An angiographic method for measurement of absolute coronary blood flow in patients was developed. It is based on 3D-reconstruction of the left or right coronary tree from digitized biplane coronary cineangiograms. The apparatus is presently composed of a 35 mm cinefilm projector with a video camera and a 512 x 512 x 8 bits image array processor controlled by a VAX-11/750 computer. First, the parameters of the two angiographic projections are determined in form of two 4 x 3 matrices from a pair of cineframes showing a 4 cm cube bearing markers. The cube is filmed after the coronary injection, with unchanged geometric configuration. The coronary arteries of interest are then 3D-reconstructed from a pair of cineframes showing them fully opacified. This allows to compute the intravascular volumes needed for flow determination. In vitro experiments showed that the obtained volume are reasonably accurate. For the measurement of coronary flow, the concentration of contrast medium along the involved arteries is computed (in arbitrary units) from two cineframes taken one (or two) cardiac cycle after onset of the injection. This yields a 'concentration-distance' curve per artery. The volume of fluid (contrast medium mixed with blood) which flows into the arteries during this (or these two) cardiac cycle is determined by applying a concentration threshold to the obtained concentration-distance curves. Measurements performed on a constant flow model were satisfying. Preliminary measurements in 12 patients showed that flow values obtained angiographically into the left anterior descending coronary artery correlate well with the values measured simultaneously by thermodilution in the great cardiac vein (Qangio = 0.83 x Qthermo + 16.1 ml, r = 0.87, n = 29).
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A new method was developed to measure absolute coronary blood flow in all major branches of the coronary circulation using computer analysis of conventional biplane coronary cineangiograms.Coronary cineangiograms were obtained at SO fps in any biplane projections.A cube with IS radioopaque beads was filmed in the same projections. Images were digitized into a 512x512 8-bit matrix. From the biplane images of the cube and the known location of the beads, 2 projection matrices were calculated describing projection parameters f o r both planes. Arterial edges were determined by the computer for all branches > I mm in diameter. From the 2 projection matrices, the artery was reconstructed in 3 -0 and its true volume calculated. Absolute flow was given by the coronary volume filled by contrast medium during the first cycle following the injection divided by the duration of that cycle.A good correlation was found between absolute flow in the LAD by this technique and great cardiac vein flow simultaneously measured by thermodilution in patients at baseline and during pacing-induced hyperemia (r = 0.82 and SEE = 9.8 mllmin). . IntroductionCoronary angiography provides important information on the location and severity of a coronary stenosis, but does not provide any information on its physiologic a1In the past few years, several groups have attempted to assess the physiological sign i fic anc e. significance of a coronary stenosis by measuring coronary flow reserve using computer analysis of coronary angiograms [l]. However, flow reserve is a relative index that depends on the level of resting flow and the achievement of maximal hyperemia [2]. Resting flow is influenced by a number of factors including the presence of LV hypertrophy, contractility, tachycardia, aortic and LV diastolic pressure. On the other hand, absolute coronary flow takes into account all factors affecting resting flow and does not depend on achieving maximal vasodilation.Several years ago, Rutishauser et al. determined absolute coronary flow by measuring the transit time of a contrast bolus between 2 points in a right coronary artery [3, 41. However, this approach was limited to large, proximal, non branching arteries parallel to the image intensifier.We extended this approach to measure absolute coronary blood flow in ml/min in all major branches of the coronary circulation using computer analysis of conventional coronary cineangiograms. . M e t h o dOur method has been described elsewhere in details [ 5 ] . Briefly, a conventional coronary cineangiogram is obtained in any biplane projections at 50 frames/sec by manual injection of 6-8 ml iopamidol. A 4 cm cube is filmed in the same biplane projections. This cube has 15 radioopaque beads placed at each comer, in the middle of each side and in the tenter. Images are digitized into a 512x512 8-bit matrix. From the biplane images of the 721 0-8186-2485-x192 $3.00 0 1992 IEEE
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