大鼠脑出血多模态磁共振成像的动态观察

发布时间：2018-08-14 09:25

【摘要】：背景和目的脑血管病是严重危害人类健康的三大主要疾病之一，流行病学调查资料显示，脑出血（intracerebral hemorrhage, ICH）的发病率、死亡率、致残率极高，严重威胁着人们的健康和生活。脑出血最重要的病理改变是血肿本身和血肿周围的继发性损伤，如何应用影像学检查方法，在脑出血的早期及时做出准确的诊断，并评估血肿周围脑组织的继发性改变，对脑出血的诊断、治疗和预后评估具有重要的意义。传统的观点认为，脑出血的首选检查手段是CT，常规磁共振成像（magneticresonance imaging, MRI）对出血不敏感。近年来，随着MRI设备的不断更新与磁共振成像新技术的发展，如多回波采集的T2*WI三维梯度回波（enhanced T2starweighted angiography, ESWAN）、扩散加权成像（diffusion weighted imaging,DWI）、灌注加权成像（perfusion weighted imaging, PWI）、磁共振波谱成像（magnetic resonance spectroscopic imaging, MRSI）、扩散张量成像（diffusiontensor imaging, DTI）在脑出血的研究中已得到广泛的应用。其中ESWAN序列是近年来新兴起的MRI检查技术，它对磁敏感性物质尤其敏感，不仅可以及早的发现出血灶，还能检出常规序列所不能发现的微出血灶，对临床治疗方式的选择具有重要的参考价值。本实验的研究目的是通过MRI检查，探讨脑出血后血肿体积的演变与灶周水肿的变化情况，并与病理结果对照，分析影像资料与病理指标的相关性。材料与方法 1.随机选取清洁级健康雄性SD大鼠64只，体重250g~300g，平均(280.3±7.5) g。实验动物均由河南省动物实验中心提供。按照随机数字表法将大鼠分为实验组和对照组，实验组48只，行开颅、钻孔、进针并注血，对照组16只，除不注血外其他操作同实验组。以上动物均于造模后1h、3h、12h、24h、48h、72h、1w、2w分别行MRI扫描，并于各个时间点取病理标本。 2.脑出血模型的制作过程：将大鼠固定于立体定位仪上，取前囟后0.3mm，向左旁开3mm处，采用颅骨钻钻一大小约1mm直径的小孔，进针6mm。取自体左心室动脉血40ul注入（3分钟内），留针10分钟后拔出，封闭骨孔，缝合，行MRI扫描。 3.磁共振扫描采用美国GE公司7503.0T超导高场磁共振扫描机和大鼠专用线圈。实验组和对照组分别于造模后1h、3h、12h、24h、48h、72h、1w、2w行T1加权成像（T1-weighted imaging, T1WI）、T2加权成像（T2-weighted imaging,T2WI）、扩散加权成像（diffusion weighted imaging, DWI）、T2*WI及ESWAN序列扫描。根据磁共振扫描相应层面，，在各个时间点分别选取2只大鼠，断头取脑，进行干湿重分析和免疫组织化学MMP9、AQP4的半定量分析。 4.观察不同时间点大鼠脑出血在ESWAN序列上相位弧度值、SWAN信号值的动态演变。经图像后处理测出血肿在T2WI、T2*WI、ESWAN序列上的体积，并与大体标本所测得体积进行比较，得出以上各个序列的放大率。观察比较不同时间点大鼠出血灶灶周DWI图像的变化情况，并记录表观扩散系数（apparentdiffusion coefficient, ADC）的变化。MRI检查后取脑组织行脑组织含水量测量，并取脑组织切片观察MMP9和AQP4的表达趋势，分析ADC值、脑组织含水量与MMP9、AQP4的相关性。 5.所得结果使用SPSS17.0统计软件包行统计学分析，计量结果使用均数±标准差表示。运用的统计学方法是独立样本的t检验、配对样本的t检验、方差分析、相关性分析，以P0.05为检验水准。结果 1.实验组大鼠脑出血后，出血中心区域相位弧度值、SWAN信号值均降低。实验组大鼠与对照组大鼠不同时间点相位弧度值、SWAN信号值对比，差异有统计学意义（P＜0.05）；实验组大鼠出血侧与镜像侧相位弧度值、SWAN信号值对比，差异有统计学意义（P＜0.05）。 2. T2WI、T2*WI、ESWAN序列及大体标本所测血肿体积显示，血肿体积在1h~2w时间段均逐渐减小。其中，T2WI所测血肿体积与大体标本所得体积比较，无显著性差异（P=0.125＞0.05），T2*WI、ESWAN序列所测血肿体积与大体标本所得体积比较，差异有统计学意义（P=0.025＜0.05）。即T2WI对血肿体积的显示较确切，ESWAN、T2*WI序列对血肿的显示均存在放大效应，平均放大率分别为1.707±0.086,1.332±0.050。 3.实验组大鼠血肿周围的脑组织在1h时ADC值无明显变化，3~72h ADC值上升。实验组大鼠与对照组大鼠各个时间点ADC值相比，除1h、7d、14d组外，差异均有统计学意义（P＜0.05）；实验组大鼠各个时间点出血侧ADC值与镜像侧相比，除1h、7d、14d组外，差异均有统计学意义（P＜0.05）。 4.实验组大鼠MMP9在出血后3h即可见表达，24h明显增多，48h达高峰，出血14天时仍有表达。除了1h外，实验组大鼠与对照组大鼠各个时间点的IODMMP9比较，差异均有统计学意义（P＜0.05）。 5.实验组大鼠AQP4在出血后1h可见阳性表达，12h表达增强，48h达高峰，14d仍可见表达。实验组大鼠与对照组大鼠各个时间点IODAQP4的比较，差异均有统计学意义（P＜0.05）。 6.分析ADC值、干湿重结果与病理指标MMP9、AQP4的相关性，ADC值与MMP9呈正相关性，脑组织含水量与MMP9、AQP4也存在正相关性。结论 1. ESWAN序列可以准确的识别出血灶，并且可以用于早期出血的检查 2. ESWAN、T2*WI序列对血肿的显示存在放大效应，而T2WI对血肿的显示更接近于真实大小 3.大鼠脑出血后血肿周围AQP4和MMP9的表达随着时间的延长，呈逐步增加的趋势
[Abstract]:Background and purpose
Cerebrovascular disease is one of the three major diseases that seriously endanger human health. Epidemiological investigation data show that the incidence, mortality and disability rate of intracerebral hemorrhage (ICH) are extremely high, which seriously threaten people's health and life. How to make an accurate diagnosis in the early stage of intracerebral hemorrhage and evaluate the secondary changes of brain tissue around the hematoma by imaging examination is of great significance to the diagnosis, treatment and prognosis evaluation of intracerebral hemorrhage.
In recent years, with the continuous updating of MRI equipment and the development of new MRI techniques, such as enhanced T2 * WI three-dimensional gradient angiography (ESWAN) with multi-echo acquisition, expanding. Diffusion weighted imaging (DWI), perfusion weighted imaging (PWI), magnetic resonance spectroscopic imaging (MRSI), diffusion tensor imaging (DTI) have been widely used in the study of cerebral hemorrhage. The rising MRI technology is particularly sensitive to magnetic sensitive substances. It can not only detect hemorrhagic foci early, but also detect micro-hemorrhagic foci which can not be found by conventional sequence. It has important reference value for the choice of clinical treatment.
The purpose of this study is to investigate the changes of hematoma volume and perifocal edema after intracerebral hemorrhage by MRI, and to compare with pathological results, and to analyze the correlation between imaging data and pathological indicators.
Materials and methods
1. Sixty-four healthy male SD rats of clean grade were randomly selected, weighing 250-300 g, with an average of (280.3 (+ 7.5) g. The experimental animals were provided by Henan Provincial Animal Experimental Center. According to the random number table method, the rats were divided into experimental group and control group. 48 rats in the experimental group were craniotomy, drilling, needling and blood injection. 16 rats in the control group were operated in the same way except without blood injection. All the above animals were scanned by MRI at 1h, 3h, 12h, 24h, 48h, 72h, 1W and 2W after modeling, and pathological specimens were taken at each time point.
2. The process of making cerebral hemorrhage model: Fixed the rat on the stereotactic positioner, 0.3 mm after the anterior fontanel, 3 mm to the left side, drilled a small hole about 1 mm in diameter with a skull drill, and needled 6 mm. The left ventricular artery blood 40 UL was injected (within 3 minutes), the needle was pulled out after 10 minutes, the bone hole was closed, sutured and MRI scanned.
3. Magnetic resonance scans were performed with 7503.0T superconducting high-field magnetic resonance scanner made by GE Company and special coils for rats. The experimental group and the control group were performed T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion weighted imaging (DWI) at 1 h, 3 h, 12 h, 24 h, 48 h, 72 h, 1 W and 2 W after modeling, respectively. Two rats were selected at each time point and their brains were cut off for dry-wet weight analysis and semi-quantitative analysis of immunohistochemical MMP9 and AQP4.
4. To observe the dynamic changes of phase radian and SWAN signal value of intracerebral hemorrhage on ESWAN sequence at different time points. The volume of hemorrhage on T2WI, T2*WI and ESWAN sequence was measured by image post-processing, and the magnification of each sequence was obtained by comparing with the volume measured by gross specimen. The changes of DWI images were recorded and the apparent diffusion coefficient (ADC) was recorded. After MRI examination, the water content of brain tissues was measured. The expression trend of MMP9 and AQP4 was observed and the correlation between ADC value, water content of brain tissues and MMP9 and AQP4 was analyzed.
5. The results were analyzed by SPSS17.0 statistical software package, and the measurement results were expressed by mean-standard deviation.
Result
1. After intracerebral hemorrhage, the phase radian and SWAN signal value of the hemorrhagic center decreased. The phase radian and SWAN signal value of the experimental group and the control group at different time points were significantly different (P < 0.05); the phase radian and SWAN signal value of the hemorrhagic side and the mirror side of the experimental group were significantly different (P < 0.05). Significance (P < 0.05).
2. The hematoma volume measured by T2WI, T2 * WI, ESWAN sequence and gross specimen showed that the hematoma volume decreased gradually in the period of 1 h to 2 w. There was no significant difference between the hematoma volume measured by T2WI and that obtained by the general specimen (P = 0.125 > 0.05), the hematoma volume measured by T2 * WI, ESWAN sequence and the volume obtained by the general specimen, the difference was statistically significant. Meaning (P = 0.025 < 0.05). T2WI showed the hematoma volume more accurately. Both ESWAN and T2 * WI showed magnification effects on hematoma. The average magnification rates were 1.707 (+ 0.086) and 1.332 (+ 0.050) respectively.
3. The ADC value of the brain tissue around the hematoma in the experimental group did not change significantly at 1 hour, but increased at 3-72 hours. The ADC value of the experimental group was significantly different from that of the control group at each time point except 1 hour, 7 days and 14 days (P < 0.05); the ADC value of the hemorrhagic side of the experimental group was significantly different from that of the mirror side at each time point except 1 hour, 7 days and 14 days. There was statistical significance (P < 0.05).
4. The expression of MMP-9 was observed at 3 hours after bleeding, increased significantly at 24 hours, reached the peak at 48 hours, and still expressed at 14 days after bleeding in the experimental group. Except for 1 hour, the difference between the experimental group and the control group was statistically significant (P < 0.05).
5. AQP4 positive expression was observed at 1 hour after bleeding, increased at 12 hours, peaked at 48 hours, and still expressed at 14 days in the experimental group and the control group. The difference was statistically significant (P < 0.05).
6. The ADC value, the results of dry and wet weight were correlated with pathological indexes MMP9 and AQP4, ADC value was positively correlated with MMP9, and brain water content was positively correlated with MMP9 and AQP4.
conclusion
1. ESWAN sequence can accurately identify bleeding foci, and can be used for early bleeding examination.
2. ESWAN and T2*WI sequences have magnification effect on the display of hematoma, while T2WI is closer to the real size of hematoma.
3. the expression of AQP4 and MMP9 around hematoma after cerebral hemorrhage in rats showed a trend of gradual increase with the extension of time.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R743.34;R445.2

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