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

【摘要】：近年來,隨著磁共振成像技術在科學研究和臨床應用上的不斷發(fā)展,新技術,新方法層出不窮,用于解決傳統(tǒng)掃描方式的長掃描時間,低圖像信噪比等問題。而本文的工作就是對傳統(tǒng)的三維時間飛躍法血管成像序列的一個改進。在傳統(tǒng)的時間飛躍法血管成像序列中,高信噪比,高對比度,高分辨率的血管圖像需要耗費較長的掃描時間,并且施加在相位以及讀出方向的流動補償梯度會導致回波時間(echo time,TE)的增加。針對上述問題,本文提出了基于k空間橢圓中心軌跡的三維時間飛躍法血管成像雙回波序列的設計方法,與傳統(tǒng)的三維時間飛躍血管成像單回波序列相比,其有效回波時間縮短了0.7ms,并且掃描時間減少了61%。為評價本序列的合理性和有效性,本文對該序列進行了詳細的解釋,并與相關的序列進行了比較。同時,通過采用各個序列對人體大腦進行數(shù)據(jù)采集,然后定量地測量血管的對比度噪聲比(contrast to noise ratio,CNR)來驗證該序列的可行性。主要的工作包括:(1)傳統(tǒng)的三維時間飛躍法血管成像雙回波序列的設計傳統(tǒng)的三維時間飛躍法血管成像雙回波序列的設計是在傳統(tǒng)的三維時間飛躍法血管成像單回波序列的基礎上進行的改進,其中傳統(tǒng)單回波序列主要采用了短的不對稱射頻激發(fā)脈沖,最小持續(xù)時間梯度,以及部分回波采集。針對單回波序列循環(huán)過程中的冗余時間,在一個循環(huán)過程引入額外的相位編碼梯度和讀出回波梯度,有效地將k空間填充時間減少一半,從而實現(xiàn)傳統(tǒng)三維時間飛躍法血管成像雙回波序列設計。序列的設計是通過在聯(lián)影醫(yī)療科技有限公司的開發(fā)平臺ADEPT上進行C++語言的編寫來實現(xiàn)。(2)基于k空間橢圓中心軌跡的三維時間飛躍法血管成像雙回波序列的設計基于k空間橢圓中心軌跡的三維時間飛躍法血管成像雙回波序列的設計同樣是在傳統(tǒng)的三維時間飛躍法血管成像單回波序列的基礎上,通過重新設計k空間的遍歷方式進行添加修改。其中k空間的遍歷軌跡的設計是通過MATLAB軟件實現(xiàn),然后通過C++語言寫入序列開發(fā)平臺。(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實際的臨床效果來進行驗證。通過選擇合適的參數(shù),對五位健康人體被試的大腦韋利斯環(huán)區(qū)域進行數(shù)據(jù)采集,并且對于不同的序列方法采集到的圖像進行定性和定量上的分析。衡量圖像的優(yōu)劣性主要通過兩種方式,1)直觀地觀察圖像,是否有血管缺失以及其他偽影;2)定量地測量某些重要血管的CNR值。上述實驗都是基于聯(lián)影醫(yī)療科技有限公司的1.5T核磁共振掃描儀器上,對健康人體大腦的韋利斯環(huán)區(qū)域進行成像。最終的結果表明,(1)相比與傳統(tǒng)的三維時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%,但掃描時間減少了約61%,且回波時間進一步地縮短了0.7ms。而當將本序列進行重復采集平均后(兩次采集的總掃描時間比傳統(tǒng)的單回波掃描時間少了22%)的結果與傳統(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)的三維時間飛躍法血管成像雙回波序列,本序列的優(yōu)點體現(xiàn)在:1)掃描時間減少了22%,2)CNR值提高了10.9%,3)由于雙回波調制引入的偽影減少。
[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.

【學位授予單位】：杭州電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：R445.2;TP391.41

【參考文獻】

相關碩士學位論文 前1條

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

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本文編號：1765315