Quantitative assessment of Arterial Blood Flow Measurement by Digital Subtraction Angiography

采用数字减影血管造影术(DSA)测量平均血流量、平均通过时间和血管容量。血管造影设备为飞利浦公司生产的DVI-II。以30帧/秒的频率获得具有512×512像素的矩阵的图像序列。造影剂通过时间确定为在血管近端和远端测量的两条时间密度曲线(TDC)之间的时间。通过内插将背景校正后的TDC转换为300点/秒。在连续流动和脉动流动的循环模型中，考察了数字密度测量流量与实际流量之间的关系。与峰值法(以出现时间作为TDC的峰值)、峰1/2法(出现时间取TDC的前斜率的一半)和平均法(TDC的一阶矩)相比，互相关法可能具有很好的应用价值。在互相关法中，连续流(r=0.98)和脉动流(r=0.95)都获得了很好的相关性，理论上最好的空间分辨率为0.15 mm。为了获得这一分辨率，我们采用了选择性注入未稀释的造影剂，管电位为70KV，并用直径6.5英寸的像增强器放大图像，基于使用体模的实验，该体模由一个直径为0.5 mm~7.0 mm的荧光板组成。7例(7例)移植血管平均体表面积为1.63±0.17m^2，平均流量为40.7±11.5ml/min。这一数值与之前报告的结果一致。在心房起搏时，移植物宽度显著增加(p&lt；0.01)。

The mean blood flow was measured with mean transit time and vascular volume by digital subtraction angiography(DSA). The angiographic equipment is DVI-II of phillips manufacture. Image series are aquired with a matrix 512 x 512 pixels at a frequency 30 frames/sec. Transit time of contrast medium is determined as the time between two time density curves(TDC) measured at a proximal and a distal site of the vessel. Back-ground corrected TDC is transformed to 300 points/sec by interpolation. The relation between digital densitometrically measured flow and actual flow was examined in a circulatory model ith continuous as well as pulsatile flow. Compared with peak method (appearance time is taken as peak point of TDC),peak 1/2 method(appearance time is taken when leading slope of TDC reaches half the maximum) and average method(first moment of TDC),cross-correlation method may have excellent applications. In cross-correlation method, good correlation was obtained in continuous flow(r=0.98) and in pulsatile flow(r=0.95).Theoretical best spatial resolution in our system is 0.15mm. To obtain this resolution,we employ selective injection of undiluted contrast media,tube potential of 70 kv and magnified image by 6.5 inch diameter image intensifier,based on experiment using the phantom,consisted of a lucite plate with drilled lumina ranging from 0.5mm to 7.0mm in diameter. The flow through aorto-coronary bypass graft was measured in man with our method.mean flow in 7 grafts(7 patients) with a mean body surface area of 1.63+-0.17m^2 amounted to 40.7+-11.5 ml/min. This value is consistent with the results of previous reports. By atrial pacing,graft frow increased significantly( p<0.01).