Clinical Application of 7T Magnetic Resonance Imaging in Patients with Focal Cortical Dysplasia IIa and Epilepsy

Abstract

<b><i>Background:</i></b> Focal cortical dysplasia (FCD) is one of the most important pathogenic findings in patients with extratemporal lobe epilepsy. Magnetic resonance imaging (MRI)-negative is the most important negative factor to predict postoperative seizure freedom; however, FCD-I and part of FCD-IIa are MRI-negative on routine MRI. <b><i>Objectives:</i></b> To explore the diagnostic values of 7T MRI and its new scan sequences in epilepsy patients with FCD-IIa. <b><i>Methods:</i></b> To include patients with focal seizure and suspicious focal abnormal imaging on 3T MRI during preoperative evaluation and perform a 7T MRI scan with white matter-suppressed (WMS) and gray-white matter tissue border enhancement (GWBE) sequences, resective epilepsy surgery, and postoperative pathological finding of FCD-IIa. The preoperative qualitative and localization significance of 7T MRI and 3T MRI in lesions with FCD-IIa was compared, and then, the imaging characteristics of lesions with FCD-IIa on 7T MRI were analyzed. <b><i>Results:</i></b> Ten cases were enrolled in this study. Seven tesla MRI presented high spatial resolutions and a high signal-to-noise ratio. WMS and GWBE could selectively suppress the signal of special tissue and improved the possibility of FCD findings. FCD-IIa showed abnormal thickness of gray matter and a blurring border and was hypointense on 7T MRI compared with 3T MRI. Seven patients showed improvement in the qualitative diagnosis strength grade of FCD, and 6 subjects showed improvement in the localization strength grade of the lesion border after careful reading of the 7T MR images. Significant differences were found in the qualitative diagnosis of FCD (<i>p</i> &#x3c; 0.05) and localization of the lesion border (<i>p</i> &#x3c; 0.05) between the neuroimaging diagnoses based on 3T MRI and the findings based on 7T MRI. <b><i>Conclusion:</i></b> 7T MRI with WMS and GWBE sequences shows application value in the preoperative imaging diagnosis of lesions with FCD-IIa in epilepsy patients.