Malformations of cortical development are arranged in different ways. Recently, the ILAE published a consensus classification incorporating pathological, imaging, and genetic findings (Blumcke et al. 2011). Some lesions (namely FCD 2B) from this classification are clearly visible on MRI and pathologically classified with a high concordance between different pathologists. If they are fully resected, seizure freedom rate is > 80 %. Other lesions (namely FCD 1) are more difficult to detect or “unvisible” even with voxel-based MRI analyses and harbored with a high interrater-variability between different pathologists. Chance of postsurgical seizure freedom is distinctly < 50 %. A patient will likely benefit from surgery if a distinct MRI lesion is found underlining the importance of high-quality MRI acquisition and interpretation.