基于扩散预备快速自旋回波磁共振指纹技术的同时T2和ADC定量测量

发布时间：2018-11-19 11:34

【摘要】：相比于特定加权的磁共振成像,磁共振定量成像对人体病理组织有着其特有的高灵敏度和组织特异性,并能定量地对疾病的发展变化情况进行评估,因此具有非常重要的临床意义。通常定量成像参数包括纵向弛豫时间(T1),横向弛豫时间(T2)和表观扩散系数(ADC)等。常规方法定量T1和T2耗时很长,虽然利用EPI技术能够快速定量ADC,但是由于其内在的图像畸变又引入了多参数图像的配准问题。目前,磁共振指纹识别技术(MRF)解决了 10秒内同时快速定量T1和T2的问题,成为了定量成像领域中的一个研究热点。然而,现有MRF技术只局限于对T1和T2的测量,并没有将ADC的定量考虑在内,而且基于稳态自由进动(FISP)下的MRF技术对T2的识别度并不是很好。本文针对上述两个MRF技术中的不足,首次提出了基于扩散预备(DP)和快速自旋回波(TSE)模块的MRF技术,简称DP-TSEMRF,实现了同时快速定量T2和ADC参数值。本文从序列设计开始介绍该新技术,阐述了选择DP和TSE模块的原因,并将整个序列分成不同的块(block),每个块的序列参数随着扫描次数而变化。图像重建过程引入了滑动窗(sliding window)和信号重排(rearrangement)的方法。字典建立方面也与现有的MRF有所变化。为了验证DP-TSEMRF技术的有效性,本文分别做了水膜和人体实验,并与金标准结果作对比。其中水膜实验主要考察了在不同T2和ADC情况下,新序列相比标准方法在识别精度上差异。人体实验主要考察了在人体白质纤维各向异性的情况下,新序列相比标准方法在三个基本正交方向上的ADC识别能力,并与FISP-MRF就T2值进行分析比较。结果表明,DP-TSEMRF技术在T2的定量上明显优于FISP-MRF,而且在ADC的定量上具有良好的识别能力。
[Abstract]:Compared with specific weighted magnetic resonance imaging, quantitative magnetic resonance imaging has its unique sensitivity and tissue specificity for human pathological tissues, and can quantitatively assess the development and changes of the disease. Therefore, it has very important clinical significance. The quantitative imaging parameters usually include longitudinal relaxation time (T1), transverse relaxation time (T2) and apparent diffusion coefficient (ADC). Quantification of T _ 1 and T _ 2 by conventional methods takes a long time. Although EPI can be used to quantify ADC, quickly, the problem of multi-parameter image registration is introduced because of its inherent image distortion. At present, (MRF) (Magnetic Resonance fingerprint Identification) has solved the problem of rapid quantification of T1 and T2 within 10 seconds, and has become a research hotspot in the field of quantitative imaging. However, the existing MRF technology is limited to the measurement of T1 and T2, and does not take the quantitative ADC into account, and the recognition degree of T2 based on the MRF technique based on steady-state free-precession (FISP) is not very good. In order to overcome the shortcomings of the above two MRF techniques, a new MRF technique based on diffusion prepared (DP) and fast spin echo (TSE) module is proposed for the first time in this paper. In short, DP-TSEMRF, realizes the simultaneous fast quantification of T2 and ADC parameters. This paper introduces the new technique from sequence design, explains the reasons for choosing DP and TSE modules, and divides the whole sequence into different blocks. The sequence parameters of each block vary with the number of scans. In the process of image reconstruction, sliding window (sliding window) and signal rearrangement (rearrangement) are introduced. Dictionary creation also changes from the existing MRF. In order to verify the effectiveness of DP-TSEMRF technique, water film and human body experiments were carried out respectively, and the results were compared with the results of gold standard. The water film experiment mainly investigated the difference of recognition accuracy between the standard method and the new sequence under different T2 and ADC conditions. In human body experiments, the ADC recognition ability of the new sequence comparison standard method in three basic orthogonal directions under the condition of the anisotropy of human white matter fibers was investigated and compared with the T 2 value of FISP-MRF. The results show that DP-TSEMRF is superior to FISP-MRF, in quantification of T2 and has good recognition ability in ADC.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R445.2

【相似文献】