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Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
Mean apparent propagator-MRI: A new diffusion model which improves temporal lobe epilepsy lateralization
Keran Ma1, Xiaonan Zhang1, Huiting Zhang2
1Department of Magnetic Resonance Imaging, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, China.
Purpose:
To compare MRI volume measurements, FLAIR image intensity, Diffusion tensor imaging (DTI) and mean apparent propagator (MAP)-MRI measurements in hippocampus ipsilateral and contralateral to the epileptogenic focus for non-invasive lateralization of temporal lobe epilepsy (TLE) and also compare these DTI and MAP-MRI measurements to cognitive function.
Method:
A cohort of patients with unilateral TLE and aged-and gendered-matched controls were enrolled in this retrospective study. T1-weighted MPRAGE data for the volume, FLAIR image intensity, DTI and MAP-MRI parameters were performed for bilateral hippocampi of all subjects. The sensitivity, specificity, lateralization ratios and Cohen's d effect sizes of all MR measurements were calculated. Pearson correlation analysis was performed to compare DTI and MAP-MRI measurements to cognitive function.
Results:
We evaluated 23 patients and 17 controls. The MAP-MRI parameter 'return to the plane probability' (RTPP) had the strongest effect size (d = -1.678, lateralization ratio = 86.36 %) for differentiating hippocampus ipsilateral to the epileptogenic focus from contralateral hippocampus when compared to all other DTI/MAP-MRI parameters, signal intensity on FLAIR and hippocampal volumes. Mean diffusivity (MD), radial diffusivity (RD), mean square displacement (MSD) were each negatively correlated to clinical measures of delayed recall (r = -0.758; r = -0.772; r = -0.684, respectively). While return to the axis probability (RTAP) return to the origin probability (RTOP) and fractional anisotropy (FA) were positively correlated (r = 0.832; r = 0.813; r = 0.717, respectively) (all P < 0.05).
Conclusion:
MAP-MRI measurements are promising radiologic biomarkers for the non-invasive lateralization of epileptogenic foci in TLE.
Insights
Mean Apparent Propagator MRI (MAP-MRI) shows promise for non-invasively lateralizing temporal lobe epilepsy (TLE) foci. Specific MAP-MRI measures strongly differentiate affected hippocampi and correlate with cognitive function.
Area of Science:
- Neuroimaging
- Epilepsy Research
- Radiology
Background:
- Temporal lobe epilepsy (TLE) is a common neurological disorder often requiring accurate lateralization of the epileptogenic focus for effective treatment.
- Current methods for lateralization can be invasive or lack sufficient precision.
- Advanced MRI techniques offer potential for non-invasive assessment of brain structures like the hippocampus.
Purpose of the Study:
- To compare Mean Apparent Propagator MRI (MAP-MRI) and Diffusion Tensor Imaging (DTI) parameters against traditional MRI measures for non-invasive lateralization of TLE.
- To investigate the correlation between DTI and MAP-MRI metrics and cognitive function in TLE patients.
Main Methods:
- Retrospective analysis of unilateral TLE patients and matched controls.
- Acquisition of T1-weighted MPRAGE, FLAIR, DTI, and MAP-MRI data from bilateral hippocampi.
- Calculation of sensitivity, specificity, lateralization ratios, effect sizes, and Pearson correlations.
Main Results:
- MAP-MRI parameter 'return to the plane probability' (RTPP) demonstrated the strongest effect size for lateralizing the epileptogenic hippocampus (86.36% ratio).
- Diffusion metrics including Mean Diffusivity (MD), Radial Diffusivity (RD), and Mean Square Displacement (MSD) negatively correlated with delayed recall.
- Other DTI/MAP-MRI parameters like RTAP, RTOP, and Fractional Anisotropy (FA) showed positive correlations with cognitive measures.
Conclusions:
- MAP-MRI parameters are effective radiologic biomarkers for non-invasive lateralization of epileptogenic foci in TLE.
- These advanced MRI techniques provide valuable insights into the relationship between microstructural brain changes and cognitive deficits in TLE.
