多模态MRI在癫痫中的应用前景

<正> 大部分癫痫患者对抗癫痫药物反应好,然而仍有约20%的患者病情不能通过药物控制而进展为难治性癫痫,对于这些患者手术治疗成为其重要的选择。随现代影像学的发展,目前有很多方法被用于术前评估,其中MRI因具有无创、无放射、多层面成像、空间分辨率高等优点,被认为是近年来最有价值的用于癫痫定位的手段。MRI经历了从结构成像到功能成像,从单模态成像到多模态成像的发展过程,目前应用于癫痫诊断的MRI模态主要有常规MRI、定量MRI、弥散加权成像(diffusion     

基于磁共振技术的血管性认知障碍研究进展

血管性认知障碍目前尚缺乏统一的影像诊断标准,近年来磁共振技术的发展提供了有助 于血管性认知障碍早期诊断的神经影像学标志物。本文从弥散张量成像、磁共振波谱、磁共振磁 敏感加权成像和功能磁共振成像多种磁共振模态对血管性认知障碍的影像特点进行综述。将多种 模态的神经影像学检查方法联合运用有助于提高血管性认知障碍临床诊断的准确率,为进一步的 治疗提供帮助。     

多序列磁共振成像在一例多发性硬化诊断中的应用体会

目的探讨常规磁共振,尤其是弥散加权成像(DWI)、弥散张量成像(DTI)及磁共振波谱成像(1H-MRS)在多发性硬化(MS)诊断中的应用价值。方法 MS患者1例,采用GE Signa 3.0 T EXCITE HDMR系统,8通道头部线圈,进行常规磁共振(T1-flair、FSE-T2WI、T2-flair)、T1-flair增强及DWI、DTI、1H-MRS扫描。ADW4.2工作站进行DWI、DTI、1H-MRS图像后处理,分别测定兴趣区及正常区ADC值、eADC值、FA值,以及NAA、Cho、mI值和NAA/Cr、Cho/Cr、mI/Cr比值。结果常规磁共振病变呈多发圆形、椭圆形、不规则片状T1WI低信号、T2WI高信号,FLAIR高信号,表现符合MS的典型特征;增强扫描病变周边强化,呈不完整环形、半环形或马蹄铁样;DWI显示病变中心呈低信号,边缘呈高信号,病变区ADC值增高,eADC值降低;DTI显示额顶病变区白质纤维溶解、破坏、推移,FA值降低;1H-MRS显示病灶内Cho峰升高,Cho/Cr比值升高,NAA峰轻度降低,NAA/Cr比值轻度降低,mI峰增高。结论多序列磁共振扫描,尤其是DWI、DTI及1H-MRS对MS的诊断、斑块活动性监测及病变分期具有重要临床应用价值。     

轻度创伤性脑损伤后脑功能障碍的研究进展

轻度创伤性颅脑损伤的发生率呈逐年上升趋势,由于缺乏特异性的诊断技术及有效的治疗手段,轻度创伤性脑损伤后脑功能障碍往往迁延不愈,影响患者的工作与生活。对于轻度脑损伤后的病理生理改变及后期脑功能障碍的具体形成机制尚不明确。本文从轻度创伤性脑损伤后脑功能障碍的研究现状、相关神经机制、神经影像学诊断新技术的应用以及治疗手段等进行综述,为其早期诊断、干预治疗等提供新的的理论依据。     

代谢综合征脑磁共振波谱和弥散张量成像的相关性研究

目的了解代谢综合征(MS)患者脑细胞代谢及神经纤维微结构的变化。方法研究对象分为MS组15例,其中男性4例、女性11例;年龄47~70岁,平均年龄(62.60±6.74)岁。对照组17例,其中男性5例、女性12例;年龄50~69岁,平均年龄(58.41±5.52)岁。均予以一般项目及头颅MRI、磁共振波谱(MRS)及MR弥散张量成像(DTI)检查,分析两组N-乙酰天冬氨酸(NAA)、乙酰胆碱(Cho)、肌酸(Cr)及部分各向异性(FA)值检查结果。结果 MS组NAA/Cr、NAA/Cho明显降低,Cho/Cr明显升高;FA值明显降低;NAA/Cr与糖尿病、低密度脂蛋白相关,FA值与高血压病、高脂血症、肥胖相关;NAA/Cr、NAA/Cho与MS病程年限相关(均P<0.05)。结论病程5年以上的MS患者脑细胞代谢及神经纤维微结构已有损害,其程度与代谢异常程度及病程明显相关。     

磁共振成像在肌萎缩侧索硬化症研究中的进展

肌萎缩侧索硬化症是运动神经元病的常见类型,预后差,其诊断主要根据临床表现和神经电生理检查。近年磁共振成像在该病的研究领域已取得了一定进展。常规射频脉冲序列可直观地显示特征性的异常信号。弥散张量成像、磁共振波谱分析等方法能够观察肌萎缩侧索硬化症一系列生化、病理等方面的改变,对疾病的诊断具有一定参考价值,并可能对该病的基础研究有所帮助。     

阿尔茨海默病与轻度认知障碍弥散张量成像研究

目的:应用磁共振弥散张量成像技术(DTI)研究阿尔茨海默病(AD)与轻度认知障碍患者(MCI)脑白质损伤情况。方法:对21例AD患者、15例MCI患者和20名健康志愿者进行脑部DTI扫描后,测量双脑区感兴趣区的各向异性分数值(FA)且进行比较。结果:AD患者额叶、顶叶、颞叶和胼胝体的FA值与MCI组和对照组均存在显著性差异,MCI患者仅颞叶和胼胝体的FA值与对照组均存在显著性差异。结论:AD患者与MCI患者存在脑白质结构的差异,DTI技术能够在一定程度上提供MCI的早期诊断指标。     

脑出血后继发性神经损伤的弥散加权成像和磁共振频波谱研究

自发性脑内出血(intracerebral hemorrhage，ICH）大约占脑卒中的30％～40％，是引起成人死亡和严重致残的常见原因。ICH的不良预后与很多因素有关，近来认为血肿组织继发性神经损伤(perihematomal secondary neural injury，PSNI)与ICH预后密切相关，对于PSNI产生的机制众说纷纭。     

高血压病合并代谢异常患者脑磁共振波谱及弥散张量成像研究

目的 应用磁共振波谱（Magnetic Resonance Spectroscopy,MRS）及磁共振弥散张量成像（Diffusion Tensor Imaging,DTI）检测病程5年以上高血压病患者的脑内代谢物、脑部各向异性（fractional anisotropy,FA）值,以例早期发现亚临床脑细胞损害.方法 本研究分为病例组（高血压病12例）及对照组（17例健康体检者）,检查一般项目（身高、体重、血压、血糖、血脂、神经功能相关量表评分）,行头颅MRI、DWI、MRS、DTI检查,测定脑部背侧丘脑、扣带回后部、侧脑室后角NAA/Cr、Cho/Cr、NAA/Cho的比值及内囊后肢、放射冠区FA值.结果 （1）病例组NAA/Cr在背侧丘脑、扣带回后部、侧脑室后角均低于对照组（分别t=-2.405、-3.710、-2.068,P＜0.05）;NAA/Cho在扣带回后部、侧脑室后角均低于对照组（分别t=-4.347、3.578,P＜0.01）;Cho/Cr在扣带回后部高于对照组（t=2.965,P＜0.01）;（2）FA值在内囊后肢、放射冠区都明显低于对照组（t=-2.543、P＜0.05;t=-3.394、P＜0.01）.结论 高血压病合并代谢异常且病程5年以上者脑细胞代谢功能及神经纤维微结构已有损害,MRS、DTI检测有助于早期发现亚临床脑细胞损害.     

氢质子磁共振波谱成像技术在创伤性脑损伤后认知障碍中的应用

创伤性脑损伤(TBI)可引起一系列复杂的病理生理过程变化,这些变化包括脑内物质代谢异常,导致机体出现包括头痛、认知、运动和情感障碍等在内的长、短期症状,而认知障碍是阻碍TBI患者日常生活质量恢复和延缓其回归社会的重要因素。氢质子磁共振波谱成像技术(1H-MRS)可对急、慢性脑部损伤患者的脑组织代谢进行非侵入性检测,具有辅助诊断和预测长期功能预后的价值。该文将近年来1H-MRS在TBI后认知障碍中的应用进行总结和展望。[国际神经病学神经外科学杂志, 2021, 48(2):197-201]     

Functional magnetic resonance imaging of mild traumatic brain injury

Functional magnetic resonance imaging (fMRI) offers great promise for elucidating the neuropathology associated with a single or repetitive mild traumatic brain injury (mTBI). The current review discusses the physiological underpinnings of the blood-oxygen level dependent response and how trauma affects the signal. Methodological challenges associated with fMRI data analyses are considered next, followed by a review of current mTBI findings. The majority of evoked studies have examined working memory and attentional functioning, with results suggesting a complex relationship between cognitive load/attentional demand and neuronal activation. Researchers have more recently investigated how brain trauma affects functional connectivity, and the benefits/drawbacks of evoked and functional connectivity studies are also discussed. The review concludes by discussing the major clinical challenges associated with fMRI studies of brain-injured patients, including patient heterogeneity and variations in scan-time post-injury. We conclude that the fMRI signal represents a complex filter through which researchers can measure the physiological correlates of concussive symptoms, an important goal for the burgeoning field of mTBI research.     

Central nervous system microbleeds in the acute phase are associated with structural integrity by DTI one year after mild traumatic brain injury: A longitudinal study

Introduction

Several imaging modalities are under investigation to unravel the pathophysiological mystery of delayed performance deficits in patients after mild traumatic brain injury (mTBI). Although both imaging and neuropsychological studies have been conducted, only few data on longitudinal correlations of diffusion tensor imaging (DTI), susceptibility weighted imaging (SWI) and extensive neuropsychological testing exist.

MR序列优化组合在创伤性脑损伤的诊断价值

目的分析MR诊断创伤性脑损伤(TBI)的价值,探讨TBI患者MR一站式诊断的可行性。方法对260例TBI病例进行MR序列组合扫描,包括小角度激发快速梯度回波序列(FLASH)、流动衰减反转恢复序列(FLAIR)、自旋回波(SE)T1WI、快速自旋回波(TSE)T2WI,比较MR序列组合和CT对各种类型TBI诊断的差异。结果脑实质内出血61例,MR显示61例,CT显示53例;硬膜下出血55例,MR显示55例,CT显示49例;硬膜外出血45例,MR显示45例,CT显示40例;脑挫(裂)伤35例,MR显示35例,CT显示25例;蛛网膜下腔出血35例,MR显示31例,CT显示33例;弥漫性轴索损伤29例,MR显示29例,CT显示5例。MR序列组合准确显示病变256例,CT为209例,两者差异有极显著统计学意义(P0.01),MR序列组合总体诊断敏感性高于CT。结论 MR序列组合(FLASH\FLAIR\T1WI\T2WI)诊断创伤性脑损伤明显优于CT,可列为TBI常规检查方法,实行TBI一站式诊断。     

磁共振波谱分析与外伤性脑损伤研究

磁共振波谱分析是目前唯一的一种活体组织代谢物质无创检测技术,能够即时、动态、客观的反映活体脑组织神经生化代谢情况,为我们进行脑损伤后脑代谢变化研究提供了一种新的手段。本文对磁共振波谱分析原理及在外伤性脑损伤中的应用研究作一简要介绍。     

大鼠轻型颅脑损伤后星形胶质细胞与神经元的病理改变

目的 探讨轻型颅脑损伤（TBI）后神经元及星形胶质细胞改变的病理生理过程。方法 将24只成年SD大鼠随机分为轻型TBI组（n=18）和假手术组（n=6）,轻型TBI组又分为伤后3 h（n=6）、伤后24 h（n=6）、伤后72 h（n=6）三亚组。采用液压冲击法制作轻型TBI模型。采用胶质纤维酸性蛋白（GFAP）染色检测星形胶质细胞,采用Fluoro-Jade B（FJ-B）荧光染色检测变性神经元。结果 与假手术组相比,轻型TBI后3 h、24 h、72 h邻近顶叶皮质、海马CA2/3区GFAP阳性细胞数量均明显减少（P<0.05）;缺失区周围星形胶质细胞肿胀增生明显。FJ-B阳性神经元在损伤后3 h无明显增加（P>0.05）,伤后24 h皮层区FJ-B阳性神经元显著增加（P<0.05）,伤后72 h海马区FJ-B阳性神经元显著增加（P<0.05）。伤后72 h伤侧皮层区与海马区GFAP阳性细胞数和FJ-B阳性细胞数呈显著负相关（r=-0.8285,P<0.05）。结论 轻型TBI后星形胶质细胞超急性期（3 h）即出现损害和胶质反应,神经元则在急性期（24 h）至亚急性期（72 h）出现明显损害,星形胶质细胞缺失程度可以反应神经元损伤程度。     

磁敏感加权成像在轻型颅脑损伤患者中的诊断价值

目的探讨磁共振磁敏感加权成像(SWI)对轻型颅脑损伤(MTBI)患者的诊断价值。方法回顾分析32例MTBI患者(格拉斯哥昏迷量表评分13~15分)的临床资料。患者伤后1周内给予头部CT、MRI及SWI检查,结合CT及相位图排除气体、血管和颅底伪影后,SWI图上的低信号为脑内挫伤出血灶。分别记录MRI常规序列和SWI探查到的病灶数目、发生部位,并结合临床症状进行分析。结果 SWI对脑外伤微小挫伤出血灶检查阳性率明显高于CT及MRI普通序列扫描,特别是在伤后出现晕厥昏迷史或持续性出现临床症状的患者中更为明显。结论 SWI比常规CT及MRI对MTBI患者脑内微小挫伤及出血灶的检出有更高的准确性和客观的诊断价值,并对指导临床治疗及判断预后有重大意义。     

Microstructural basis of contusion expansion in traumatic brain injury: insights from diffusion tensor imaging

Traumatic brain injury (TBI) is often exacerbated by events that lead to secondary brain injury, and represent potentially modifiable causes of mortality and morbidity. Diffusion tensor imaging was used to characterize tissue at-risk in a group of 35 patients scanned at a median of 50 hours after injury. Injury progression was assessed in a subset of 16 patients with two scans. All contusions within the first few days of injury showed a core of restricted diffusion, surrounded by an area of raised apparent diffusion coefficient (ADC). In addition to these two well-defined regions, a thinner rim of reduced ADC was observed surrounding the region of increased ADC in 91% of patients scanned within the first 3 days after injury. In patients who underwent serial imaging, the rim of ADC hypointensity was subsumed into the high ADC region as the contusion enlarged. Overall contusion enlargement tended to be more frequent with early lesions, but its extent was unrelated to the time of initial imaging, initial contusion size, or the presence of hemostatic abnormalities. This rim of hypointensity may characterize a region of microvascular failure resulting in cytotoxic edema, and may represent a ‘traumatic penumbra'' which may be rescued by effective therapy.     

Memory retrieval brain–behavior disconnection in mild traumatic brain injury: A magnetoencephalography and diffusion tensor imaging study

Mild traumatic brain (mTBI) injury is often associated with long‐term cognitive and behavioral complications, including an increased risk of memory impairment. Current research challenges include a lack of cross‐modal convergence regarding the underlying neural–behavioral mechanisms of mTBI, which hinders therapeutics and outcome management for this frequently under‐treated and vulnerable population. We used multi‐modality imaging methods including magnetoencephalography (MEG) and diffusion tensor imaging (DTI) to investigate brain–behavior impairment in mTBI related to working memory. A total of 41 participants were recruited, including 23 patients with a first‐time mTBI imaged within 3 months of injury (all male, age = 29.9, SD = 6.9), and 18 control participants (all male, age = 27.3, SD = 5.3). Whole‐brain statistics revealed spatially concomitant functional–structural disruptions in brain–behavior interactions in working memory in the mTBI group compared with the control group. These disruptions are located in the hippocampal–prefrontal region and, additionally, in the amygdala (measured by MEG neural activation and DTI measures of fractional anisotropy in relation to working memory performance; p < .05, two‐way ANCOVA, nonparametric permutations, corrected). Impaired brain–behavior connections found in the hippocampal–prefrontal and amygdala circuits indicate brain dysregulation of memory, which may leave mTBI patients vulnerable to increased environmental demands exerting memory resources, leading to related cognitive and emotional psychopathologies. The findings yield clinical implications and highlight a need for early rehabilitation after mTBI, including attention‐ and sensory‐based behavioral exercises.