Spatial orientation of segments of the coronary arteries evaluated from 100 coronary angiograms

The mean spatial orientation of 10 predominant arterial segments of the coronary tree at end-diastole was determined from 100 routine coronary angiograms. The spatial orientation of an arterial segment was calculated from its projection images, acquired from biplane multidirectional isocentric X-ray systems. The theoretically optimal (orthogonal) radiographic projection of the X-ray system for each calculated mean orientation of a vessel segment was computed, and the adjustment of the X-ray system within its given freedom of movement was determined. The general capacity of the X-ray system for triple-orthogonal, double-orthogonal, and single-orthogonal radiographic imaging was tested. It is found that because the human coronary tree demonstrates a relatively narrow range of spatial orientation of each major coronary segment, the limited rotational capabilities of the X-ray stands partly restrict the achievement of triple orthogonal projections