Evaluation of Roentgen cinedensitometry for flow measurement in models and in the intact circulation.

SUMMARY 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. Mean circulation time Blood velocity Blood flow pattern Carotid flow Contrast medium for blood flow determination ANGIOCARDIOGRAPHY has been studied widely from the point of view of its morphological applications. Until recently, however, only a few attempts had been made to utilize the injection of contrast media for quantitative flow studies of the circulation.1-5 To the knowledge of the present writers, Wood and his group were the first to recognize the functional potential of angiocardiog-raphy as an indicator-dilution method. They worked first with the film and subsequently with the television technique."-The experiments described in the present paper were designed to study the reliability of blood flow measurements using a cine-densitometric technique. Angiographic films were projected, and the light intensity was recorded at selected sites during the passage of the contrast medium. The envelope of the observed light intensity versus time curve corresponds to an indicator-dilution curve. The flow was calculated as the product of mean velocity (that is, the distance between two cross sections divided by the mean transit time) and the cross-sectional area of the vessel. The rates of flow thus determined were compared with those found with the aid of a calibrated cylinder and stopwatch in both the vitro and the in vivo experiments.