Quantitative angiographic blood-flow measurement using pulsed intra-arterial injection

A technique for quantitative blood-flow measurement using a novel pulsed in jection of radiographic contrast agent is reported. A pressurized source of contrast agent is interrupted by a rotary valve at rates ranging from 1 to 30 Hz, producing well-defined boli at the end of a catheter. The position of these boli can be recorded by a digital radiographic system and analyzed by one of several previously reported techniques, to produce quantitative measurements of blood velocity and how rate throughout the cardiac cycle. T he contrast-agent flow wave form produced by the pulsed injector has been m easured with an electromagnetic how meter, for driving pressures ranging fr om 600 to 1500 kPa. Excellent modulation of the contrast agent is observed for injection frequencies up to 20 Hz, through catheters up to 100 cm in le ngth, Preliminary in vitro angiographic flow measurements have been perform ed using an x-ray image intensifier, coupled to a linear photodiode array a s the digital detector. Both constant flow and pulsatile human blood-flow w ave forms were simulated within a 6.4-mm-diam straight tube and monitored w ith an electromagnetic flow meter. These experiments indicate that the puls ed injector can be used to provide estimates of arterial blood flow over th e entire cardiac cycle (including reverse flow), to within about +/-11%, fo llowing injection of less than 10 ml of iodinated contrast agent. (C) 1999 American Association of Physicists in Medicine. [S0094-2405(99)00410-1].