Quantitative assessment of Arterial Blood Flow Measurement by Digital Subtraction Angiography

通过数字减影血管造影（DSA）测量平均血流量、平均传递时间和血管体积。血管造影设备为philips生产的DVI-II型。图像序列以矩阵512 × 512像素，频率为30帧/秒。造影剂的传递时间确定为在血管近端和远端测量的两个时间密度曲线（TDC）之间的时间。通过插值将背景校正后的TDC转换为300点/秒。在连续流动和脉动流动的循环模型中，研究了数字密度测量流量与实际流量的关系。相对于峰值法（以出现时间作为TDC的峰值点）、峰值1/2法（在TDC的领先斜率达到最大值的一半时取出现时间）和平均法（TDC的第一次矩），互相关法可能有很好的应用。互相关法中，连续流（r=0.98）与脉动流（r=0.95）具有较好的相关性。理论上我们系统的最佳空间分辨率为0.15mm。为了获得这一分辨率，我们采用了选择性注射未稀释的造影剂，管电位为70 kv，图像增强器直径为6.5英寸，基于实验使用的幻影，由一个直径为0.5mm至7.0mm的光阑钻孔的萤光石板组成。我们的方法测量了人冠状动脉旁路移植术的血流。7例（7例）平均体表面积为1.63+-0.17m^2的移植物平均流量为40.7+-11.5 ml/min。该值与以前报告的结果一致。经心房起搏后，移植物生长明显增加（p<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).