Abstracts

Rationale: Detection of Focal Cortical Dysplasias (FCDs) on MRI can be challenging, as FCDs may be very subtle in appearance. MRI post-processing has been demonstrated to be effective in identifying subtle focal cortical dysplasia in patients whose MRI scans were interpreted as normal by visual analysis in adult patients with intractable epilepsy. Morphometric Analysis Program (MAP) utilizes a voxel-based post-processing method which can highlight brain areas with blurred grey-white matter junction and abnormal gyration, and has been validated in adults to improve detection of FCDs. Automated analysis can also detect abnormal areas that do not necessarily correlate with other non-invasive presurgical modalities, particularly in children. We aim to investigate whether MRI post-processing could be adapted to detect FCDs in a pediatric population with non-lesional MRIs. Methods: We included 20 patients between the ages of 2 and 18 years (mean+- SD 10.5+- 4.9), with intractable focal epilepsy and non-lesional MRI's which were conducted as part of a pre-surgical workup. We included patients who underwent resective epilepsy surgery or intracranial electrode implantation. Automated Morphometric Analysis Program (MAP) analysis was performed against a control group of 40 pediatric patients with normal MRI obtained for reasons other than seizures (vomiting, double vision or dizziness). The control group included 20 MRI scans in the age group 2-6 years and 20 scans in the age group 6-14 years. Patients above 14 years of age were referenced to a normative adult database. Generated z-score maps derived from T1 images, referenced to healthy pediatric controls for each of 20 cases were obtained. MAP Junctional images were assessed which detect blurring of the gray-white matter junction. MRIs reported previously as 'non-lesional' were re-reviewed by an experienced pediatric neuroradiologist alongside the MAP images, without any clinical information, to determine whether having the MAP images proved useful in detecting FCDs, then confirming the results by comparing to the areas of surgical resection.  Results: MAP generated 1-6 areas of suspicion per patient (1.95 +-1.45). In all patients, MAP generated 39 areas of suspicion. Upon re-review of MRIs alongside MAP results, the pediatric neuroradiologist guided by MAP results, identified possible FCDs in 9/20 patients, which correlated with the surgical resection in seven patients. There were two patients in which the MAP image were thought to correlate with FCD on MRI re-review but were not concordant with the surgical resection or intracranial EEG data.  Conclusions: Our data suggests that morphometric MRI analysis can be adapted for pediatric patients with non-lesional MRIs. Scrutiny of the presurgical MRI guided by MRI post-processing may increase the diagnostic sensitivity for FCD in comparison with conventional visual analysis alone. Funding: No funding