- 學位論文
利用四維心臟超音波影像評估主動脈順應性
Estimation of Aortic Compliance Using Real-time 4D Echocardiography
摘要
血管順應性(Compliance)是指血管壁內壓力變化時所造成之體積變化量，可當作評估血管硬化程度指標，觀察靠近心臟且具有較大彈性的主動脈量測其順應性便可代表全身動脈順應性總和並了解全身血管硬化程度。 本研究目的是利用心臟超音波影像(Echocardiography)建立一個動態三維心臟模型，再經影像前處理降低超音波斑點雜訊並利用動態邊緣模組(Active Contour Model)圈選主動脈邊緣資訊，評估主動脈於心臟收縮舒張時所產生之應變，計算主動脈形變量推估主動脈順應性達到早期偵測動脈硬化的目的。 使用10位Subjects超音波影像驗證左心室心搏量與主動脈流量關係，結果顯示左心室在心動週期下之左心室心搏量與主動脈流量呈現良好的相關性(R2=0.8837)且差異度都落在正負2倍標準差之內；分析左心室容積與主動脈截面積關係後發現，結果顯示兩參數彼此間相關係數介於0.6到0.85，兩者間呈現負相關，代表左心室收縮將血液射出腔室容積降低時，主動脈截面積同時有擴張情形發生與左心室容積呈負相關性，由此可知本研究提出的方法有一定的準確性；主動脈直徑評估部分10位Subjects最大值平均為29.610±2.551(mm)，最小值平均為24.609±2.715(mm)及差值平均為5.001±1.148(mm)；最後，本研究採用另外3位Subjects已知影像採集當下血壓數值的超音波影像做主動脈順應性評估，結果分別為0.021、0.044及0.038(cm2/mmHg)。 本研究影像圈選與容積估算方法有一定的準確性，利用心臟超音波影像能取得心室容積及主動脈血管順應性等生理資訊評估心臟功能。
並列摘要
Vascular compliance is defined as the volume change induced by the blood pressure change, and it is also an indicator for assessing the vascular stiffness. For accessing the systemic arterial compliance and systemic vascular stiffness, the compliance at aortic root could be easily evaluated using non-invasive echocardiogram. In order to assess the compliance using echocardiography, we needed to know the sectional area changes of the aorta in a cardiac cycle. Firstly, these images reduced speckle noise of ultrasound by image processing. After that the edge contour of the aorta was tracked by active contour model (ACM). Finally, we calculated the sectional area changes of the aorta to estimate the aortic compliance. For verifying the accuracy of methods used in this study, we analyzed the relationship between left ventricular stroke volume and aortic flow by ten datasets of echocardiography, results showed a good correlation (R2=0.8837). To analyze the relationship between left ventricular volume and aortic sectional area in a cardiac cycle, the correlation coefficient was between 0.6 to 0.85, and showed the negative correlation. In addition, we were also to estimate the diameter of the aortic sectional area. The averaged maximum diameter of the aorta was 29.610±2.551 mm, and the averaged minimum was 24.609±2.715 mm. Mean difference between these two diameters was 5.001±1.148 mm. Finally, we estimated the aortic compliance using echocardiography with blood pressure from another three subjects, and the results were 0.021, 0.044 and 0.038 cm2/mmHg. This study proposed the method of image tracking and volume calculation had a good accuracy. Echocardiography can be used to estimate cardiovascular function.