Search

Presently the complete three-dimensional (3-D) reconstruction of the beating heart is only feasable with high-resolution, volumetric scanning devices [1,2], which in the present state of development are more suited for fundamental investigations than for routine clinical diagnostic purposes. However, projection images from a conventional biplane angiocardiographic x-ray equipment already include considerable 3-D information, which is intuitively conceived by the experienced cardiologist. In the future these equipments will be supplied increasingly with double C-arm units — allowing freely selectable orthogonal beam projections — and with digital image processing systems — allowing not only improved visualization of the injected contrast medium but in addition quantitative density measurements. These developments offer new possibilities for the objective assessment of the 3-D morphological information included in these multiplane angiocardiograms. To reconstruct an object from only a few views (say 2 to 6) it is necessary to incorporate a priori knowledge about its cross sections. Assuming that the object in each cross section has a constant grey level leads to binary reconstructions, which have been performed successfully for the 3-D reconstruction of coronary arterial segments from two projections [3], and for the reconstruction of the true shape of the left or right ventricular cavity [4].