Resting-state Functional MRI Study For Epileptic Activation Detection In Focal Epilepsy

Objective:To comparatively investigate the specific alteration patterns of ALFF(amplitude of low frequency fluctuation) and EEG-fMRI (Electroencephalogram-correlated functional MRI) for detection of epileptic activation, and assess the value of ALFF technique for localization of focal epilepsy.Materials and methods:Twenty-four partial epilepsy patients with specific pathological lesions were included, simultaneous EEG-fMRI data were acquired on GE 1.5T MRI scanner (17 cases) and SIEMENS 3.0T MRI scanner (7 cases). General linear model (GLM)-based analysis was used to measure interictal epileptiform discharges (IEDs) related fMRI activation. Subsequently, ALFF of individual patient was compared with the baseline data of a large sample normal subjects using two-sample t test (p<0.05 alphasim corrected), which was employed to detect alteration of ALFF value in the patient with focal epilepsy. The fMRI results from two analysis approaches were validated by the localization result in clinic.Results:A total of 36 sessions of EEG-fMRI data were successfully acquired, both the analyzes had obvious BOLD signal detected. For GLM based analysis of EEG-fMRI data,15 sessions (15/36,41.66%) were concordances with clinical location results. For ALFF analysis,24 sessions (24/36,66.66%) were concordances with clinical location results. There were 9 sessions (9/36,25.00%) both techniques the results were consistent with each other and also with the clinical location results, and 6 sessions (6/36,16.67%) that both the results were inconsistent with the clinical location results.Conclusion:EEG-fMRI has capability for detection of epileptic activation.ALFF based fMRI technique can achieve a better result of epileptic activation detection without simultaneous EEG information, which provides a new fMRI analysis techniques for epileptic activation detection.Objective:To investigate the specific alteration patterns of ALFF and functional connectivity in patients with medial temporal lobe epilepsy, and evaluate the value of the combining of these two methods in the detection of epileptic activity.Materials and methods:47 patients with mTLE and 32 matched healthy controls underwent resting-state fMRI, all the patients were detected to have interictal epileptic discharges on simultaneous EEG recordings. We performed a standardization calculation using the ALFF and FCD data after pre-processing, hen produced an ALFF-FCD contrast map. The difference of ALFF, FCD and ALFF-FCD between mTLE patients and controls were analysed with 2-sample test. Moreover, to evaluate the value of these three parameters in lateralization, we performed a confirmatory test using ROI-based comparison of each imaging parameter within the mesial temporal structures by Dichotomie/ROC curve. Then we performed multiple regression analyses to observe relationship between IEDs and duration of epilepsy with the changed brain regions of FCD, ALFF and ALFF-FCD,.Results:Compared with the controls, interictal epileptic discharges caused increased ALFF and decreased FCD in the temporal structures of lesioned side, and both decreases of ALFF and FCD in default mode regions. ROI based analyses revealed that the parameters of ALFF-FCD could more effectively to differentiate the patients from the HCs than parameter of ALFF or FCD (accuracy=0.95 for LmTLE vs. HC, and accuracy= 0.92 for RmTLE vs. HC). Voxel-based correlations with numbers of IEDs showed positive correlation in the mesial temporal structures (mostly ipsilateral to the epileptogenic side) with ALFF, and negative correlation with FCD. The posterior cingulate cortex and parietal cortex showed negative correlation with both ALFF and FCD. Correlation with epilepsy durations showed negative correlation was found in the mesial temporal structures, posterior cingulate cortex and parietal cortex for both ALFF and FCD. Positive correlation was found to be with the ALFF-FCD coupling strengths in the parietal cortex(P<0.05, FDR correction).Conclusion:The specific alteration patterns of amplitude and connectivity in epileptogenic focus can increase the efficiency in epileptic activation detection. The chronic impairment from epilepsy led to both decreases of ALFF and FCD in default mode regions. Investigation on imaging coupling provides synergistic approach to unravel the pathological features of epilepsy.