MRI diagnosis of cortical dysplasia in the immature brain

Abstract

Introduction. Cortical dysplasias (CDs) encompass a wide variety of disorders that in most cases lead to epilepsy, especially in infants and young children. MRI diagnosis of CDs is a major part of presurgical examination of pediatric patients with resistant focal epilepsy.Aim. To identify MR markers of CD in the immature brain and develop an MRI protocol for early diagnosis of CDs.Materials and methods. Children aged <2 y.o. (total 128) diagnosed with focal epilepsy were examined over 2017-2019. All MRI scans were performed using the GE 3 T system (General Electric, USA) in the standard MR sequences including T2WI FSE, T1 SE, FLAIR, DWI, SWAN, and FSPGR BRAVO supported with anesthesiological assistance. Аll patients were divided into 3 groups according to the degree of brain maturity; of those, 28 patients had MR signs of CD.Results. The rate of detection of small-size cortical malformations, such as nodular heterotopies or focal cortical dysplasias was significantly higher in groups of patients whose brains (according to MR images) were at the infantile or adult phases of myelination. In children with the isointensive phase myelination, only large cortical dysplasias could be identified. In the first phase, the focal malformations had low amplitude signals in T2-weighted images and high amplitude signals in T1, unlike those in adult patients. In the isointensive phase, the quality of visualization was significantly reduced and provided poor diagnostic information.Conclusion. The results confirm the diagnostic significance of early (before age of 5 months) MRI testing in cases with suspected CD-associated focal epilepsy. However, at the period between 5 and 12 months of age, MR imaging was ineffective for CD diagnosing. Later, in the period from 12 to 15 months, the MRI ability to identify the CDs gradually increased. We consider the standard T2 weighted images with high TR values, the most effective MR modality for diagnosing CDs in young children.