首页 > 文献资料
-
慢性酒精依赖性脑病的功能磁共振研究进展
目前,国内临床上对慢性酒精依赖者脑病(Chronic Alcohol Dependence Encephalopathy,CADE)的评估主要是依据中国精神疾病分类和诊断标准,缺乏客观量化指标.随着MRI技术的日趋成熟,特别是功能性MRI的飞速发展,动脉血质子自旋标记(arterial spin labeling,ASL)、磁共振弥散张量成像(magnetic resonance diffusion tensor imaging,DTI)、磁共振脑功能成像(functional magnetic resonance imaging,fMRI)及磁共振波谱(magnetic resonance spectroscope,MRS)在慢性酒精依赖性脑病的研究已逐渐展开,为CADE的病因、发病机理及疗效观察提供了新的研究手段,期望对慢性酒精依赖性脑病的量化诊断起到一定作用.
-
Fractional anisotropy values in diffusion tensor imaging can quantitatively relfect the consistency of nerve ifbers after brain damage, where higher values generally indicate less damage to nerve ifbers. Therefore, we hypothesized that diffusion tensor imaging could be used to evaluate the effect of mild hypothermia on diffuse axonal injury. A total of 102 patients with diffuse axonal injury were randomly divided into two groups:normothermic and mild hypothermic treatment groups. Patient’s modiifed Rankin scale scores 2 months after mild hypothermia were signiifcant-ly lower than those for the normothermia group. The difference in average fractional anisotropy value for each region of interest before and after mild hypothermia was 1.32-1.36 times higher than the value in the normothermia group. Quantitative assessment of diffusion tensor imaging indicates that mild hypothermia therapy may be beneifcial for patients with diffuse axonal injury.
-
To attain the volumetric information of the optic radiation in normal human brains, we per-formed diffusion tensor imaging examination in 13 healthy volunteers. Simultaneously, we used a brain normalization method to reduce individual brain variation and increase the accuracy of volumetric information analysis. In addition, tractography-based group mapping method was also used to investigate the probability and distribution of the optic radiation pathways. Our results showed that the measured optic radiation ifber tract volume was a range of about 0.16%and that the fractional anisotropy value was about 0.53. Moreover, the optic radiation probability ifber pathway that was determined with diffusion tensor tractography-based group mapping was able to detect the location relatively accurately. We believe that our methods and results are help-ful in the study of optic radiation ifber tract information.
-
Temporal lobe resection is an important treatment option for epilepsy that involves removal of potentially essential brain regions. Selective amygdalohippocampectomy is a widely performed temporal lobe surgery. We suggest starting the incision for selective amygdalohippocampec-tomy at the inferior temporal gyrus based on diffusion magnetic resonance imaging (MRI) tractography. Diffusion MRI data from 20 normal participants were obtained from Parkinson’s Progression Markers Initiative (PPMI) database (www.ppmi-info.org). A tractography algorithm was applied to extract neuronal fiber information for the temporal lobe, hippocampus, and amygdala. Fiber information was analyzed in terms of the number of fibers and betweenness centrality. Distances between starting incisions and surgical target regions were also considered to explore the length of the surgical path. Middle temporal and superior temporal gyrus regions have higher connectivity values than the inferior temporal gyrus and thus are not good candi-dates for starting the incision. The distances between inferior temporal gyrus and surgical target regions were shorter than those between middle temporal gyrus and target regions. Thus, the in-ferior temporal gyrus is a good candidate for starting the incision. Starting the incision from the inferior temporal gyrus would spare the important (in terms of betweenness centrality values) middle region and shorten the distance to the target regions of the hippocampus and amygdala.
-
Psychosis is a common non-motor symptom of Parkinson’s disease whose pathogenesis remains poorly understood. Parkinson’s disease in conjunction with psychosis has been shown to induce injury to extracorticospinal tracts as wel as within some cortical areas. In this study, Parkinson’s disease patients with psychosis who did not receive antipsychotic treatment and those without psychosis underwent diffusion tensor imaging. Results revealed that in Parkinson’s disease patients with psychosis, damage to the left frontal lobe, bilateral occipital lobe, left cingulated gyrus, and left hippocampal white-matter fibers were greater than damage to the substantia nigra or the globus pal idus. Damage to white-matter fibers in the right frontal lobe and right cingulate gyrus were also more severe than in the globus pal idus, but not the substantia nigra. Damage to frontal lobe and cingulate gyrus white-matter fibers was more apparent than that to occipital or hippocampal fiber damage. Compared with Parkinson’s disease patients without psychosis, those with psychosis had significantly lower fractional anisotropy ratios of left frontal lobe, bilateral occipital lobe, left cingu-lated gyrus, and left hippocampus to ipsilateral substantia nigra or globus pal idus, indicating more severe damage to white-matter fibers. These results suggest that psychosis associated with Par-kinson’s disease is probably associated with an imbalance in the ratio of white-matter fibers be-tween brain regions associated with psychiatric symptoms (frontal lobe, occipital lobe, cingulate gyrus, and hippocampus) and those associated with the motor symptoms of Parkinson’s disease (the substantia nigra and globus pal idus). The relatively greater damage to white-matter fibers in psychiatric symptom-related brain regions than in extracorticospinal tracts might explain why psy-chosis often occurs in Parkinson’s disease patients.
-
The brain is highly plastic after stroke or epilepsy;however, there is a paucity of brain plasticity investigation after traumatic brain injury (TBI). This mini review summarizes the most recent evidence of brain plasticity in human TBI patients from the perspective of advanced magnetic resonance imaging. Similar to other forms of acquired brain injury, TBI patients also demonstrat-ed both structural reorganization as well as functional compensation by the recruitment of other brain regions. However, the large scale brain network alterations after TBI are still unknown, and the ifeld is still short of proper means on how to guide the choice of TBI rehabilitation or treat-ment plan to promote brain plasticity. The authors also point out the new direction of brain plas-ticity investigation.
-
Magnetic resonance diffusion tensor imaging has been shown to quantitatively measure the early pathological changes in chronic cervical spondylotic myelopathy. In this study, a novel spongy pol-yurethane material was implanted in the rat C 3-5 epidural space to establish a rat model of chronic cervical spondylotic myelopathy. Diffusion tensor data were used to predict pathological changes. Results revealed that the fractional anisotropy value gradual y decreased at 4, 24, and 72 hours and 1 week after injury in rat spinal cord, showing a time-dependent manner. Average diffusion coeffi-cient increased at 72 hours and 1 week after implantation. Hematoxylin-eosin staining and Luxol-fast-blue staining exhibited that the number of neurons in the anterior horn of the spinal cord gray matter and the nerve fiber density of the white matter gradual y reduced with prolonged com-pression time. Neuronal loss was most significant at 1 week after injury. Results verified that the fractional anisotropy value and average diffusion coefficient reflected the degree of pathological change in the site of compression in rat models at various time points after chronic spinal cord compression injury, which potential y has a reference value in the early diagnosis of chronic cervical spondylotic myelopathy.
-
Diffusion tensor imaging was performed in 105 volunteers free of central nervous system lesions.No differences were found in fractional anisotropy between the left and right cerebral peduncles among subjects (P > 0.05). The lower limit value of fractional anisotropy was 0.36, and the asymmetry ratio was 0.77. The area and lower limit value of the cerebral peduncles were 0.90 cm2and 0.83, respectively. These results will be useful in evaluating the diagnosis of Wallerian degeneration following cerebral infarction.
-
MR扩散张量成像在骨骼肌肉系统中的研究进展
DTI作为目前惟一可以评价活体组织各向异性扩散情况的技术,广泛应用于神经系统的研究,其临床应用价值已经得到充分肯定[1].随着研究的拓展,DTI已被应用于骨骼肌肉系统的研究[2-8],初步研究结果表明其有着巨大潜在应用前景.笔者就DTI在骨骼肌肉系统中的研究进展予以综述.
-
酒精成瘾磁共振成像研究进展
酒精成瘾是一种以失去控制地应用酒精为特征的慢性脑疾病.WHO估计全世界大约有1.4亿酒精成瘾者,且酒精的过量服用是导致15~59岁男性死亡的首要危险因素[1].近年来,随着我国经济的发展,饮酒人口的增加,酒精滥用与成瘾已成为我国日益严重的公共卫生问题.磁共振成像技术能够无创地观察大脑宏观体积、微观纤维束、代谢及接受各种刺激时神经活动水平的变化,近年来该类成像技术已被广泛用于酒精滥用和成瘾研究.目前被应用于酒精成瘾研究的磁共振成像技术主要有:结构磁共振成像(structral magnetic resonance imaging,sMRI)、磁共振弥散张量成像(magnetic resonance diffusion tensor imaging,DTI)、磁共振波谱(magnetic resonance spectroscopy,MRS)及功能磁共振成像(functional magnetic resonance imaging,fMRI).
-
扩散张量成像在脑白质病诊断中的应用
扩散张量成像(diffusion tensor imaging,DTI)以其对于方向的敏感性在脑白质纤维束成像方面发挥了非常重要的作用,该技术为研究脑发育、脑认知功能、脑疾病的病理变化以及脑部手术的术前计划和术后评估提供了强有力的工具,使得以上工作的量化成为可能,为循证医学在影像学的深入发展提供了确实可行的途径.现就DTI在脑白质病的诊断、治疗、评诂方面综述如下.
-
扩散张量成像在乳腺良恶性病变鉴别中的临床研究
乳腺癌是女性常见的恶性肿瘤之一,其发病率逐年上升,平均年增长率为2%~3%。在我国大城市乳腺癌已占女性恶性肿瘤患病率第1位,严重影响到女性生活质量[1]。据临床资料显示,早期乳腺癌的5年生存率为90%以上。因此,乳腺癌的早期发现、早期诊断和早期治疗是降低其死亡率的关键。扩散张量成像(diffusion tensor imaging,DTI)作为新型的检查手段,无创伤、无辐射,不仅可以测定病变的扩散能力,同时还能测定各向异性,用于评估良恶性不失为一种快速易行可重复的方法,在诊断和鉴别诊断乳腺良恶性病变中具有潜在独特的应用价值。本研究回顾性分析乳腺良恶性病灶与患、健侧腺体表观扩散系数(apparent diffusion coefficient,ADC)和部分各向异性(fractional anistropy,FA)的差异,旨在探讨 DTI 鉴别乳腺良恶性病变的价值,对临床把握治疗时机及手术方式提供指导。