pre- to postoperative changes in DTI parameters for specific fiber tracts.
Main Results:
- WM asymmetry was more extensive in HS+ patients compared to HS- patients.
- Distinct patterns of WM asymmetry were observed between left and right mTLE.
- Decreases in FA and increases in MD/RD were noted in ipsilateral WM fibers across all mTLE patients post-surgery.
- Specific changes in FA, MD, and RD in tracts like the inferior longitudinal fasciculus (ILF) and cingulate gyrus part of the cingulum (CGC) correlated with surgical outcomes (ILAE grades).
Conclusions:
- WM tract asymmetry is more prevalent in mTLE patients with hippocampal sclerosis.
- Preoperative WM fiber asymmetry in left mTLE with HS+ may serve as a prognostic indicator.
- Monitoring pre- to postoperative changes in WM fibers can aid in predicting surgical outcomes for mTLE patients.
