隐源性癫痫的7T磁共振成像形态与功能研究

Cryptogenic epilepsy accounts for the majority of refractory epilepsy. The pre-operative detection of cryptogenic epileptic foci plays a key role for effective therapy. Considering the low detection rate of cryptogenic epileptic foci on conventional MRI, and the possible underestimate for dual pathology in clinical practice, a pilot study for improved detection of focal cryptogenic epileptic foci is plotted by using 7T MR scanner. Patients with suspected cryptogenic epilepsy by EEG and nuclear medicine but with negative results on conventional MRI are going to be examined on 7T. Whole-brain morphologic scan including conventional MRI sequences, SWI and high resolution volumetric study is designed for subtle epileptic foci display and anatomic-pathologic correlation so as to improve the understanding on imaging findings. Voxel-based analysis is an automated computed quantitative technique to characterize differences in grey matter (GM) and white matter (WM). Cortical thickness measurement based on VBM is designed for objective observation and detection of various pathologic patterns in cryptogenic epileptic foci. The cerebral pathophysiologic and metabolic changes are also investigated by using BOLD and MRS for better understanding of pathophysiologic mechanism in epileptic patients.With ultra-high field of magnet, the quality of images is expected to be superior, with high contrast between GM and WM, it will probably present some differences in cryptogenic epileptic foci.

隐源性癫痫是临床药物难治性癫痫的重要组成部分，提高术前致痫灶的检出是其有效治疗的关键。鉴于目前常规MRI隐源性癫痫病灶检出率较低，且有可能存在多重病理未能全面评价的临床实际问题，本研究拟对临床常规MRI阴性，而脑电图及核医学等检查综合分析提示为局灶隐源性癫痫的病例进行7T超高场磁共振成像检查，进行完整的高分辨率的解剖形态学成像，包括SWI和全脑高分辨率薄层容积成像，观察更接近病理解剖的形态学影像，更敏感地发现更细微的致痫灶，并与手术病理对照，以期对其影像学表现进行归纳总结，提高认识；对全脑容积采集的数据进行基于体素的皮层厚度的分析，以期全面客观地观察隐源性癫痫多重病理的表现，同时结合功能磁共振成像的数据（BOLD+MRS），提高对癫痫脑部病生理及代谢改变的认识，更好地理解癫痫的病理生理机制。

本课题项目已按计划实施并完成的内容包括：①药物难治性癫痫患者手术后病理结果为IIb型局灶性皮质发育不良（Focal Cortical Dysplasia, FCD）的临床、病理特征及影像学特征的总结，共收集8名患者，发现这部分患者绝大多数为儿童起病，临床多表现为复杂部分性癫痫发作；病理学特征表现为皮质构造紊乱、分层不清、灰白质分界不清、神经元形态异常，可见非磷酸化神经丝重链阳性的异型神经元；典型气球样细胞核偏位，胞质均匀嗜酸淡染，多数免疫组织化学表现为波形蛋白、巢蛋白(+)，神经元核抗原、胶质纤维酸性蛋白(-)，这部分内容已发表在《中华神经科杂志》（SCI IF 0.891）上。②对46位药物难治性癫痫患者分别进行3.0TMRI与7TMRI结构相序列的采集（序列包括T1WI、T2WI、T2-FLAIR、SWI），并对结果进行定性对比分析，7T MRI由于其更高的信噪比和分辨率，有可能帮助我们发现常规3TMRI上不易显示的病变，对药物难治性癫痫患者的影像学表现特征及差异进行总结，说明7TMRI存在的意义，撰写文章投稿。③药物难治性癫痫患者中较为常见的是颞叶癫痫伴海马硬化，本项目收集手术后病理诊断为海马硬化的患者25例，应用超高场7T MRI图像实现海马分区并进行各区海马容积测量，与年龄匹配的正常对照对比分析海马萎缩的形式与病理临床及病理特点的关系，撰写文章投稿。