利用心臟電腦斷層影像評估動脈脈搏傳導速度

Estimation of Pulse Wave Velocity using Cardiac Computer Tomography Image

陳奕瑋(Yi-Wei Chen)

指導教授 ： 胡威志

中原大學/工學院/生物醫學工程研究所/碩士(2012年)

https://doi.org/10.6840/cycu201200130

摘要

動脈總順應性(total arterial compliance,TAC)是指全身動脈順應性之總和，通常只有接近心臟、具有彈性之大動脈的順應性，可用來評估全身動脈血管硬化程度，臨床上大多以脈波傳導速率(Pulse Wave Velocity , PWV)做為動脈總順應性之相關參考指標。為了能精確的評估血管硬化程度，脈波傳導速率的評估更顯重要。
本研究的目的是觀察主動脈在心週期下的容積變化來評估動脈脈搏傳導速度(PWV)，利用多個時序的心臟電腦斷層影像(computed tomography,CT)的特性針對主動脈部位的觀察與分析，首先將CT影像資訊建構成3D立體影像後手動重新校正中心軸的角度再做重新取樣的動作，並且對重新取樣後的影像用2D的旋轉公式做定位的校正，接著觀察主動脈在整個胸腔內的生理位置並以動態邊緣(active contour: snake)和區域成長(seeded region grow)兩個方法尋找出主動脈的邊緣輪廓，運算出主動脈的容積大小並分析主動脈脈搏傳導速度參數。脈搏傳導速度是由兩個不同主動脈量測位置面積或容積值所形成的波形，於同一心動週期相同參考點的時間差與兩個量測位置距離之比值，所得到的血管硬化程度參考指標。
實驗部分利用15位受測者以本研究所計算出的容積參數，分成容積驗證與主動脈脈搏傳導速度相關性與差異度的分析，其一為左心室心搏量與主動脈流量驗證，藉由每一個心週期下左心室心輸出量相等於主動脈流量的原理來驗證本研究所使用左心室與主動脈容積圈選方法的準確性，結果顯示本研究估算之左心室心輸出量與主動脈截面積流量之間關係呈現正相關(R=0.970，P<0.01)，其二為評估脈搏傳導速度與其他血管硬化參數指標的相關性討論。結果顯示本研究所評估的脈搏傳導速度與動脈順應性相關性分析結果成正相關(R=0.672，P<0.01)、與血管擴張性相關性結果成負相關(R=-0.8549，P<0.01)、與年齡相關性結果呈正相關(R=0.794、P<0.01)，本研究提供一套利用非侵入式的電腦斷層影像中藉由主動脈容積變化估算主動脈脈搏傳導速度

關鍵字

心臟斷層影像 ； 區域成長 ； 動態邊緣 ； 脈波傳導速率

並列摘要

Recent studies have shown that patients who have atherosclerosis would increase the risk of cardiovascular disease directly or indirectly. Total arterial compliance (TAC) is defined as the sum of systemic arterial compliance, and assessment of compliance for artery stiffness was usually used central aorta which is more elasticity than peripheral and closes to the heart. Pulse wave velocity (PWV) is an index for assessing the level of artery stiffness in clinic.
The purpose of this study is to observe the volume changes in the aortic heart cycle to evaluate the arterial PWV. Observation and analysis of the cardiac computed tomography images of multiple timing characteristics for aortic parts. firstly, the reposition of the left ventricle in short axis view, the central axis of the 3D LV model was adjusted manually to be aligned with axis that was constructed using central point of short axis LV image from mitral valve to the apex of left ventricle. 2D Rotation formula for correctly positioning and image re-sampling. Then observe the physical location of the aorta in the chest. The active contour and the seeded region grow are two function to locate the edge contour of the aorta. Calculate the volume of the aorta to analyze the aortic PWV parameters. Pulse wave velocity is two waveforms formed by two different measurement positions of aortic of the area or volume. Considering a common reference point in the same cardiac cycle for the ratio of the difference in time between the difference in distance.
This experiment utilized fifteen people to calculate the volume parameter. The volume verification and the aortic pulse conduction velocity differs with the degree of analysis. One verified the left ventricular stroke volume and the aorta flow, the left ventricular cardiac output is equal to the principle of the aortic flow in each heart cycle. To verify the accuracy of the left ventricular and aortic volume method used in this study, results shows that the relationship between the estimation of the left ventricular cardiac output of this study and the aortic cross-sectional area of flow is positive correlation (R = 0.970, P <0.01). Pulse Wave Velocity was the correlation with other vessel stiffness parameters and result showed that pulse wave velocity and arterial compliance were positive correlated (R=0.672，P<0.01) and the relation with dispensability was negative correlated (R=-0.8549，P<0.01) but the age was positive correlated (R=0.794、P<0.01).This study provides a use of non-invasive computed tomography image through the aortic volume change to assessment of aortic pulse wave velocity

並列關鍵字

seeded region grow ； active contour ； CT image ； pulse wave velocity

參考文獻

[14] 李佳融，“半自動式左心室三維動態模型之運動和形態分析系統”，中原大學醫學工程所，碩士學位， 2002。

[16] 吳明鴻，“利用心臟電腦斷層影像評估左心房與左心耳之射血功能”，中原大學醫學工程所，碩士學位，2007。

[17] 翁政軒，“心房運動功能評估之工具發展”，中原大學醫學工程所，碩士學位，2008

[18] 馬銘徽，“建構左心室四維動態模擬工具評估左心室心肌運動功能”，中原大學醫學工程所，碩士學位，2010。

[1] M. Kass, A. Witkin, D. Terzopoulos（1987）：‘Snakes: Active Contour Models ’，International Journal of Computer Vision, on page 321-331