計算流體力學在心血管系統模擬與冠狀動脈狹窄程度判讀的應用

Abstract

血流儲備分數（fractional flow reserve, FFR）為評估冠狀動脈狹窄程度和支持臨床決策的關鍵指標。本研究應用了基於放射學圖像的血液動力學建模和計算流體力學（computational fluid dynamics, CFD）方法來模擬冠狀動脈壓力分佈，並以此來判斷心肌缺血之可能性。模擬過程中，冠狀動脈血液流速為重要邊界條件，本研究使用四種不同方式來推估血管內質量流率 – 固定流速、由阻力表推估、依據冠狀動脈血管攝影(coronary angiogram, CAG)之影像幀數、依據左心肌與血管大小推估，本研究分別將此四種方式所得之流速搭配電腦斷層冠狀動脈血管攝影（coronary computed tomography angiography, CCTA）提供之冠狀動脈幾何模型，進行血管內壓力場模擬，並計算出血流儲備分數之數值。其中考慮左心肌與血管大小推估之邊界條件，有著最大的AUC值，可以達到最好的分類效果，且此模擬數據與心臟導管檢查數據也最為接近。

Fractional flow reserve (FFR) is a crucial index to evaluate the severity of stenosis in coronary arteries and to support clinical decisions. The study applied radiology image-based hemodynamic modeling and computational fluid dynamic (CFD) methods to simulate the distribution of coronary arterial pressure and to evaluate the likelihood of myocardial ischemia. During the simulation process, the mass flow rate of the blood in coronary arteries is one of the most important boundary conditions. This study uses four methods to estimate the mass flow rate – assuming fixed distal velocity, pre-interventional resistance table, computed angiography (CAG) frame counts, and the values derived from left ventricular and coronary arterial sizes. With the geometrical information of coronary arteries and the myocardium extracted from coronary computed tomography angiography (CCTA), the pressure field and the value of FFR can be derived. Among all of these methods, mass flow rate considering the myocardium and artery size can yield the best result, whose AUC is the biggest among the four methods and the FFR values are also the closest to the catheterized FFR values.