Coronary angiographic examination with the dynamic spatial reconstructor

The dynamic spatial reconstructor (DSR), a high temporal resolution, three-dimensional roentgenographic, computed tomography scanner, was used to scan the coronary arteries of five dogs. After one injection of contrast medium into the left main coronary artery or into the aortic root of each dog, all major epicardial coronary arteries and the septal artery could be imaged. After selective removal of nonangiographically enhanced anatomic structures with the three-dimensional images, pseudo three-dimensional displays were generated to show the arteries from all possible views - even the strictly cranial view - so that superposition of arteries could be evoked. The geometric accuracy of the images was evaluated by comparing coronary arterial segment length measured by the DSR with postmortem measurements (r = .99, SEE = 3.12 min. n = 35) and by measuring the stenosis produced by nine hollow plastic cylinders lodged in coronary arterial lumina via percutaneous catheterization. Three of the plugs had irregular noncircular lumina drilled into them so that the percentage of stenosis seen in some projection images underestimated the severity of stenosis. The DSR overestimated the length of a 3 mm long stenosis by 0.4 ± 0.5 mm. The percent area reduction caused by hollow cylinders varied between 53% and 92% and was underestimated by the DSR on the average by 7%. The correlation between DSR measurements and the direct measurements was r = .85 (SEE = 5%, n = 9). The volume of plastic in each plug (average 13.2 mm³), calculated from the length, cross-sectional area, and degree of the stenosis, showed a better correlation (r = .90, SEE = 2 mm³) with the actual plastic volume. The regression line showed no significant differences from the line of identity (p > .05), indicating that overstimulation of length of stenosis and underestimation of degree of stenosis canceled each other out. Area measurements of the same three stenosed segments after selective coronary and a consecutive aortic root injection showed good reproducibility of DSR measurements (r = .95). Values for stenotic length differed by only 0.1 mm and those for plastic volume by only less than 1.5 mm³ in all three cases.