基于超声开放系统的角膜粘弹性定量测量与成像研究

发布时间：2018-07-07 16:09

本文选题：超声弹性成像 + 角膜粘弹性　；参考：《深圳大学》2017年硕士论文

【摘要】：角膜组织的生物力学特性与全眼的屈光能力具有非常重要的联系,然而这些特性具有个体差异,且会因病变或外科手术而发生改变。因此,对角膜扩张、圆锥角膜的早期诊断与治疗,评价角膜胶原交联术的治疗效果,以及对屈光矫正术的术前手术方案设计与风险评估,提高对青光眼筛查的效果都离不开对角膜生物力学特性的在体定量评估。本论文研究旨在开发一种利用超声方法在体定量评估角膜生物力学特性的系统,并验证该方法的有效性及在体应用的可行性。具体原理为:基于VerasonicsTM Vantage256超声开放系统,通过控制线阵探头产生声辐射力作用于角膜组织引起组织局部振动,然后使用该探头通过快速平面波成像方式检测兰姆波在角膜组织中的传播,计算兰姆波的群速度与对应的兰姆波速度频散,基于漏兰姆波相速度与力学特性之间的数学关系估计角膜的粘弹性。论文研究中设计了两种胶原交联(Collagen Cross-Linking,CXL)处理方法改变角膜的硬度,并对两种交联方法的效果进行了定量分析与横向评估。评估结果表明加入0.1%戊二醛的处理方法对角膜的硬化效果更明显。其中,加戊二醛的CXL处理组5min、10min、30min、60min对应的弹性值比直接核黄素-UVA处理组的弹性模量分别增大了148.78%、335.68%、392.59%、250.47%。通过剪切弹性与杨氏模量间的数学关系将超声测量的结果转换为杨氏模量,与角膜单向拉伸实验的结果进行对比,两者结果基本吻合。离体实验结果表明该方法可以有效区分不同交联方法在硬度改变效果上的差异。此外,论文研究还设计了对整个离体角膜表面的粘弹性定量成像,使用4%浓度的福尔马林溶液灼烧角膜的局部表面,最后良好的获取了角膜灼烧前与角膜灼烧后的粘弹性成像图,对应的弹性分布图可以非常好的区分出角膜灼烧部位与角膜其他部位的弹性值差异,且灼烧部位的弹性值显著增大,进一步验证了该超声平台的有效性。最后,本论文研究对活体兔眼角膜的生物力学特性测量进行了探索,获得了一些关于活体动物实验的宝贵经验。本论文对所提出的角膜粘弹性定量测量方法的测量准确性、有效性,以及角膜弹性成像和在体测量的可行性进行了验证和评估。该方法可独立成一个系统,也可以集成于现有商业超声仪器作为附加功能模块,未来有望在眼科临床中发挥重要的作用。
[Abstract]:The biomechanical properties of the corneal tissue are very important in relation to the refractive power of the whole eye. However, these characteristics have individual differences and can be altered by disease or surgery. Preoperative design and risk assessment to improve the effect of glaucoma screening can not be separated from the quantitative assessment of the biomechanical properties of the cornea. The purpose of this paper is to develop a system to evaluate the biomechanical properties of the cornea quantitatively by ultrasonic method, and to verify the effectiveness of the method and the feasibility of its application in vivo. The body principle is: Based on the VerasonicsTM Vantage256 ultrasonic open system, the local vibration of the tissue caused by the radiation force of the linear array probe is controlled by the acoustic radiation force. Then the probe is used to detect the propagation of Lamb wave in the corneal tissue by fast plane wave imaging, and the group velocity of Lamb wave and the corresponding Lamb wave velocity are calculated. Degree frequency dispersion, based on the mathematical relationship between the phase velocity of the Lamb wave and the mechanical properties of the cornea, the viscoelasticity of the cornea was estimated. In this paper, two kinds of collagen crosslinking (Collagen Cross-Linking, CXL) treatment methods were designed to change the hardness of the cornea, and the effects of the two crosslinking methods were quantitatively analyzed and laterally evaluated. The evaluation results showed that the result was 0.1. The treatment of% glutaraldehyde has more obvious effect on cornea hardening. The elastic values of 5min, 10min, 30min and 60min in the CXL treatment group of glutaraldehyde increase by 148.78%, 335.68%, 392.59% respectively than those of the direct riboflavin -UVA treatment group, and 250.47%. through the mathematical relationship between the shear elasticity and the young's modulus. The results were compared with the results of the uniaxial tensile test. The results of the two experiments showed that the method could effectively distinguish the difference between the different crosslinking methods in the effect of hardness change. In addition, the paper also designed the viscoelastic quantitative imaging of the whole corneal surface, using 4% concentration. The formalin solution burned the local surface of the cornea. Finally, the viscoelastic imaging of the cornea was obtained before and after the burning of the cornea. The corresponding elastic distribution map could distinguish the difference between the corneal burning site and the rest of the cornea, and the elastic value of the burning position was significantly increased. The effectiveness of the ultrasonic platform. Finally, this paper explores the measurement of the biomechanical properties of the cornea of the living rabbit, and obtains some valuable experiences on living animal experiments. The accuracy and effectiveness of the proposed method of quantitative corneal viscoelasticity measurement, as well as the feasibility of corneal elastography and measurement in vivo The method is verified and evaluated. The method can be an independent system and can be integrated into the existing commercial ultrasonic instruments as an additional functional module. The future is expected to play an important role in the clinical ophthalmology.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R77

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