低场核磁共振信号处理方法研究

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3.0 侯斌 2025-01-09 4 4 3.83MB 71 页 15积分
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低场核磁共振信号处理方法研究
生物医学工程
李新军
聂生东 教授
二○一年十二月
学校代码10252
学号:092461147
上海理工大学硕士学位论文
低场核磁共振信号处理方法研究
李新军
医疗器械与食学院
生物医学工程
研究方向 医学图像处理
指导教师 聂生东 教授
学位论文完成日期 201112
University of Shanghai for Science and Technology
Master Dissertation
Signal Processing of Low-field Nuclear
Magnetic Resonance
Name Li Xinjun
Department College of Medical Instrument and Food
Engineering
Specialty Biomedical Engineering
Research Direction Medical Image Processing
Supervisor Professor Nie Shengdong
Complete Data December 2011
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摘要
随着核磁共振技术的发展,低场核磁共振已经能够用于检测样品中组分的
类及含量等,具有测量方便、快速、无损、无副作用等优点,并且制造、维护、
应用成本低,在生物能源、纺织、环保、粮油食品、农业与生物、油勘探、石
油化工、聚合物材料等方面有很广的应用前景。为了满足这些领域需求,必
须对采集到的核磁共振信号进行反演处理以提取信号中的有用信息。
一维反演技术在石油测井领域开展研究的时间最早,成果最多,而在其他领
域的研究仍未完展开经过一维反演可得到用于分析样品的组成及性质的核磁
共振一维谱,当其中多种组分的谱线相互叠加时,会使检测结果出很大误差,
二维反演技术可很好的弥补这一缺陷。
近几年国外具备二维反演功能的低场核磁共仪器已经商业化,而国内这方
面的研究相对落后,仍然一维反演为主,二维反演尚处于起步阶,而且由于
技术封锁、商业机密等原因,国内公开的相关研究资料很少。本文在分析了石
油测井领域一维反演技术的基础上,结合国内公开的有限的二维反演资料,提
出了一种新的扩散系数横向弛豫时间(DT2)二维反演算法
本文首先对目前公开的一维反演算法进行详尽的分析,然后结合用于一维反
演的改进的奇异值分解算法和联合代修正算法的思想对二维反演方程中的核
心函数矩阵进行分解,最后经过大量实验和理研究确定反演过程中各个参数的
设置,并根据分解的矩阵进行 DT2二维反演。
大量实验证明,本文算法能够得到理想的结果,并且所做的改进能够大幅度
降低计算量,减少消耗的计算机内存,提高 DT2二维反演的速度。
词: 共振 系数 弛豫时间 反演
ABSTRACT
With the development of Nuclear Magnetic Resonance (NMR), Low-field NMR
has been able to detect the types and contents of sample compositions, and it is
convenient, fast and non-destructive without side effects. As the NMR equipments cost
little money to manufacturing, maintance and using, it has a very broad application
prospect in bio-energy, textile, environmental protection, foodstuff, agriculture, oil
exploration, petrochemicals, and polymer materials and so on. To meet all needs of
these areas, the signal collected with NMR equipment must be processed with inversion
to extract useful information.
The earliest research of one-dimension inversion is in Nuclear Magnetic
Resonance oil logging with most research results while the research in other areas has
not yet been expanded. One-dimension NMR spectra got from one-dimension inversion
can be used to analyze the composition and characteristic of samples. The conclusion
got from the one-dimension spectra should be wrong if there are some spectral lines of
ingredients in samples are superimposed, and the two-dimension spectra can solve the
problem effectively.
Some low-field NMR equipment with two-dimension inversion function
manufactured by foreign companies have been sold in market, but the domestic
technology of two-dimension inversion is backward, most researches in this area are
mainly the one-dimension inversion, and two-dimension inversion is still in its infancy.
With the reasons of technology blockade, trade secrets protection and so on, there are
only a little domestic and foreign public technical information can be got on the internet.
In this paper, we introduce a new diffusion-T2 relaxation two-dimension inversion
algorithm, based on the analysis of one-dimension inversion in Nuclear Magnetic
Resonance oil logging and the limited domestic and foreign public technical
information.
We make an elaborate analysis of the public one-dimension inversion algorithm
first. Then combined of the idea of improved Singular Value Decomposition algorithm
and the joint iterative correction algorithm, we divide the core function matrix into two
small matrixes. At last, doing a large number of experiments and theory researches we
get some parameters value. Last we introduce a new diffusion-T2 relaxation
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