基于独立分量分析去除脑电中眨眼和水平扫视的伪迹

目的 利用独立分量分析方法(ICA)将混合在观测信号中相互独立的源信号分离出来.方法 记录3个正常人自然眨眼和水平扫视条件下7道脑电信号和2道眼电信号,选取7道脑电信号进行处理,2道眼电信号用来指示干扰源的情况.使用扩展相似对角化算法(JADE)将脑电信号分解成多个独立分量,同时利用伪迹脑地形图特征,判断出与眼电伪迹相...     

基于独立分量分析的自适应最大熵算法对脑电干扰的识别与剔除

目的 提出一种在脑电信号采集过程中自动识别和剔除各种干扰的新方法.方法 将独立分量分析(ICA)最大熵算法和非线性参数阈值设定相结合.首先对ICA最大熵算法进行自适应改进,并将其用于对包含肌电、眼动等各种干扰的19导脑电信号进行独立分量分解;然后对各独立成分进行3个参数的非线性分析,通过设定的阈值,自动识别出其中的伪迹成分;在去除识别出的各伪迹的独立成分后,将其余独立成分反投影到头皮各电极处,得到去除干扰后较为纯净的脑电信号.结果 研究表明,基于盲源分离技术的自适应最大熵算法实现了脑电信号与其中所包含的多种干扰成分的分离,通过信号的重建可实现对不同来源干扰的剔除.结论 自适应最大熵算法是生理信号消噪研究中一种有潜力的方法.     

脊髓型颈椎病前、后路手术中经颅电刺激运动诱发电位与皮层体感诱发电位的联合监护作用

目的 探讨脊髓型颈椎病(cervical Spondylitic myelopathy,CSM)手术中经颅电刺激运动诱发电位(transcranial electrical stimulation motor evoked potential,TES-MEP)和皮层体感诱发电位(cortical somatosensory evoked potential,CSEP)联合监测脊髓功能的临床应用价值.方法 选自CSM手术中同时记录双侧胫前肌、足底躅短屈肌、鱼际肌的TES-MEP和双侧胫后神经和尺神经的CSEP共135例.根据TES-MEP、CSEP和联合监护结果与术后脊髓运动和感觉功能的比较,进行相关的统计学分析.结果 术中TES-MEP、CSEP、联合监护的成功检出率分别为87.4%、97.8%和100%.因手术操作引起诱发电位阳性共9例占6.7%.TES-MEP、CSEP判断脊髓运动功能的灵敏度分别为100%和83.3%,而判断脊髓感觉功能的灵敏度分别为77.8%和100%;联合监护的灵敏度和特异度均100%.结论 联合监护的成功检出率和准确性明显高于单一方法监护;手术操作引起诱发电位阳性的原因包括:前路椎管内的彻底减压、恢复椎间隙高度和生理弯曲的椎间植骨块或钛网植骨、合并后纵韧带骨化症的后路电磨惟板开槽,以及后路转前路手术时引流管不通的血肿压迫等.

Abstract：

Objective To evaluate of the efficacy of transcranial electrical stimulation motor evoked potential (TES-MEP)in combination with cortical somatosensory evoked potential (CSEP) monitoring during the anterior or posterior approach spinal surgery for cervical spondylitie myelopathy (CSM).Methods TES-MEP on the bilateral anterior tibial muscle and flexor hallucal brevis and thenar muscles and CSEP on the bilateral posterior tibial nerve and ulnar nerve were observed simultaneously in 135 patients during spinal surgery.Intravenous anesthesia was employed in all the patients.The results of TES-MEP,CSEP and combined monitoring were analyzed statistically.Pre-oporative and post-operative motor and sensory functions of the spinal cord were compared. Result Success rate of TES-MEP,CSEP and the combined monitoring was 87.4%.97.8%and 100%,respectively.Out of 135 patients,nine patients (6.7%) were detected with the positive evoked potentials due to surgical operation.The sensitivity of TES-MEP and CSEP in assessing the spinal cord motor function was 100%and 83.3%,respectively,while that in assessing the spinal cord sensory function was 77.8%and 100%,respectively.The sensitivity and specificity of the combined monitoring was both 100%. Conclusion The successful detection rate and accuracy of the combined monitoring for spinal cord function are apparently higher than that of simple TES-MEP or CSEP.The causes for operative maneuvers evoking a positive evoked potential include complete anterior decompression of the spinal canal,intervertebral bone graft,laminoplasty for OPLL and hematoma compression caused by a failed drainage in a posterior-anterior approach surgery.     

脑氧饱和度与体感诱发电位在颈动脉内膜手术中的监测作用比较

目的　比较脑氧饱和度 (rSO2 % )和体感诱发电位(N3 5)对全麻下颈动脉内膜手术术中脑血供变化的监测作用。方法　记录 1 0例颈动脉内膜剥脱手术患者围手术期rSO2 %、N3 5及认知功能变化 ,常规监测MAP、HR与SpO2 。结果　在夹闭和开放颈动脉时 ,rSO2 %变化差异有统计学意义 (P <0 0 5 )。围手术期患者未发生认知功能障碍。结论　在颈动脉内膜手术中rSO2 %要比N3 5波幅更早地发现由于脑氧的变化而产生的脑血供改变 ,rSO2 %在反映脑区的血流灌注变化方面明显优于体感诱发电位     

人颈髓诱发电位的波形识别及频谱分析

本文介绍颈髓诱发电位的计算机处理方法。颈髓诱发电位是研究脊髓功能的客观指标,在理论上和临床应用中均有实际意义。生物电信号的计算机处理,不但可以提取更多有意义的信息量,从而对信号进行动态的和定量的分析,而且可使测试结果准确可靠,省力省时,因此在生物医学研究中得到广泛应用。     

红藻酸致大鼠癫痫模型短潜伏期体感诱发电位分析

目的：了解癫痫发作时大脑神经元的功能状态。方法：２０只红藻酸致痫大鼠于癫痫发作前、急性发作期、慢性发作期经正中神经刺激对短潜伏期体感诱发电位（ＳＬＳＥＰ）进行测定。结果：大鼠ＳＬＳＥＰ波形为一小的Ｎ１波后接一大的Ｐ１波；癫痫急性发作期改变为Ｎ１、Ｐ１波的ＰＬ延长，波幅降低，有３例波形缺失；慢性发作期仅Ｐ１波的Ｐ１较前缩短。结论：癫痫急性发作期Ｎ１、Ｐ１波的改变与兴奋性氨基酸的神经元毒性作用及继发性缺血、缺氧致神经元损伤有关。慢性发作期Ｐ１波缩短的机理有待进一步研究。     

脑卒中后功能网络的独立成分分析研究进展

卒中是危害中老年健康和生命的主要疾病之一,多伴随运动功能障碍、言语障碍及认知障碍等,严重影响其预后及生活质量。ICA作为一种盲源分离技术,近年来常用于脑血管病的脑网络分析,通过分析多维观测数据间的高阶相关性,在源信号和混合矩阵均未知的情况下,找出相互独立的隐含信息成分,完成独立源信号的提取,为卒中患者的脑网络损伤提供了更有力客观的神经影像学方法。本文总结近年来ICA在卒中后偏瘫、言语障碍、认知障碍等方面的研究进展,而卒中患者功能异常往往有着脑网络水平的损伤的致病原因,后续康复和临床研究需要多加考虑相应的因素。     

高压氧治疗对中重型颅脑损伤患者脑干和体感诱发电位的影响及疗效分析

目的 观察高压氧(hyperbaric oxygen,HBO)治疗对外伤性中重型颅脑损伤患者脑干听觉诱发电位(bralnstem auditory evoked potential,BAEP)、体感诱发电位(somatic evoked potential,SEP)的影响及其治疗效果.方法 134例外伤性中重型颅脑损伤患者分为对照组67例和HBO治疗组67例.对照组采用必要的神经外科处理及常规药物治疗;HBO组在对照组治疗的基础上,病情稳定后加用3个疗程的HBO治疗.治疗前后行BAEP、SEP检查及格拉斯哥昏迷评分(GCS),伤后6个月随访行格拉斯哥预后评分(GOS).结果 治疗前2组患者BAEP、SEP异常率及GCS评分差异无统计学意义(P>0.05);治疗后对照组BAEP明显改善(P<0.05),SEP改善更为显著(P<0.01),GCS评分明显升高(P<0.05),HBO组BAEP、SEP改善均有统计学意义(P<0.01),GCS评分提高有统计学意义(P<0.01);治疗后HBO组BAEP、SEP异常率与对照组比较差异有统计学意义(P<0.01),GCS评分与对照组比较差异有统计学意义(P<0.05);伤后6个月GOS评分显示HBO组预后良好患者较对照组明显增多(P<0.01),死亡率则明显降低(P<0.05).结论 HBO可明显改善中重型颅脑损伤患者BAEP及SEP的异常情况,提高临床疗效.     

高压氧治疗对中重型颅脑损伤患者脑干和体感诱发电位的影响及疗效分析

目的 观察高压氧(hyperbaric oxygen,HBO)治疗对外伤性中重型颅脑损伤患者脑干听觉诱发电位(bralnstem auditory evoked potential,BAEP)、体感诱发电位(somatic evoked potential,SEP)的影响及其治疗效果.方法 134例外伤性中重型颅脑损伤患者分为对照组67例和HBO治疗组67例.对照组采用必要的神经外科处理及常规药物治疗;HBO组在对照组治疗的基础上,病情稳定后加用3个疗程的HBO治疗.治疗前后行BAEP、SEP检查及格拉斯哥昏迷评分(GCS),伤后6个月随访行格拉斯哥预后评分(GOS).结果 治疗前2组患者BAEP、SEP异常率及GCS评分差异无统计学意义(P>0.05);治疗后对照组BAEP明显改善(P<0.05),SEP改善更为显著(P<0.01),GCS评分明显升高(P<0.05),HBO组BAEP、SEP改善均有统计学意义(P<0.01),GCS评分提高有统计学意义(P<0.01);治疗后HBO组BAEP、SEP异常率与对照组比较差异有统计学意义(P<0.01),GCS评分与对照组比较差异有统计学意义(P<0.05);伤后6个月GOS评分显示HBO组预后良好患者较对照组明显增多(P<0.01),死亡率则明显降低(P<0.05).结论 HBO可明显改善中重型颅脑损伤患者BAEP及SEP的异常情况,提高临床疗效.     

高压氧治疗对中重型颅脑损伤患者脑干和体感诱发电位的影响及疗效分析

目的 观察高压氧(hyperbaric oxygen,HBO)治疗对外伤性中重型颅脑损伤患者脑干听觉诱发电位(bralnstem auditory evoked potential,BAEP)、体感诱发电位(somatic evoked potential,SEP)的影响及其治疗效果.方法 134例外伤性中重型颅脑损伤患者分为对照组67例和HBO治疗组67例.对照组采用必要的神经外科处理及常规药物治疗;HBO组在对照组治疗的基础上,病情稳定后加用3个疗程的HBO治疗.治疗前后行BAEP、SEP检查及格拉斯哥昏迷评分(GCS),伤后6个月随访行格拉斯哥预后评分(GOS).结果 治疗前2组患者BAEP、SEP异常率及GCS评分差异无统计学意义(P>0.05);治疗后对照组BAEP明显改善(P<0.05),SEP改善更为显著(P<0.01),GCS评分明显升高(P<0.05),HBO组BAEP、SEP改善均有统计学意义(P<0.01),GCS评分提高有统计学意义(P<0.01);治疗后HBO组BAEP、SEP异常率与对照组比较差异有统计学意义(P<0.01),GCS评分与对照组比较差异有统计学意义(P<0.05);伤后6个月GOS评分显示HBO组预后良好患者较对照组明显增多(P<0.01),死亡率则明显降低(P<0.05).结论 HBO可明显改善中重型颅脑损伤患者BAEP及SEP的异常情况,提高临床疗效.     

不同视刺激的视诱发电位的波形特征和规律

不同视刺激的人脑视诱发电位（ＶＥＰ）有着不同的波形特征和规律。光闪ＶＥＰ随刺激亮度增高，峰时缩短，波幅增大；频闪刺激时反应出现多峰，随频率增高波幅逐渐下降，同步的ＶＥＰ的空间频率极限接近刺激频率３０次／Ｓ。棋盘格ＶＥＰ随空间频率由低增高，波幅迅速增大。至某一空间频率时，再增高空间频率，波幅又迅速减小，对某一空间频率反应最大。对比度ＶＥＰ波幅开始随对比度增大而迅速增大，峰时开始则随对比度增大而迅速缩短。增至某一对比度时，波幅上升明显减慢，峰时缩短减少，对比度增至１００％时，波幅达到最大值，峰时变化甚小；红绿蓝三基色ＶＥＰ，波形上有明显差别，波形较上述几种波形复杂。红色刺激的ＶＥＰ峰时最短，蓝色刺激的ＶＥＰ峰时最长。两负波波幅比值随波长变化呈红－绿色或红－蓝色拮抗。     

鼻内镜术中听觉诱发电位指数及血流动力学变化

目的调查鼻内镜术中知晓的发生,研究其与听觉诱发电位指数(AEPI)和血流动力学变化的关系。方法对30例鼻内镜手术病人,麻醉采用静脉注射1%利多卡因2 ml、芬太尼3μg/kg、丙泊酚2 mg/kg和琥珀胆碱2 mg/kg麻醉诱导,以丙泊酚靶控输注(TCI)、芬太尼、阿曲库胺维持麻醉,监测平均动脉压(MAP)、心率(HR)和AEPI。麻醉医生根据血流动力学和经验调整丙泊酚TCI效应室浓度以控制麻醉深度。另安排一耳鼻喉科医生负责记录基础值、诱导后、插管后、置入鼻内镜后、鼻腔填塞及术毕时各参数。结果所有患者麻醉诱导、手术顺利,麻醉诱导后全组患者MAP和HR显著下降(P<0.05),全组与诱导后相比,血流动力学无统计学差异,全组患者基础AEPI值平均为76.9±9.6,诱导后明显下降(P<0.01);全组患者中3例出现术中知晓,发生率为10%,知晓发生时间分别在置入鼻内镜、鼻腔填塞时;全部知晓者无疼痛回忆。3例患者出现术中知晓时AEPI值均高于40,其余27例患者AEPI值无一例高于40。结论鼻内镜手术时间短,凭经验和血流动力学变化实施全身麻醉,术中知晓发生率高,表现为AEPI值偏高;以AEPI作为麻醉深度的指标,可减少或防止术中知晓的发生。     

不同强度健美操锻炼对女大学生健康体适能及视觉诱发电位的影响

目的:探讨8周二级和五级健身健美操锻炼对女大学生健康体适能及视觉诱发电位指标的影响。方法:选取45名健康女大学生志愿者,随机分为空白对照组、二级锻炼组和五级锻炼组3组。其中,二级锻炼组进行《大众健美操锻炼标准》二级规定动作锻炼(节奏为135拍/分钟),五级锻炼组进行五级规定动作锻炼(节奏为148拍/分钟),每次锻炼1小时,每周3次,为期8周;空白对照组按原来作息规律生活。测试三组学生实验前后的健康体适能指标。采用NDI-200(海神号)神经电检诊仪分别于实验前、后,记录分析所有受试者中方格图形翻转刺激下视觉诱发电位的波形,并比较其潜伏期、峰间期、峰峰值的变化。结果:①与实验前相比,两锻炼组实验后仰卧起坐次数、最大摄氧量值、坐位体前屈值均显著增加(P<0.01),五级锻炼组增值均大于二级锻炼组。②与实验前相比,二级和五级锻炼组视觉诱发电位潜伏期均缩短,其中五级锻炼组P100潜伏期显著缩短(P<0.01)。③实验前后三组视觉诱发电位峰间期、峰峰值均无显著性差异(P>0.05)。结论:持续8周的健身健美操锻炼能够显著提高锻炼者的健康体适能水平及缩短视觉诱发电位P100潜伏期,且五级锻炼组效果大于二级锻炼组。     

人脑体感诱发电位的研究及其在人-机-环境系统工程中应用 正常成年人体感诱发电位特征初探

航天员在宇宙飞行上升、返回和着陆过程中,都会受到冲击力的作用,冲击力会给人造成疼痛及损伤。为了探索判断急性痛的客观指标而开展本课题研究。研究结果表明,正常成年人的体感诱发电位是较稳定的,它为进一步的深入研究与应用奠定了良好的基础。     

Utility of Motor and Somatosensory Evoked Potentials for Neural Thermoprotection in Ablations of Musculoskeletal Tumors

PurposeTo characterize the utility of monitoring transcranial electrical motor evoked potentials (TCeMEPs) and somatosensory evoked potentials (SSEPs) for neural thermoprotection during musculoskeletal tumor ablations.Materials and MethodsRetrospective review of 29 patients (16 male; median age, 46 y; range, 7–77 y) who underwent musculoskeletal tumor radiofrequency ablation (n = 8) or cryoablation (n = 22) with intraprocedural TCeMEP and SSEP monitoring was performed. The most common tumor histologies were osteoid osteoma (n = 6), venous malformation (n = 5), sarcoma (n = 5), renal cell carcinoma (n = 4), and non–small-cell lung cancer (n = 3). The most common tumor sites were spine (n = 22) and lower extremities (n = 4). Abnormal TCeMEP change was defined by 100-V increase above baseline threshold activation for a given myotome; abnormal SSEP change was defined by 60% reduction in baseline amplitude and/or 10% increase in latency.ResultsAbnormal changes in TCeMEP (n = 9; 30%) and/or SSEP (n = 5; 17%) occurred in 12 procedures (40%) and did not recover in 5 patients. Patients with unchanged TCeMEP/SSEP activities throughout the procedure (n = 18) did not have motor or sensory symptoms after the procedure; 3 (60%) with unrecovered activity changes and 2 (29%) with transient activity changes had new motor (n = 1) or sensory (n = 4) symptoms. Relative risk for neurologic sequelae for patients with unrecovered TCeMEP/SSEP changes vs those with transient or no changes was 7.50 (95% confidence interval, 1.66–33.9; P = .009).ConclusionsAbnormal activity changes of TCeMEP or SSEP during percutaneous ablative procedures correlate with postprocedural neurologic sequelae.     

Independent component analysis‐based multifiber streamline tractography of the human brain

An independent component analysis‐based approach has been developed to estimate the orientations of two or three crossing fibers in a voxel to conduct human brain streamline tractography from diffusion data acquired along 25 gradient directions at a b‐value of 1000 sec/mm². The approach relies on unmixing signals from fibers mixed within, and spread over, a small cluster of 11 voxels. Simulation studies of diffusion data for two or three crossing fibers at signal‐to‐noise ratios of 15 and 30 suggest the accuracy to determine interfiber angles with independent component analysis is similar to that attained by a gaussian mixture and other multicompartmental models but at two orders of magnitude faster computational speed. Compared to previous multicompartmental models, independent component analysis visually shows good recovery of fiber orientations and tracts in the crossing region of commonly available orthogonal and 60° phantom diffusion datasets. A 3T MRI human studies show that in contrast to conventional streamline tractography and a multicompartment model, independent component analysis shows better recovery of the continuity of fronto‐occipital tracts and cingulum from regions where these tracts are mixed with corpus callosum and other pathways. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Independent component analysis of fMRI data in the complex domain.

In BOLD fMRI a series of MR images is acquired and examined for task-related amplitude changes. These functional changes are small, so it is important to maximize detection efficiency. Virtually all fMRI processing strategies utilize magnitude information and ignore the phase, resulting in an unnecessary loss of efficiency. As the optimum way to model the phase information is not clear, a flexible modeling technique is useful. To analyze complex data sets, independent component analysis (ICA), a data-driven approach, is proposed. In ICA, the data are modeled as spatially independent components multiplied by their respective time-courses. There are thus three possible approaches: 1) the time-courses can be complex-valued, 2) the images can be complex-valued, or 3) both the time-courses and the images can be complex-valued. These analytic approaches are applied to data from a visual stimulation paradigm, and results from three complex analysis models are presented and compared with magnitude-only results. Using the criterion of the number of contiguous activated voxels at a given threshold, an average of 12-23% more voxels are detected by complex-valued ICA estimation at a threshold of /Z/ > 2.5. Additionally, preliminary results from the complex models reveal a phase modulation similar to the magnitude time-course in some voxels, and oppositely modulated in other voxels.     

Independent component analysis for automated decomposition of in vivo magnetic resonance spectra.

Fully automated methods for analyzing MR spectra would be of great benefit for clinical diagnosis, in particular for the extraction of relevant information from large databases for subsequent pattern recognition analysis. Independent component analysis (ICA) provides a means of decomposing signals into their constituent components. This work investigates the use of ICA for automatically extracting features from in vivo MR spectra. After its limits are assessed on artificial data, the method is applied to a set of brain tumor spectra. ICA automatically, and in an unsupervised fashion, decomposes the signals into interpretable components. Moreover, the spectral decomposition achieved by the ICA leads to the separation of some tissue types, which confirms the biochemical relevance of the components.     

Independent component analysis of dynamic contrast-enhanced magnetic resonance images of breast carcinoma: a feasibility study

PURPOSE: To study the possibility of using independent component analysis (ICA) to identify breast lesions as separate hemodynamic sources on dynamic contrast-enhanced (DCE) MR images, as depicted by the passage of contrast medium. MATERIALS AND METHODS: Six patients who were histopathologically confirmed with breast carcinoma underwent DCE MRI with 5 precontrast and 60 postcontrast scans at a time-resolution of 8 s. A spatial ICA algorithm was applied on the DCE MRI data set to extract spatial component maps corresponding to source locations with different signal time-intensity patterns. To verify the present hypothesis of the ability of ICA to reveal tumor voxels as a separate hemodynamic phase, tumor margins were outlined by an experienced radiologist who was blinded from the ICA results, and the manual outlines were compared with the ICA maps. RESULTS: Consistently for each of the six patient study cases, it was found that ICA yields a tumor component map associated with typical tumor enhancement patterns of rapid enhancement with washout or plateau. Tumor outlines manually drawn by the radiologist were in good agreement with the tumor locations depicted in the tumor component maps. CONCLUSION: ICA may provide an objective method for identifying the outlines of enhancing breast tumors on DCE MR images and to automatically extract the tumor signal intensity-time curve for subsequent tracer kinetics analysis.     

Independent component analysis tractography combined with a ball–stick model to isolate intravoxel crossing fibers of the corticospinal tracts in clinical diffusion MRI

The independent component analysis (ICA) tractography method has improved the ability to isolate intravoxel crossing fibers; however, the accuracy of ICA is limited in cases with voxels in local clusters lacking sufficient numbers of fibers with the same orientations. To overcome this limitation, the ICA was combined with a ball–stick model (BSM) [“ICA+BSM”]. An ICA approach is applied to identify crossing fiber components in voxels of small cluster, which are maximally independent in orientation. The eigenvectors of these components are numerically optimized via the subsequent BSM procedure. Simulation studies for two or three crossing fibers demonstrate that ICA+BSM overcomes the limitation of the original ICA method by refining regional ICA solutions in diffusion measurement of a single voxel. It shows 2°–5° of angular errors to isolate two or three fibers, providing a better recovery of simulated fibers compared with ICA alone. Human studies show that ICA+BSM achieves high anatomical correspondence of corticospinal tracts compared with postmortem corticospinal histology, yielding 92.2% true positive detection including both lateral and medial projections, compared with 84.1% for ICA alone. This study demonstrates that the intravoxel crossing fiber problem in clinical diffusion MRI may be sorted out more efficiently by combining ICA with BSM. Magn Reson Med 70:441–453, 2013. © 2012 Wiley Periodicals, Inc.