| Focal cortical dysplasia (FCD) is frequently found in children with epilepsy. It also accounts for the most common cause of intractable epilepsy. However, magnetic resonance imaging (MRI) has limited sensitivity to FCD and provides little information for grading the disease. While the blur of gray and white matter is widely observed in almost all FCD cases, there are few studies to address this feature. Furthermore, although diffusion weighted imaging has been proved to be sensitive to the micro-environmental changes of tissue, the sensitivity of its diffusion parameters to FCD lesions remains unclear.In this study, T1WI and DTI data were acquired to study the blur of gray matter and white matter and the sensitivity of DTI parameters to FCD lesions, respectively. First, to achieve a better outcome of T1WI data preprocessing, the HMRF-EM (Hidden Markov Random Field-Expectation Maximization) algorithm was applied to segment the tissue in a probabilistic approach, as well as to remove bias field effects. Based on the segmentation results, a new feature to characterize the blurred tissue boundary was calculated and compared with the conventional image gradient approach. Thereafter, to minimize the susceptibility artifact in DTI data, eddy current correction was conducted, followed by the intermodal registration using BBR cost function to ensure the precision. Finally, by combining the segmentation results of T1WI data and preprocessed DTI data, eight diffusion tensor parameters in FCD lesions were calculated and compared with those in the contralateral normal tissues at the statistical level. The results showed that significant alterations of these parameters are found in FCD lesions with subcortical white matter hyper-intensity on FLAIR images, even when the potential contamination from other tissues of different types is strictly controlled. Therefore, it is proposed that these diffusion parameters may have the potential to assess the detection as well as grading of FCD. |
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