Localization of epileptogenic foci using 3D-ASL MRI
磁共振3DASL成像在癫痫致痫灶定位中的应用

摘要

目的 应用磁共振3DASL技术获取癫痫患者发作后脑CBF图像，应用相关软件提取基于标准脑AAL模板大脑90个脑区的CBF值并结合脑电图，初步探讨磁共振3DASL技术在癫痫致痫灶定位中的价值。方法 回顾性分析2023年1月至2024年5月期间，于包头医学院第二附属医院门诊和住院确诊为癫痫的20例患者，症状发作3日内有完整的EEG和磁共振3DASL检查结果，并招募对照组20例。使用基于MATLAB R2021b平台的SPM12软件将CBF图DICOM格式转换成NifTI格式；将CBF图像标准化至蒙特利尔神经研究所（MNI）标准空间；用DPABI软件采用“Mean Division”方法将所有数据进行归一化处理；将归一化后的图像进行平滑处理（FWHM=8mm），最后将平滑后的CBF图像经DPABI软件提取基于AAL模板大脑灰质90个脑区的CBF值。将对照组大脑血流平均值+1.5倍标准差(Mean+1.5SD)作为标准，大于该值为高灌注，病例组每个被试与该标准比较筛选出高灌注脑区，并与EEG异常放电区进行一致性分析。结果 对照组左侧海马CBF值高于病例组（p<0.05）。对照组在左侧中央前回、左眶部额上回、右眶部额上回、左眶部额中回、右眶部额中回、左岛盖部额下回、左三角部额下回、左眶部额下回、左眶内额上回、右眶内额上回、左中央后回CBF值低于病例组（p<0.05）。病例组高灌注脑区与脑电图异常放电区具有较高一致性（κ=0.857）。结论 3DASL在癫痫发作后早期可观察到局部灌注异常，其空间分布与EEG异常放电区具有较高一致性，提示其可作为多模态评估中的辅助定位指标。

Abstract

Objective To acquire cerebral blood flow (CBF) images of epilepsy patients after seizures using magnetic resonance 3D arterial spin labeling (3DASL) technology, extract CBF values of 90 brain regions based on the standard Automated Anatomical Labeling (AAL) template via relevant software, and combine these data with electroencephalography (EEG) results to preliminarily explore the value of magnetic resonance 3DASL technology in localizing epileptogenic foci.
Methods A retrospective analysis was conducted on 20 patients diagnosed with epilepsy in the outpatient and inpatient departments of the Second Affiliated Hospital of Baotou Medical College between January 2023 and May 2024. All patients had complete EEG and magnetic resonance 3DASL examination results within 3 days after symptom onset. A control group of 20 subjects was also recruited. The SPM12 software based on the MATLAB R2021b platform was used to convert CBF images from DICOM format to NifTI format, and to normalize the CBF images to the standard space of the Montreal Neurological Institute (MNI). All data were normalized using the “Mean Division” method with DPABI software, followed by spatial smoothing of the normalized images (full width at half maximum [FWHM] = 8 mm). Finally, the CBF values of 90 gray matter brain regions based on the AAL template were extracted from the smoothed CBF images using DPABI software. The threshold for hyperperfusion was defined as the mean CBF value of the control group plus 1.5 times the standard deviation (Mean + 1.5SD). For each subject in the patient group, brain regions with CBF values exceeding this threshold were identified as hyperperfusion regions. Consistency analysis was then performed between these hyperperfusion regions and the regions of abnormal EEG discharges.
Results The CBF value of the left hippocampus in the control group was significantly higher than that in the patient group (p<0.05). In contrast, the CBF values of the control group in the left precentral gyrus, left orbital superior frontal gyrus, right orbital superior frontal gyrus, left orbital middle frontal gyrus, right orbital middle frontal gyrus, left opercular inferior frontal gyrus, left triangular inferior frontal gyrus, left orbital inferior frontal gyrus, left orbital internal superior frontal gyrus, right orbital internal superior frontal gyrus, and left postcentral gyrus were significantly lower than those in the patient group (p<0.05). There was a high consistency between the hyperperfusion brain regions in the patient group and the regions of abnormal EEG discharges (κ=0.857).
Conclusion   3DASL can detect local perfusion abnormalities in the early stage after epileptic seizures. The spatial distribution of these abnormalities shows high consistency with the regions of abnormal EEG discharges, suggesting that 3DASL may serve as an auxiliary localization index in multimodal evaluation.