本文選題：擴(kuò)散張量成像(DTI)　切入點(diǎn)：Q-Ball成像(QBI)　出處：《天津大學(xué)》2012年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：本論文結(jié)合國(guó)家自然科學(xué)基金項(xiàng)目,對(duì)交叉、彎曲、分叉等復(fù)雜腦白質(zhì)纖維重建方法進(jìn)行研究。論述了常見(jiàn)的擴(kuò)散張量成像(DTI)、Q-Ball成像(QBI)和四階張量成像(DT4)的原理、計(jì)算過(guò)程及主要的優(yōu)缺點(diǎn)。主要研究?jī)?nèi)容如下: 首先,針對(duì)多梯度DTI,運(yùn)用多元線(xiàn)性回歸的方法求解其擴(kuò)散張量矩陣;并利用梯度編碼矩陣的條件數(shù)和各向異性標(biāo)準(zhǔn)偏差作為定量評(píng)價(jià)采樣方案和成像精度的標(biāo)準(zhǔn);然后用20梯度方向方案與傳統(tǒng)的6方向和12方向的方案進(jìn)行對(duì)比,以評(píng)價(jià)梯度方向數(shù)對(duì)成像質(zhì)量的影響。 其次,針對(duì)QBI來(lái)重建方向分布函數(shù)的方法,研究了其重建的Funk-Radon變換基本理論、高斯徑向基函數(shù)插值的方法和在MATLAB中進(jìn)行曲面重建的方法;并討論了實(shí)驗(yàn)參數(shù)如視場(chǎng)大小(FOV)、b值等對(duì)圖像信噪比、空間分辨率和掃描時(shí)間的影響;最后對(duì)結(jié)構(gòu)較復(fù)雜處如視輻射線(xiàn)、前額皮質(zhì)等用QBI成像以觀(guān)察成像效果。 再次,針對(duì)QBI的缺陷,研究了DT4重建的基本原理和計(jì)算過(guò)程以及參數(shù)如角度重建誤差、規(guī)范化各向異性等的表達(dá)形式;又引進(jìn)計(jì)算機(jī)仿真的方法定量地評(píng)價(jià)不同噪聲值和采樣梯度方向數(shù)對(duì)重建角度誤差和規(guī)范化張量標(biāo)準(zhǔn)偏差等的影響;然后從算法、實(shí)驗(yàn)和成像效果三方面對(duì)DTI、QBI、和DT4成像進(jìn)行對(duì)比,以證明DT4在未來(lái)臨床應(yīng)用中更有優(yōu)勢(shì)和潛力。 本文完成了DTI、QBI和DT4成像的可視化研究,將可視化的結(jié)果與人類(lèi)大腦的解剖結(jié)構(gòu)進(jìn)行比較,驗(yàn)證了研究結(jié)果的正確性,為以后的腦神經(jīng)纖維追蹤和臨床應(yīng)用奠定了理論基礎(chǔ)。
[Abstract]:In this paper, the reconstruction methods of complex white matter fibers, such as crossover, bending and bifurcation, are studied in conjunction with the project of National Natural Science Foundation of China. The principles of diffusion imaging Zhang Liang's Q-Ball imaging QBI4 and fourth order Zhang Liang imaging DT4 are discussed. The main research contents are as follows:. Firstly, the multivariate linear regression method is used to solve the diffusion Zhang Liang matrix for multi-gradient DTI, and the condition number of gradient coding matrix and anisotropic standard deviation are used as the criteria for quantitative evaluation of sampling scheme and imaging accuracy. Then, the 20 gradient direction scheme is compared with the traditional six and twelve directions scheme to evaluate the influence of gradient direction number on the imaging quality. Secondly, the basic theory of Funk-Radon transform, the interpolation method of Gao Si radial basis function and the method of surface reconstruction in MATLAB are studied according to the method of QBI to reconstruct the directional distribution function. The effects of experimental parameters such as field of view (FOV) value on image signal-to-noise ratio (SNR), spatial resolution and scanning time are discussed. Finally, QBI imaging is used to observe the imaging effect for complex structures such as apparent radiation lines and prefrontal cortex. Thirdly, aiming at the defects of QBI, the basic principle and calculation process of DT4 reconstruction and the expressions of parameters such as angle reconstruction error and normalized anisotropy are studied. Computer simulation is introduced to quantitatively evaluate the effects of different noise values and sampling gradient directions on the reconstruction angle error and standardized Zhang Liang standard deviation. In order to prove that DT4 has more advantages and potential in clinical application in the future, the QBI and DT4 imaging are compared in three aspects of experimental and imaging effects. The visualization of DTI QBI and DT4 imaging has been completed in this paper. The results of visualization are compared with the anatomical structure of human brain, and the correctness of the results is verified, which lays a theoretical foundation for the follow-up and clinical application of brain nerve fibers.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類(lèi)號(hào)】：TP391.41;R311

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本文編號(hào)：1577496