Videodensitometric system for measurement of vessel blood flow, particularly in the coronary arteries, in man

Abstract

A system that allows the objective determination of blood flow in individual blood vessels (that is, coronary arteries) in intact man is described. Roentgenographic images (produced at a rate of 60/sec) are recorded on video tape before and during a single injection of radiopaque contrast material into the circulation and replayed any number of times. The dilution and dispersal of this contrast material can then be quantitatively determined from simultaneous indicatordilution (roentgen density) curves obtained from any site within the X-ray field by multiple roentgen videodensitometric analyses of the video tape record. Cyclic nonspecific changes in roentgen density due to motion of the vessel or catheter and changes in cardiac size and position are compensated for in real time measurements by digital computer. By obtaining the difference in mean transit times from indicator-dilution curves a measured distance apart along a coronary vessel, mean blood velocity can be determined and blood flow can then be calculated as the product of velocity and the vessel cross-sectional area obtained from biplane orthogonal roentgenograms. The effects of persisting contrast medium in the myocardium and cardiac chambers superposed in the videodensitometric sampling system are minimized by computer dynamic background cancellation techniques. Simultaneous determination of flow values in a canine "coronary" artery by roentgen videodensitometry and electromagnetic flowmeter show a good correlation (<i>r</i> = 0.95) among flow values of less than 150 ml/min. Similar coronary artery-roentgen density curves suitable for videodensitometric determination of flow have been obtained from clinical catheterization studies in man.