高频超声灰阶血流成像关键技术的研究与实现

发布时间：2018-05-21 13:34

本文选题：高频超声 + 血流成像　；参考：《北京协和医学院》2015年硕士论文

【摘要】：医学超声成像技术以其无创、安全、实时成像等优点应用广泛。超声血流成像是超声诊断的重要分支,可以准确直观地反映组织内部的供血状况,为临床诊断提供多方位信息；其中灰阶血流成像技术以其高分辨力、无角度依赖等特点具有重要的研究价值。本文提出了一种新的灰阶血流成像方法,旨在实现高频条件下血流图像的获取,克服传统技术的操作复杂、参数依赖、高频不适用等缺点,并建立理论支撑体系作为高频血流成像领域的重要补充。首先根据血液中的主要散射体即红细胞的特征,分析其背向散射特性,综合超声衰减因素并建立散射模型,从而确定在高频条件下浅表部位血流成像的可行性和成像的频率范围；然后由理论推导设计了算法和实现方式,根据组织和血流信息的差异性来获取血流信息,从而将较弱的血液回声和较强的组织回声区分开来,实现灰阶血流成像。论文基于可编程逻辑器件完成了实验平台的设计,用不同频率的探头验证理论模型的正确性；并使用20MHz超声扫描探头、使用模拟血液、模拟血管得到血流图像,成像结果与实际相符,且该方法对于0.3mm的血管内血流分辨清晰；本文进一步研究图像的亮度值与血液流速的关系：流速7.4cm/s至44.5cm/s线性度较好,在51.9cm/s时亮度达到最大值,并论证不同的扫描方式对成像结果的影响；最后运用该方法对人手背部静脉成像,可以得到血管内清晰的超声血流图。该方法在高频超声成像时无需采用传统的脉冲编码方式,仅单脉冲扫描即可获取微弱的血流信息,同时具有与结构成像相同的高分辨力,为浅表器官的疾病诊断提供了可靠依据,具有较好的实际应用价值。
[Abstract]:Medical ultrasound imaging technology is widely used because of its advantages of non-invasive, safety and real-time imaging. Ultrasound blood flow imaging is an important branch of ultrasonic diagnosis, which can accurately and intuitively reflect the blood supply status in tissues and provide multi-directional information for clinical diagnosis. The characteristics of angle-free dependence have important research value. In this paper, a new gray-scale blood flow imaging method is proposed, which aims to obtain blood flow images at high frequency, and overcome the disadvantages of complex operation, parameter dependence and inapplicability of high frequency. The theoretical support system is established as an important supplement in the field of high frequency blood flow imaging. Firstly, according to the characteristics of the main scatterer in blood, red blood cell (RBC), the backscattering characteristics are analyzed, and the ultrasonic attenuation factors are synthesised and the scattering model is established. In order to determine the feasibility of superficial blood flow imaging and the frequency range of imaging under the high frequency condition, then the algorithm and implementation method are designed by theoretical derivation, and the blood flow information is obtained according to the difference of tissue and blood flow information. In order to distinguish the weak blood echo from the strong tissue echo, the gray-scale blood flow imaging can be realized. The experiment platform is designed based on programmable logic device, and the theoretical model is verified by different frequency probe, and the blood flow image is obtained by using 20MHz ultrasonic scanning probe and simulated blood vessel. The imaging results are consistent with the actual results, and the resolution of intravascular blood flow in 0.3mm is clear. In this paper, the relationship between image brightness and blood flow velocity is further studied: the linearity between 7.4cm/s velocity and 44.5cm/s velocity is good, and the brightness reaches the maximum value at 51.9cm/s. The effects of different scanning methods on the imaging results were demonstrated. This method can obtain weak blood flow information only by single pulse scanning without using the traditional pulse coding method in high frequency ultrasonic imaging, and it has the same high resolution as structural imaging. It provides a reliable basis for the diagnosis of superficial organ diseases and has good practical application value.
【学位授予单位】：北京协和医学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R445.1

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