Evaluation of Roentgen Cinedensitometry for Flow Measurement in Models and in the Intact Circulation

The flow of blood in vitro and in the carotid artery of the dog was calculated by a new cinedensitometric technique and compared with the flow as measured simultaneously by graduated cylinder and stopwatch. Cineangiographic films were projected onto a frosted screen and the light intensity was measured at two neighboring cross sections of the vessel in question. The passage of the contrast medium yielded a pair of indicator-dilution curves of which the difference in mean transit time was calculated. The distance between the cross sections and the diameter of the vessel was measured with the aid of x-ray-dense scales. The flow through the vessel was calculated as the product of cross-sectional area and mean velocity. The correlation coefficient between the volumetric flow and the flow as found by cinedensitometry was 0.976 in vitro and 0.946 in the intact dog with no systematic deviation from the line of identity. The method enables the blood flow in the intact circulation to be calculated in milliliters per second in any vessel that can be clearly visualized by cineangiocardiography.