【作者】 祁佩红；

【导师】 史大鹏；

【作者基本信息】 郑州大学 ， 影像医学与核医学， 2010， 硕士

【摘要】 背景和目的：缺血性视神经病变是中老年人较常见的眼科疾病,可造成病人视力明显下降,甚至失明。该病临床诊断困难,临床症状和体征缺乏特异性,CT成像不能显示缺血视神经的形态异常,常规MRI仅能在极少数病例发现异常。因此缺血性视神经病变仍是临床诊断较为困难的疾病之一。弥散张量成像(diffusion tansor imaging, DTI)可早期发现神经纤维的轴突和髓鞘损害,因而在中枢神经系统白质病变的诊断方面显露出广阔的应用前景；基于血氧水平依赖(blood oxygenation level dependent, BOLD)原理的功能磁共振成像(functional magnetic resonance imaging, fMRI)可以反映出脑皮层的功能定位,并可定量分析脑功能区的激活程度和激活范围。故本研究探索应用DTI和fMRI方法研究缺血性视神经病变,旨在发现和评估DTI和fMRI在缺血性视神经病变中的应用价值。材料和方法：研究对象为2008.7-2009.10期间怀疑缺血性视神经病变,共28例,去除实验过程中图像质量不合格的2例,共26例进入实验组,其中男14例,女12例；年龄28～70岁；另选择20例健康成人做对照组。所有研究对象均用SIEMENS Trio Tim 3.0T超导磁共振扫描仪行常规颅脑MRI检查,排除颅内病变后行视神经MRI、DTI、fMRI检查。DTI检查采用单次激发自旋回波平面成像(SE-EPI)序列；后处理在syngo MR B15工作站上进行NEURO 3D后处理,得到视神经各DTI参数值,包括FA、ADC、λ∥、λ⊥、RA、VR值。所有研究对象均行图形视觉诱发电位检查,得到视觉诱发电位潜伏期、振幅的参数值。采用SPSS13.0软件包进行统计分析。视神经DTI和图形视觉诱发电位参数均以x±s表示。用两相关样本的非参数检验对病侧和对侧视神经DTI和图形视觉诱发电位参数进行统计分析。用两独立样本秩和检验对病侧、对侧与对照组视神经DTI和图形视觉诱发电位参数进行统计分析。用spearman相关分析对视觉诱发电位P100、振幅与FA、ADC、λ∥、λ⊥、RA、VR参数进行相关性分析。按α=0.05水准,P<0.05为差异有统计学意义。fMRI数据在MATLAB平台上应用SPM2软件进行数据预处理、统计及结果显示。分析内容包括①对正常对照组左眼、右眼分别进行组分析,获得平均激活图；②对病变组左、右眼分别进行组分析,获得平均激活图；③对病变组与正常对照组左、右眼分别进行组间分析,获得组间比较激活图。结果：一.DTI结果1.病侧视神经FA值和RA值下降,ADC值、λ⊥值、VR值升高,与健侧及对照组视神经DTI各参数值,除λ∥外,组间比较均有统计学差异(P<0.05)。2.病变组健侧与对照组视神经DTI各参数值,组间比较均无统计学差异(P>0.05)。3.患侧ADC值与P-VEP振幅呈明显负相关(rs=-0.63,P<0.05)。λ⊥值与P-VEP振幅呈中等负相关(rs=-0.47,P<0.05)。FA和P-VEP的P100潜伏期呈明显负相关(rs=-0.71,P<0.05)。FA和P-VEP振幅呈弱正相关(rs=0.37,P<0.05)。二、fMRI结果1.正常对照组单眼正常激活最明显的区域为距状沟两侧的初级视皮层区,即Brodmann17区(纹状皮层区),此外舌回、梭状回、楔叶、枕上回、枕中回、枕下回也出现激活,即Brodmann18区和19区(纹旁和纹周区)。另外脑干被盖、上丘,颞上回、颞中回也会出现少量激活。6人外侧膝状体也出现激活。2.左眼缺血性视神经病变组刺激左眼激活图与正常对照组比较：双侧视觉皮层激活区明显减小,右侧视皮层的激活减小的更明显。双侧楔前叶、双侧丘脑、小脑蚓部、左扣带回、胼胝体、左侧海马旁回,脑干中心异常激活。右侧角回、双侧楔叶、双侧颞上回、颞中回激活面积加大。3.右眼缺血性视神经病变组刺激右眼激活图与正常对照组比较：双侧视觉皮层激■活区明显减小,右侧视皮层的激活减小的更明显。右丘脑、右海马旁回、小脑蚓部异常激活,双侧楔叶、双侧颞上回、颞中回激活面积增大。结论：1、DTI可以敏感的检测出缺血性视神经的弥散障碍,为缺血性视神经病变的诊断提供影像学依据。2、DTI参数和视觉诱发电位参数有良好的相关性,两种方法在诊断缺血性视神经病变时可以互补,提高诊断正确率3、正常人视皮层fMRI成像,正常人视觉皮层存在不对称性,多表现为右侧优势,评价视皮层功能活动应注意此种差异。4、刺激患眼,初级视皮层的激活范围及激活程度均明显下降。大脑皮层其它脑区表现出异常激活,说明视皮层存在适应性代偿。更多还原

【Abstract】 Background and purpose Ischemic optic neuropathy is very common optic neuropathy in the middle-aged and old patients, which can cause patients’visual significant decrease, even lose sight. The disease is difficult in clinical diagnosis because clinical symptoms and signs of patients lack specificity. CT imaging has no ability to demenstrate structural changes of ischemic optic neuropathy and conventional MRI examination could only found small part of these cases. Thus ischemic optic neuropathy is also difficult diagnosis according to conventional imaging methods. Diffusion tensor imaging (DTI) could discover earlier injuries of the axon and myelin, so DTI has revealed broad application in the central nervous system disorders. Blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) could reflect the the brain cortex functional status, and can could quantitatively analysis degree and activative scope of brain cortex’s activety. Therefore this research applied DTI and fMRI to study ischemic optic neuropathy in order to discover the application value of DTI and fMRI in anterior ischemic optic neuropathy.Materials and methodsThe subjects were 20 normal persons in control group and 28 patients diagnosed as unilateral anterior ischemic optic neuropathy from July,2008 to October,2009. Two patients were removed because of bad images. Finally, twenty-six patients were in experimental group(14 males,12 females). All subjects were examined with routine brain MRI in order to exclude intracranial diseases using SIEMENS Trio Tim 3.0T superconducting magnetic resonance scanner. Then Then they were underwent with examinations of MRI, DTI and BOLD for optic nerves. DTI examination uses single-shot spin echo planar imaging (SE-EPI) sequence. NEURO 3D post-processing was carried on at Syngo MR B15 workstation and optic nerve’s DTI parameters including the value of the FA, ADC,λ∥,λ⊥, RA, VR were obtained. All subjects underwent pattern reversal visual evoked potentioals (P-VEP) tests and the parameter value (latency and amplitude) of visual evoked potential were obtained. Using the SPSS13.0 software package for statistical analysis, the parameter value of the optic nerve DTI and pattern reversal visual evoked potentioals were recorded as mean±standard deviation. Wilcoxon signed ranks test and Wilcoxon test were used for the group analysis Analysis of correlation was by Spearman’s rank correlation. By a= 0.05 level, P<0.05 has statistics significance.Data preprocessing, statistics, results of the fMRI data were made in the MATLAB platform using SPM2 software. Analysis includes:①To left eye, right eye and of the normal control group employed group analysis respectively and average activation maps were obtained, respectively.②To left eye and right eye of the patients group employed group analysis and the average activation maps were obtained, respectively.③To left eye and right eye of the patients group and normal group respectively used the group analysis and the differences between activation maps of the two groups were obtained.ResultsDTI Results1. Diseased optic nerve’s FA value and RA value decreased, ADC value,λ⊥value,VR value increased. DTI parameter values butλ∥between the optic nerve’s diseased side and the healthy side in patient group.2. There were not statistically significant differences (P>0.05) in all of DTI parameter values of optic nerves between the patient group heathy side and the control group.3. The dseased optic nerve ADC correlated with P-VEP amplitude (rs=-0.63, P <0.05). The dseased optic nerveλ⊥correlated with P-VEP amplitude (rs=-0.47, P <0.05).). The dseased optic nerve FA correlated with both P-VEP whole-field latency (rs=-0.71, P<0.05) and P-VEP whole-field amplitude (rs=0.37, P<0.05).fMRI relults1. In the normal group, the most obvious activation areas of the single eye and bilateral eyes are both sides’s primary visual cortex of the calcarine sulcus, that is Brodmann17 area (striate cortex), as well as lingual gyrus, fusiform gyrus, cuneate lobe, superior occipital gyrus, middle occipital gyrus, inferior occipital gyrus presented the activation, which is at Brodmann18 area and 19 (besides and around of striate cortex). Moreover the brain stem tegmentum, anterior colliculi, superior temporal gyrus and middle temporal gyrus (Brodmann22) also presented few activation areas. Some patients’s lateral geniculate also appeared activated.2. Compared stimulating the left eye’s activation maps of ischemic optic neuropathy group and the normal control group showed bilateral visual cortex activated area decreased significantly, the right side visual cortex activation area reduced more obviously. Bilateral precuneus, bilateral cerebral ganglion, cerebellar vermis, left cingulate gyrus, corpus callosum, left Subiculum hippocampi and brain sterm center appeared abnormal activation. The activation area became large in the right angular gyrus, bilateral cuneate lobe, bilateral superior temporal gyrus, middle temporal gyrus.3. Comparing stimulating the right eye’s activation maps of ischemic optic neuropathy group and the normal control group showed bilateral visual cortex activated areas decreased significantly, the right side visual cortex activation area reduced more obviously; the right cerebral ganglion, right subiculum hippocampi and cerebellar vermis appeared abnormal activation;the activation area became large in the bilateral cuneate lobe, bilateral superior temporal gyrus and middle temporal gyrus.Conclusion1. DTI can sensitively detect the diffusion disorder of ischemic optic nerves. It may provide imaging evidences for ischemic optic nerves.2. DTI parameters and visual evoked potential parameters have favourable correlation. The two methods can complement when diagnosing ischemic optic neuropathy.3. Normal person’s visual cortex exists asymmetry, the right side has obvious superiority.4. Stimulating the ischemic side, the activation area and activation degree of visual cortex significantly decreased. The other cerebral cortexs was abnormally activatedthat may explain the visual cortex’s adaptability reconstitution.更多还原