Quantitative assessment of Arterial Blood Flow Measurement by Digital Subtraction Angiography

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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).