Multimodality Image Post-processing in Detection of Extratemporal MRI-Negative Cortical Dysplasia.

Wen-Han Hu,Kai Zhang,Xiao-Qiu Shao,Jian-Guo Zhang,Lin Ai,Xiu Wang,Yan-Shan Ma,Jun-Ju Li,Li-Na Liu

doi:10.3389/fneur.2018.00450

Abstract

Purpose: To determine the diagnostic value of individual image post-processing techniques in a series of patients who underwent extratemporal operations for histologically proven, MRI-negative focal cortical dysplasia (FCD).Methods: The morphometric analysis program (MAP), PET/MRI co-registration and statistical parametric mapping (SPM) analysis of PET (SPM-PET) techniques were analyzed in 33 consecutive patients. The epileptogenic zone (EZ) assumed by MAP, PET/MRI, and SPM-PET was compared with the location of the FCD lesions determined by stereoelectroencephalography (SEEG) and histopathological study. The detection rate of each modality was statistically compared.Results: Three lesions were simultaneously detected by the three post-processing methods, while two lesions were only MAP positive, and 8 were only PET/MRI positive. The detection rate of MAP, PET/MRI, SPM-PET and the combination of the three modalities was 24.2, 90.9, 57.6, and 97.0%, respectively. Taking the pathological subtype into account, no type I lesions were detected by MAP, and PET/MRI was the most sensitive method for detecting FCD types II and IIA. During a mean follow-up period of 22.94 months, seizure freedom was attained in 26/33 patients (78.8%) after focal corticectomy.Conclusions: MAP, PET/MRI, and SPM-PET provide complementary information for FCD detection, intracranial electrode design, and lesion resection. PET/MRI was particularly useful, with the highest detection rate of extratemporal MRI-negative FCD.

Highlights

The success of epilepsy surgery depends on the precise localization and complete resection of the epileptogenic zone (EZ)
Among all the patients who underwent a resective epilepsy surgery in our institution between June 2014 and June 2016, we included consecutive patients who met the following criteria: [1] the epileptogenic lesion was undetected by conventional visual analysis on MRI scanning; [2] only extratemporal resection was performed; [3] the pathological finding was focal cortical dysplasia (FCD); [4] the patient was over 5 years old [12, 13]; [5] the post-surgical follow-up was over 12 months and [6] no cranial surgery was performed previously (Figure 1)
The FCD were located in frontal lobe in 25 patients, insular lobe in 6 patients, frontoparietal lobe in 1 patient and occipital lobe in 1 patient

Summary

Introduction

The success of epilepsy surgery depends on the precise localization and complete resection of the epileptogenic zone (EZ). Extratemporal epilepsy accounts for 34% of epilepsy cases [1] and its surgical management is challenging due to difficulties in EZ localizing and subsequent poor seizure outcomes, especially in MRI-negative cases [2, 3]. The main pathological substrate underlying MRI-negative extratemporal epilepsy is focal cortical dysplasia (FCD) [4]. Quite a number of studies have reported that image post-processing techniques, including the morphometric analysis program (MAP), PET/MRI co-registration and statistical parametric mapping (SPM) analysis of PET (SPM-PET), could improve the detection of MRI-negative FCD [8,9,10,11].

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