The Quantitative Calculation Of Simulative Eccentric Mitral Regurgitation Based On Ultrasonic Doppler Flow Imaging

Mitral valve disorder is one of the most common diseases of the heart. Accurately quantitative assessment to mitral regurgitation is important to clinical repair or choose surgical opporunity to displace mitral valve. At present, echocardiography is the most common non-invasive diagnostic tool for the visualization of intracardiac blood flow, and it is easy to operate, and with low cost. For the presence of disturbed flow and it's complication, there is no model for turbulent flow in the heart. No single precise method is routinely used as a "golden standard" for clinical quantitative evaluation of mitral regurgitation, especially the eccentric regurgitation. Most doctors are still relying on experience or a semi-quantitative method to judge the severity of mitral regurgitation,which limit the clinical use of color Doppler echocardiography for evaluation of eccentric mitral regurgitation.In this thesis, we will simulate eccentric mitral regurgitation and image the doppler flow imaging through using ultrasound simulation software Field_II based on the model presented. Through quantitative calculation of simulative regurgitation rate and the standard model's regurgitation rate, we analysis the angle facor to estimated regurgitation rate., than present a quantitative relationship between angle and size of regurgitation. It will have a help to establish a "golden standard" for clinical quantitative evaluation of eccentric mitral regurgitation and the model of quantitative assessment.First, after the systematic study the relationship between the wall jet and the mathematical model of eccentric mitral regurgitation, according to the hemodynamic features of eccentric mitral regurgitation we establishment two mathematical model of eccentric mitral regurgitation, a valve size is d=0.01m, no negative return flow, a valve size is d=0.005m , negative return flow, though integrating laboratory research results and the foreign recent study reported. According to the presented mathematical model, we get the doppler flow imaging of six angles of two model through using ultrasound simulation software Field_II. Than, we analysis the each angle facor to image the doppler flow imaging, carry out velocity extraction of a cross-section through applying auto-correlation technique used most of the commercial color flow imaging system. Third, in the area from the valve 2cm-4cm, we select 21 cross-section separated by 0.1cm to quantificationally calculate the regurgitation rate and show the calculation results of six angles of two model with charts. Finally, we compare the calculation results with the model value, carefully research the impact of severity about the angles and the evaluation of eccentric mitral regurgitation.The results showed that the calculation values of mitral regurgitation is underestimated compare with the true value, and with the angle continues to increase, the amount underestimated correspondingly increase. It is coincident with the actual situation. Furthermore, it is indicated that it is best to keep control of the angle within 20 degrees when doctor manipulate ultrasound doppler to estimate the severity of eccentric mitral regurgitation, because this could effectively reduce the findings seriously underestimated as the reasons of the angle. By comparing change trend of the two models' percentage of the difference and model value, it is finded that the percentage of two models is highly correlative (r=0.9977) despite of the different models. On this foundation, we least square fit a quantitative relationship between the percentage underestimated and angles. It can be used to correct the regurgitation rate underestimated and improve the clinical assessment accuracy of eccentric mitral regurgitation.