Barfett Joseph John, Velauthapillai Nivethan, Fierstra Jorn, Crawley Adrian, Coolens Catherine, Crean Andrew, Jaskolka Jeff, Dufort Paul, Krings Timo, Mikulis David
Department of Medical Imaging, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada,
Int J Cardiovasc Imaging. 2014 Oct;30(7):1383-92. doi: 10.1007/s10554-014-0471-3. Epub 2014 Jul 8.
We examine a time of flight (TOF) approach for the analysis of contrast enhanced 4D volumetric CT angiography scans to derive and display blood velocity in arteries. Software was written to divide blood vessels into a series of cross sections and to track contrast bolus TOF along the central vessel axis, which was defined by a user, from 4D CT source data. Time density curves at each vessel cross section were fit with quadratic, Gaussian, and gamma variate functions to determine bolus time to peak (TTP). A straight line was used to plot TTP versus vessel path length for all three functions and the slope used to calculate intraluminal velocity. Software was validated in a simulated square channel and non-pulsatile flow phantom prior to the calculation of blood velocity in the major cerebral arteries of 8 normal patients. The TOF algorithm correctly calculates intra-luminal fluid velocity in eight flow conditions of the CT flow phantom where quadratic functions were used. Across all conditions, in phantoms and in vivo, the success of calculations depended strongly on having a sufficiently long path length to make measurements and avoiding venous contamination. Total blood flow into the brain was approximately 17 % of a normal 5 L cardiac output. The technique was explored in vivo in a patient with subclavian steal syndrome, in the pulmonary arteries and in the iliac artery from clinical 4D CT source data. Intravascular blood velocity and flow may be calculated from 4D CT angiography using a TOF approach.
我们研究了一种飞行时间（TOF）方法，用于分析对比增强的4D容积CT血管造影扫描，以得出并显示动脉中的血流速度。编写了软件，用于将血管划分为一系列横截面，并从4D CT源数据中沿着用户定义的中心血管轴追踪对比剂团注的TOF。对每个血管横截面的时间密度曲线进行二次函数、高斯函数和伽马变异函数拟合，以确定团注到达峰值的时间（TTP）。使用一条直线绘制所有三个函数的TTP与血管路径长度的关系图，并使用斜率计算管腔内速度。在计算8名正常患者大脑主要动脉的血流速度之前，该软件在模拟方形通道和非搏动性流动模型中进行了验证。在使用二次函数的CT流动模型的八种流动条件下，TOF算法正确计算了管腔内液体速度。在所有条件下，无论是在模型中还是在体内，计算的成功很大程度上取决于有足够长的路径长度进行测量并避免静脉污染。流入大脑的总血流量约为正常5L心输出量的17%。利用临床4D CT源数据，在一名患有锁骨下动脉盗血综合征的患者体内、肺动脉和髂动脉中对该技术进行了研究。使用TOF方法可以从4D CT血管造影中计算血管内血流速度和流量。
