光相干断层成像研究血液中生物大分子引起的光学性质变化

发布时间：2019-01-08 10:02

【摘要】：纤维蛋白原（Fibrinogen）作为血浆中一种重要的凝血蛋白，在血液凝固过程中发挥着重要的作用，并与红细胞聚集的发生有关。现有的临床诊断中，对血液中Fg含量的方法学检验主要建立在物理化学法、免疫法及光学法的基础上。然而，抽取病人血样后对血液的检测，不能实时准确的反应血液中的各项参数，同时还会增加病人的痛苦及感染的风险。近年来发展出的一种新型医学成像技术，光相干断层成像技术（optical coherence tomography, OCT）能够实现对生物组织的无创、实时、在体的成像检测。类似于纤维蛋白原在血液中的作用，葡聚糖（Dextran）作为一种外源性的生物大分子，同样可以引起血液中红细胞的聚集，从而引发血液光学性质的改变。因此，本论文通过研究葡聚糖对血液光学性质的改变，摸索出合理的OCT检测条件及参数，进而考察利用OCT技术检测血液中纤维蛋白原含量的可行性。主要结果如下： 1．首先利用外源性的生物大分子葡聚糖研究其不同浓度对血液光学性质的影响，确定了两个光学参数—OCT深度分辨的背向散射光信号斜率（OCTSS）及探测光到达血液容器底部的反射强度R。研究发现葡聚糖的加入提高了血液中红细胞的胞液与血浆间的折射率系数匹配，同时还会引发红细胞的聚集。这两方面的效应使得血液对光的散射面积减小，光散射作用变弱。表现为OCTSS随血液葡聚糖浓度升高而减小，底部光反射强度R增大。但当葡聚糖浓度超过一定值后，会导致红细胞的分散，使得血液光散射变强，，OCTSS及R均表现为相反的变化趋势。另外，随血细胞压积（Hematocrit，HCT）的升高，血液中红细胞比重上升，散射颗粒增多，血液光散射增强，表现为OCTSS增大，R下降。 2．利用OCT考察了不含纤维蛋白原的血液在不同葡聚糖浓度下的光学性质变化，以此确定最优的分离血浆纤维蛋白原的方法。实验发现，利用化学沉淀法（冷乙醇法及硫酸铵法）处理后的血液，其OCTSS随着葡聚糖浓度的升高出现异常变化。而冻融法处理后的血液，其光学参数随着葡聚糖浓度呈现正常的变化趋势。因此，最优去除血浆纤维蛋白原的方法为冻融法。 3．血浆经最优方法除去其自身纤维蛋白原后，利用外源的人血浆纤维蛋白原干粉定量配制不同浓度的血浆，然后研究不同纤维蛋白原浓度的血液中光学性质的变化。实验发现，由于纤维蛋白原干粉对猪血红细胞较弱的聚集作用，其血液OCTSS及R都没有随纤维蛋白原浓度的升高出现显著变化。而在人血中的实验则发现，OCTSS随Fg浓度升高呈现显著减小的趋势，当血浆纤维蛋白原浓度超过人体正常范围（2-4g/L）后，OCTSS值减弱到相当低的程度，表现出对血液高危险Fg水平很强的识别能力。而底部反射峰R则由于所用仪器及实验材料的影响不能有效反应血浆中纤维蛋白原的水平。此外，血液其他因素如血细胞压积、血液流速、细胞自身因素（cell-specific factors）等都对OCTSS的变化有一定程度的影响。总的来说，光相干断层成像作为一种新型的无损检测技术，通过发展同时检测其他血液性质的方法及合理的校准手段消除其他因素的影响，可期望发展成为一种理想的检测血液纤维蛋白原含量的新手段。
[Abstract]:Fibrinogen is an important blood coagulation protein in plasma, plays an important role in the process of blood coagulation, and is related to the occurrence of red blood cell aggregation. In the present clinical diagnosis, the method for the determination of the content of Fg in the blood is mainly based on the physical and chemical method, the immune method and the optical method. However, the detection of blood after a patient's blood sample is taken, the parameters in the blood can not be accurately reflected in real time, and the pain and the infection risk of the patient are also increased. In recent years, a new type of medical imaging technology, optical coherence tomography (OCT), can be used to detect the non-invasive, real-time and in-vivo imaging of biological tissue. Like the role of fibrinogen in the blood, dextran acts as an exogenous biological macromolecule, which can also cause the aggregation of red blood cells in the blood, leading to a change in the optical properties of the blood. Therefore, through the study of the changes of the optical properties of the dextran to the blood, the reasonable OCT conditions and parameters were found, and the feasibility of using the OCT technique to detect the content of fibrinogen in the blood was also investigated. The main results are as follows: 1. First, the effect of different concentrations on the optical properties of blood was studied by using exogenous biological macromolecular dextran. In response, two optical parameters, the OCT depth-resolved back-scattered-light signal slope (OCTSS), and the reflected intensity R of the probe light at the bottom of the blood vessel were determined. The study found that the addition of the glucan increased the refractive index of the erythrocyte in the blood and the plasma. It can also cause the aggregation of red blood cells. the effects of these two aspects are such that the scattering area of the blood is reduced, the light-scattering effect changes, Weak. The expression of OCTSS decreased with the increase of the blood glucose concentration, and the bottom light reflection intensity R increased. However, when the concentration of the glucan exceeds a certain value, the dispersion of the red blood cells can be caused, so that the light scattering of the blood becomes strong, and the OCTSS and the R are all in the opposite direction. Potential. In addition, with the increase of the blood cell pressure product (HCT), the specific gravity of red blood cells in the blood increased, the scattering particles increased, and the light scattering of the blood was enhanced, showing that the OCTSS was increased and R was lower. F.2. The optimal separation of the plasma fibrinogen was determined by using OCT to investigate the optical properties of the fibrinogen-free blood at different dextran concentrations. The results showed that the OCTSS of the blood after treatment with the chemical precipitation method (cold ethanol method and the sulfuric acid method) was different with the increase of the concentration of the dextran. The blood after the freeze-thaw method, whose optical parameters change with the concentration of the dextran. Therefore, the method for optimal removal of the plasma fibrinogen is 3. After the plasma is removed by the optimal method, the plasma of different concentration is prepared by using the external human plasma fibrinogen dry powder, and then the blood of different fibrinogen concentration is studied. It was found that the blood OCTSS and R of the blood did not increase with the fibrinogen concentration due to the weak aggregation of the fibrinogen dry powder on the red blood cells of the pig. It is found that OCTSS has a significantly reduced tendency to increase with the increase of Fg in human blood. When the plasma fibrinogen concentration exceeds the normal range of the human body (2-4g/ L), the OCTSS value is reduced to a relatively low level, showing a strong risk of high risk of blood Fg. and the bottom reflection peak r can not effectively reflect the fiber egg in the plasma due to the influence of the instrument and the experimental material used. In addition, other factors such as blood cell pressure, blood flow rate, cell-specific factors, etc. have a certain effect on the change of OCTSS. In general, optical coherence tomography, as a new type of non-destructive testing technique, can be expected to be an ideal method for the detection of blood fibrin by developing a new method of simultaneous detection of other blood properties and a reasonable means of calibration to eliminate the effects of other factors.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.51

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