Abstracts

Rationale: Type II focal cortical dysplasia (FCD), characterized by gray-white matter junction blurring, increased fluid-attenuated inversion-recovery (FLAIR) gray matter signal, abnormal gyration/sulcation, increased cortical thickness, and transmantle sign on MRI, is a common histopathological substrate in focal epilepsy. This study explored the spatial distribution of MRI abnormalities across the dysplastic sulcus in patients with FCD type II using quantitative MRI post-processing techniques. Methods: Morphometric MRI analysis with morphometric analysis program(MAP) and normalized FLAIR signal intensity (nFSI) analysis were applied to retrospectively analyze the MRI data of 58 consecutive patients with histopathologically confirmed type II FCD lesions. The z values derived from MAP and nFSI represented the severity of the MRI abnormalities. To better describe the spatial distribution features of these MRI abnormalities, we firstly divided the dysplastic sulcus into the bottom part and the non-bottom part, then spatial distribution type 1, 2 and 3 were arbitrarily defined as the MRI abnormalities (z value > threshold) located in the bottom part, both the bottom and non-bottom parts, and the non-bottom part, respectively. For type 2, volumes of abnormalities were standardized (divided by the corresponding volumes of the whole bottom or non-bottom part). The mean z values and corresponding standardized volumes of MRI abnormalities were compared between the bottom and non-bottom part. Results: MRI abnormalities were detected by quantitative techniques in 42 of 58 enrolled patients. Among the 42 patients, 38 and 26 patients showed gray-white matter junction blurring and FLAIR gray matter signal change respectively, which were the two most common abnormal MRI features. Gray-white matter junction blurring manifested as type 1, 2 and 3 in 24, 13 and one patients respectively, and the corresponding counts for FLAIR gray matter signal change were 12, 13 and one patients. For the two most common MRI abnormalities spatially manifested as type 2, higher mean z values and larger corresponding standardized volumes of abnormalities were found in the bottom part. Conclusions: The two most common abnormal MRI features of type II FCD were gray-white matter junction blurring and FLAIR gray matter signal change, which are recognized mostly in the bottom part of the dysplastic sulcus. Funding: Grants from the capital (China) health research and development of special fund (2016-1-1071) and Capital Medical University Basic and Clinical Cooperative Research Project(17JL05)