【作者】 王琪；

【导师】 马翔；

【作者基本信息】 大连医科大学 ， 眼科学， 2010， 硕士

【摘要】 目的：通过应用锰离子增强磁共振扫描(MEMRI)对正常和视神经损伤大鼠的视觉传导通路进行观察,从而评价锰离子增强磁共振扫描在正常或视神经损伤大鼠的应用价值,以期对正常视神经传导通路显影或能够早期发现视觉传导通路病变的部位,寻找到一种新的影像学诊断方法。方法：健康成年SD大鼠16只随机分为3组：1)剂量相关性研究大鼠6只：大鼠右眼玻璃体腔分别注射10nmol、50nmol、200nmol、300nmol、500nmol Mn2+,24h后进行MRI扫描,以视神经为研究对象,测得不同剂量条件下MRI图像中右眼视神经的平均信号强度和相对应左眼未被强化视神经的平均信号强度,同时计算不同剂量条件下对应的视神经的对比信噪比(CNR)。以Mn2+总量为横坐标,CNR值为纵坐标绘制剂量相关曲线,进行不同Mn2+剂量磁共振扫描与MRI信号强度之间的相关性分析。2)实验对照研究大鼠5只：以右侧视觉传导通路为实验组,以左侧视觉传导通路为对照组,向正常大鼠右眼玻璃体腔注射300nmol Mn2+,24h后进行MRI扫描,测量双侧视网膜、视神经、视交叉、视束、外侧膝状体和上丘的平均信号强度并计算信噪比(SNR),比较被Mn2+强化的右侧视觉传导通路和未被强化的左侧相对应的部位,采用配对t检验进行统计学分析。3)视神经损伤与非损伤对比研究大鼠5只：制作成年SD大鼠右眼视神经机械性损伤模型,在视神经损伤大鼠右眼玻璃体腔内注射300nmolMn2+,24h后进行MRI扫描,分别记录视神经损伤侧与未损伤侧视觉传导通路MRI图像,并与第2组图像相关数据比较,计算SNR,分别测量机械性视神经损伤侧的大鼠视网膜、损伤前视神经、损伤后视神经、和上丘的MRI平均信号强度和对侧正常相对应部位的MRI平均信号强度,研究视神经损伤后MRI图像中信号强度的变化,采用方差分析进行统计学分析。结果：1.剂量相关性实验中剂量与CNR值的统计学分析玻璃体腔内注射Mn2+量与CNR值呈曲线相关,绘制相关曲线,经统计学计算P=0.026(P<0.05),r=0.865,呈高度正相关关系。即Mn2+剂量越大,MRI图像的强化程度越高。2.在对照实验研究中,对视网膜、视神经、视交叉、视束、外侧膝状体、上丘各部位图像进行统计学分析右眼玻璃体腔内注射Mn2+后,该侧对应的视网膜、视神经、视交叉视束、外侧膝状体、上丘各部位MEMRI图像上的SNR值相对未强化的左侧显著增加,玻璃体腔注射300nmol Mn2+后MRI图像显著强化。3.视神经损伤实验研究中的统计学分析从视网膜到视神经损伤处之间的MRI图像强化显著,损伤远端的视觉传导通路各部位未见强化。结论：1. MEMRI可清晰、准确的显示大鼠视觉传导通路。2.玻璃体腔注射Mn2+剂量越大,MEMRI图像中视觉传导通路的强化程度越显著。3.由于视神经轴突受损,Mn2+积聚于视神经损伤部位,MEMRI图像上呈高信号,可显示损伤部位,对外伤性视神经损伤的确诊可提供更有利的依据。更多还原

【Abstract】 Objective:Using manganese-enhanced magnetic resonance imaging to observe the visual pathway of normal and optic nerve injury rats. Evaluate the value of manganese-enhanced magnetic resonance imaging. Normal visual pathway were visualized and the sites of the optic nerve injury were early detected. Find out a new image diagnosis of visual pathway.Methods:Healthy adult SD rats (N=16) were divided into 3 groups at random.1) Dose-response experiment (N=6):MRI was performed 24 hours after right eyes intravitreal MnCl2 injection. The dose were 10nmol、50nmol、200nmol、300nmol and 500nmol respectively. In order to study the optic nerve, the average signal intensity of the right and the left optic nerve in MRI images were measured under different doses. The contrast-to-noise ratio (CNR) of the optic nerve was calculated. Draw a dose-response curve of Mn2+ to analyze the correlation between different doses (Abscissa is the total amount of Mn2+, vertical axis is the CNR values).2) Experimental-control experiment (N=5):Right eye was the experimental group; left eye was the control group. MRI was performed 24 hours after right eyes intravitreal MnCl2 injection. The dose was 300nmol. The average signal intensity was measured (bilateral retina, optic nerve, optic chiasm, optic tract, lateral geniculate body and superior colliculus) and SNR was calculated. The enhancement in the visual pathway was compared. Paired t test was used for statistical analysis.3) Comparison of optic nerve injury and non-injury experiment (N=5):First, produced mechanical injury model on right optic nerve of adult SD rats. MRI was performed 24 hours after right eyes intravitreal MnCl2 injection. The doses were 300nmol. Recording MRI images of the visual pathway of optic nerve injury side and the other side. Compare with the data of control group and calculate SNR. The average signal intensity in MRI images of both visual pathways was measured. The changes of signal intensity in optic nerve injury rats were studied. Variance to analyze was used to analyze of the date.Results:1. The relationship between the dose and CNR in dose-response experimentThe relationship between the dose and CNR is curvilinear correlation (P=0.026, r=0.865). There are strong positive correlation between the dose and CNR. Showing that the higher dose of Mn2+, the higher degree of enhancement of MRI images.2. Comparison of the images in both sides of the visual path waysAfter right eye intravitreal Mn2+ injection, SNR of right visual patyway (include retina, optic nerve, optic chiasm, optic tract, lateral geniculate body, superior colliculus) are higher than the other side in MEMRI. After intravitreal 300 nmol Mn2+ injection the MRI images was significantly enhanced.3. Statistical analysis of the optic nerve injuryThe MRI images from the retina to the optic nerve injury site were significantly enhanced. The remote parts of the injured optic nerve were not enhanced.Conclusion:1. MEMRI can be clear, accurate display of the visual pathway in rats.2. The higher dose of Mn2+ injected into the vitreous, the higher degree of enhancement of MRI images.3. Mn2+ accumulated in the optic nerve injury site, because damage to the optic nerve axons. The high signal intensity was showed of the injured site in MEMRI images. It is more conducive to diagnosis of traumatic optic nerve injury.更多还原