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  本文關(guān)鍵詞： 二尖瓣偏心反流 Field_II超聲模擬 附壁射流模型 定量計算　出處：《四川大學》2007年碩士論文　論文類型：學位論文

【摘要】： 二尖瓣病變是心血管病中最常見的疾病之一，二尖瓣反流的精確定量評價對于臨床修復(fù)或置換瓣膜手術(shù)的時機選擇以及術(shù)后評估都有著重要的指導(dǎo)意義。目前，基于超聲多普勒成像的二尖瓣檢查成為反流評價最重要的工具，它操作簡便、無副作用、成本低。然而，由于流場的復(fù)雜性，目前缺乏相關(guān)的流場模型，迄今為止，對于臨床二尖瓣偏心反流的評價沒有金標準，大部分醫(yī)生仍是根據(jù)彩色多普勒憑借經(jīng)驗或用半定量的方法判斷反流的嚴重程度，這在某種程度上限制了臨床上利用彩色多普勒超聲心動圖對二尖瓣偏心反流進行評估的應(yīng)用。 本文在給出血流模型的基礎(chǔ)之上，運用超聲模擬軟件Field_Ⅱ，模擬二尖瓣偏心反流并成像。并通過定量計算的反流率與模型的標準反流率進行比較，分析角度大小對反流量估計的影響因素，提出角度與反流量大小的一個定量關(guān)系，為建立臨床二尖瓣偏心反流定量評價模型和制定評價金標準提供一定的依據(jù)。 首先在系統(tǒng)研究了附壁射流數(shù)學模型與二尖瓣偏心反流模型之間的關(guān)系后，根據(jù)二尖瓣反流的血流動力學以及反流的特征并綜合實驗室以前的研究成果及目前國外最近的研究報道，建立了兩種偏心反流的數(shù)學模型，第一種為瓣口尺寸d=0.01m，沒有負向回流；第二種為瓣口尺寸d=0.005m，有負向回流。用超聲模擬軟件field_Ⅱ，根據(jù)給出的數(shù)學模型實現(xiàn)了兩種情況下二尖瓣偏心反流的模擬顯像，獲得了兩種模型下6個角度的模擬成像結(jié)果，分析了各個角度對于血流成像的影響，并利用所獲得的rf信號，，通過目前大多數(shù)商品化彩色血流圖系統(tǒng)采用的自相關(guān)技術(shù)實現(xiàn)了截面的速度信息提取。然后選取距離瓣口2cm-4cm的范圍內(nèi)相隔0.1cm的21個截面進行定量計算，以圖表的形式給出了兩個模型下6種常用角度的估計值結(jié)果，并與模型值進行比較，詳細分析了成像角度對于偏心反流嚴重程度的評價影響。 結(jié)果表明超聲估計出來的反流量確實是要比真實值要低估，而且隨著角度的不斷增加，低估的量也相應(yīng)的增大，這個和實際的情況是一致的。而且隨著角度的不斷增大，各個角度的反流率低估的趨勢不斷增加，并指出在用超聲多普勒對二尖瓣偏心反流嚴重程度進行估計時，最好把成像的角度控制在20度之內(nèi)，這樣可以有效的減小由于角度原因?qū)υ\斷結(jié)果的嚴重低估。通過對比兩種模型下，計算值與模型值的差值與模型值本身的百分比的變化趨勢及相關(guān)性分析，指出盡管模型不同，但是兩組百分比卻成高度相關(guān)(r=0.9977)。以此為據(jù)，利用最小二乘擬合出了超聲成像角度與低估百分比之間的一個定量關(guān)系，可以用于修正估計出來的反流量，提高臨床上評估二尖瓣偏心性反流程度的精確性。
[Abstract]:Mitral valve disease is one of the most common diseases in cardiovascular disease. The accurate quantitative evaluation of mitral regurgitation is of great significance for the choice of time for clinical repair or replacement valve surgery and for postoperative evaluation. Mitral valve examination based on Doppler ultrasound is the most important tool for reflux evaluation. It is easy to operate, has no side effects, and has low cost. However, due to the complexity of flow field, there is a lack of relevant flow field models. There is no gold standard for the evaluation of clinical eccentric mitral regurgitation, and most doctors still judge the severity of regurgitation on the basis of color Doppler experience or semi-quantitative methods. This limits the clinical application of color Doppler echocardiography in the assessment of eccentric mitral regurgitation. Based on the model of bleeding flow, this paper uses the ultrasonic simulation software FieldII to simulate the eccentric mitral regurgitation and imaging, and compares the reflux rate calculated quantitatively with the standard regurgitation rate of the model. This paper analyzes the influence factors of angle size on back flow estimation, and puts forward a quantitative relationship between angle and reverse flow, which provides a certain basis for establishing a quantitative evaluation model of eccentric mitral regurgitation and establishing the evaluation gold standard for clinical mitral eccentricity regurgitation. Firstly, the relationship between the mathematical model of the wall attached jet and the eccentric regurgitation model of the mitral valve is studied systematically. According to the hemodynamics of mitral regurgitation and the characteristics of mitral regurgitation, two kinds of mathematical models of eccentric regurgitation were established according to the previous research results in laboratory and recent reports abroad. The second is the valve orifice size dn0. 005m, with negative reflux. By using the ultrasonic simulation software fieldII, the simulation imaging of mitral eccentric regurgitation in two cases is realized according to the given mathematical model, and the simulated imaging results of 6 angles under two models are obtained. The effects of different angles on blood flow imaging are analyzed, and the obtained RF signals are used. The velocity information of the cross section is extracted by autocorrelation technique which is used in most commercial color flow chart systems at present. Then 21 sections with a distance of 0.1 cm within the distance of 2cm-4cm from the valve orifice are selected for quantitative calculation. The estimation results of six common angles under two models are given in the form of charts, and compared with the values of the model, and the influence of imaging angle on the severity of eccentric reflux is analyzed in detail. The results show that the inverse flow estimated by the ultrasound is indeed lower than the true value, and with the increasing of the angle, the undervalued amount increases accordingly, which is consistent with the actual situation. And with the increasing of the angle, The tendency to underestimate the reflux rate at all angles is increasing, and it is pointed out that in estimating the severity of eccentric mitral regurgitation with Doppler ultrasound, it is best to keep the imaging angle within 20 degrees. By comparing the difference between the calculated value and the model value and the percentage of the value of the model itself, it is pointed out that although the model is different, the difference between the calculated value and the value of the model is different. However, the two groups of percentages were highly correlated to 0.99770.The least square method was used to fit a quantitative relationship between the angle of ultrasound imaging and the under-estimated percentage, which could be used to correct the estimated backflow. Improve clinical accuracy in assessing the degree of eccentric mitral regurgitation.
【學位授予單位】：四川大學
【學位級別】：碩士
【學位授予年份】：2007
【分類號】：R312

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相關(guān)碩士學位論文 前2條

1 張建;二尖瓣偏心反流定量計算的超聲模擬研究[D];四川大學;2007年

2 鄧敏;二尖瓣反流的超聲成像模擬[D];四川大學;2006年

本文編號：1525772