本文選題：橢圓中心軌跡 + 三維時(shí)間飛躍法��； 參考：《杭州電子科技大學(xué)》2017年碩士論文

【摘要】：近年來(lái),隨著磁共振成像技術(shù)在科學(xué)研究和臨床應(yīng)用上的不斷發(fā)展,新技術(shù),新方法層出不窮,用于解決傳統(tǒng)掃描方式的長(zhǎng)掃描時(shí)間,低圖像信噪比等問(wèn)題。而本文的工作就是對(duì)傳統(tǒng)的三維時(shí)間飛躍法血管成像序列的一個(gè)改進(jìn)。在傳統(tǒng)的時(shí)間飛躍法血管成像序列中,高信噪比,高對(duì)比度,高分辨率的血管圖像需要耗費(fèi)較長(zhǎng)的掃描時(shí)間,并且施加在相位以及讀出方向的流動(dòng)補(bǔ)償梯度會(huì)導(dǎo)致回波時(shí)間(echo time,TE)的增加。針對(duì)上述問(wèn)題,本文提出了基于k空間橢圓中心軌跡的三維時(shí)間飛躍法血管成像雙回波序列的設(shè)計(jì)方法,與傳統(tǒng)的三維時(shí)間飛躍血管成像單回波序列相比,其有效回波時(shí)間縮短了0.7ms,并且掃描時(shí)間減少了61%。為評(píng)價(jià)本序列的合理性和有效性,本文對(duì)該序列進(jìn)行了詳細(xì)的解釋,并與相關(guān)的序列進(jìn)行了比較。同時(shí),通過(guò)采用各個(gè)序列對(duì)人體大腦進(jìn)行數(shù)據(jù)采集,然后定量地測(cè)量血管的對(duì)比度噪聲比(contrast to noise ratio,CNR)來(lái)驗(yàn)證該序列的可行性。主要的工作包括:(1)傳統(tǒng)的三維時(shí)間飛躍法血管成像雙回波序列的設(shè)計(jì)傳統(tǒng)的三維時(shí)間飛躍法血管成像雙回波序列的設(shè)計(jì)是在傳統(tǒng)的三維時(shí)間飛躍法血管成像單回波序列的基礎(chǔ)上進(jìn)行的改進(jìn),其中傳統(tǒng)單回波序列主要采用了短的不對(duì)稱射頻激發(fā)脈沖,最小持續(xù)時(shí)間梯度,以及部分回波采集。針對(duì)單回波序列循環(huán)過(guò)程中的冗余時(shí)間,在一個(gè)循環(huán)過(guò)程引入額外的相位編碼梯度和讀出回波梯度,有效地將k空間填充時(shí)間減少一半,從而實(shí)現(xiàn)傳統(tǒng)三維時(shí)間飛躍法血管成像雙回波序列設(shè)計(jì)。序列的設(shè)計(jì)是通過(guò)在聯(lián)影醫(yī)療科技有限公司的開(kāi)發(fā)平臺(tái)ADEPT上進(jìn)行C++語(yǔ)言的編寫來(lái)實(shí)現(xiàn)。(2)基于k空間橢圓中心軌跡的三維時(shí)間飛躍法血管成像雙回波序列的設(shè)計(jì)基于k空間橢圓中心軌跡的三維時(shí)間飛躍法血管成像雙回波序列的設(shè)計(jì)同樣是在傳統(tǒng)的三維時(shí)間飛躍法血管成像單回波序列的基礎(chǔ)上,通過(guò)重新設(shè)計(jì)k空間的遍歷方式進(jìn)行添加修改。其中k空間的遍歷軌跡的設(shè)計(jì)是通過(guò)MATLAB軟件實(shí)現(xiàn),然后通過(guò)C++語(yǔ)言寫入序列開(kāi)發(fā)平臺(tái)。(3)人體大腦韋利斯環(huán)區(qū)域的數(shù)據(jù)采集及成像序列的可行性需要通過(guò)實(shí)際的臨床效果來(lái)進(jìn)行驗(yàn)證。通過(guò)選擇合適的參數(shù),對(duì)五位健康人體被試的大腦韋利斯環(huán)區(qū)域進(jìn)行數(shù)據(jù)采集,并且對(duì)于不同的序列方法采集到的圖像進(jìn)行定性和定量上的分析。衡量圖像的優(yōu)劣性主要通過(guò)兩種方式,1)直觀地觀察圖像,是否有血管缺失以及其他偽影;2)定量地測(cè)量某些重要血管的CNR值。上述實(shí)驗(yàn)都是基于聯(lián)影醫(yī)療科技有限公司的1.5T核磁共振掃描儀器上,對(duì)健康人體大腦的韋利斯環(huán)區(qū)域進(jìn)行成像。最終的結(jié)果表明,(1)相比與傳統(tǒng)的三維時(shí)間飛躍法血管成像單回波序列,雖然本序列的血管圖像的CNR值降低了2.5%,但掃描時(shí)間減少了約61%,且回波時(shí)間進(jìn)一步地縮短了0.7ms。而當(dāng)將本序列進(jìn)行重復(fù)采集平均后(兩次采集的總掃描時(shí)間比傳統(tǒng)的單回波掃描時(shí)間少了22%)的結(jié)果與傳統(tǒng)單回波序列相比,本序列的CNR值提高了54.3%;(2)相比與傳統(tǒng)的三維時(shí)間飛躍法血管成像雙回波序列,本序列的優(yōu)點(diǎn)體現(xiàn)在:1)掃描時(shí)間減少了22%,2)CNR值提高了10.9%,3)由于雙回波調(diào)制引入的偽影減少。
[Abstract]:In recent years, with the continuous development of the technology of magnetic resonance imaging, in the scientific research and clinical application of the new technology, new method is used to solve the long scan time emerge in an endless stream, the traditional scanning method, low image SNR. And 3D time-of-flight angiography sequences of the traditional is the work of an improvement. At the time of flight angiography sequence in the traditional, high signal-to-noise ratio, high contrast, high resolution scanning time vascular image takes longer, and applied in the readout direction gradient flow compensation phase and cause the echo time (echo time, TE) increased. In view of the above problems, this paper puts forward the design method of 3D TOF angiography of ellipse center K space trajectory based on double echo sequence, compared with the 3D TOF angiography traditional single echo sequence, the effective echo time reduction Short 0.7ms, and the scan time is reduced by 61%. for the evaluation of the sequence of rationality and validity, this paper gives a detailed explanation of the sequence, and compared with the related sequence. At the same time, through the data acquisition of the human brain using various sequences, then quantitative measurements of blood vessels in contrast to noise ratio (contrast to noise ratio, CNR) to verify the feasibility of the series. The main work includes: (1) design of 3D TOF angiography design of traditional TOF angiography in traditional double echo sequence double echo sequence is improved based on 3D TOF angiography in traditional single echo sequence on the traditional single echo sequence mainly adopts asymmetric RF short excitation pulse duration, minimum gradient, and echo acquisition. For the single echo sequence cycle The redundancy time, introducing additional phase encoding gradient in a cyclic process and readout echo gradient, K space filling time can be effectively reduced by half, to achieve the traditional 3D time-of-flight angiography double echo sequence. The sequence design design is written in C++ language to achieve the ADEPT development platform in the movie Medical Technology Co. the company. (2) based on the design of 3D TOF angiography of ellipse center trajectory K space double echo sequence design based on 3D time-of-flight angiography of ellipse center trajectory K space double echo sequence is also based on 3D time-of-flight angiography in traditional single echo sequence, add modify the way by traversing the re design of the K space. The design of the K space trajectory traversal is realized by MATLAB software, and then through the C++ language write sequence Development platform. (3) the feasibility of human brain Willis ring region sequence data acquisition and imaging through the actual clinical effect need to verify. By choosing appropriate parameters, collect the data of five healthy human subjects brain Willis Circle area, and the qualitative and quantitative analysis on different sequences methods collected images. The image quality measure mainly through two ways: 1) to visually observe image, whether there is lack of blood vessels and other artifacts; 2) to quantitatively measure some important vascular CNR value. The experiment is based on the 1.5T magnetic resonance scanner movie Medical Technology Company Limited. The imaging area of the circle of Willis, healthy human brain. The final results show that (1) compared with the TOF angiography traditional single echo sequence, although the vascular image sequence The CNR value decreased by 2.5%, but the scan time is reduced by about 61%, and the echo time further shortened when the 0.7ms. sequence was repeated after the average acquisition (two acquisition of the total scanning time were 22% less than the traditional single echo scanning time) the results of traditional single echo sequence in the sequence the CNR value increased by 54.3%; (2) compared with the TOF angiography of traditional double echo sequence, the sequence of advantages embodied in: 1) the scan time is reduced by 22%, 2) CNR value increased by 10.9%, 3) due to artifacts of dual echo modulation is introduced to reduce.

【學(xué)位授予單位】：杭州電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：R445.2;TP391.41

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 方文星;低場(chǎng)磁共振3D TOF腦血管成像序列優(yōu)化研究[D];浙江大學(xué);2014年

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本文編號(hào)：1765315