In patients with coronary artery disease coronary angiography plays an important role in the clinical decision-making process. However, it has been recognized that no simple relation exists between the visually or quantitatively evaluated severity of coronary artery stenoses and its effects on regional myocardial perfusion. This paper describes for the first time the development and application of a 3D technique that visualizes and quantifies regional myocardial perfusion parameters from biplane coronary angiograms by using the impulse response analysis technique. The 3D reconstructed coronary tree is automatically superimposed on the 3D perfusion image to generate and visualize an 'integrated' 3D image. The preliminary results in patients with critical coronary artery stenoses indicate that our combined 3D fusion image provides flow information from the major coronary arteries. This 3D fusion image may provide useful information in the management of patients with coronary artery disease.

One of the major objectives in angiocardiography is the visualization of anatomical details of a vessel segment of interest. The excellent resolution of the cinefilm can't be reproduced by today's digital systems. A universal compromise between image quality and strong data reduction is difficult to find. Here the authors propose the concept of image content descriptions as related parameters to be stored with(in) the image. The image frame is divided into regions of different medical significance allowing different degrees of data reduction and quality enhancement. This concept is illustrated by several examples: the 3D-reconstruction avoids unnecessary data, the motion compensated loop preserves the film resolution in critical regions, and the predictor-corrector postprocessor, tunes an arbitrary lossy compressor to become partially nonlossy in the most important regions of the image.

Using a biplane multidirectional isocentric X-ray system, a computer-aided simulation procedure was developed to calculate the 3D structure of the coronary arteries. The algorithm uses the geometry of the biplane X-ray system and the alignments of corresponding points of the coronary arteries in two X-ray images acquired under different viewing angles. The identification of the corresponding points is greatly simplified by the calculation and display of the intersection lines of the confocal plane with the image intensifier entrances on the computer monitor. To minimize the total number of necessary corresponding points we used Bézier curves to match the courses of the coronary segments between neighboring corresponding points. The projection of the calculated 3D structure was found to be in very good agreement with the 2D course of the coronary arteries in the angiograms. The 3D structure can be viewed on the computer screen under any desired simulated projection angle within the geometrical limitation of the X-ray gantries. The user can select views on the computer monitor with orthogonal projection angles and minimal overlapping problems caused by under- and overlying structures. The method was applied in 10 cases of elective angioplasty. Previously taken diagnostic angiograms were used to reconstruct the arterial structure and to select favorable views for the forthcoming intervention.

The authors designed a method to reconstruct and visualize the coronary tree from one biplane angiogram by modeling a 3-D Bezier curve to the 3-D structure of the coronary arteries. The start and end points of the single Bezier curves in one image have corresponding points in the other image. To facilitate the choice of the corresponding points the projection of the confocal plane is displayed in both images. The operator aligns 2-D Bezier curves with the vessel segment in both images. The program automatically adjusts the curve in the second image, maintaining a constant projection of the same 3-D Bezier curve. A corresponding 3-D Bezier function is well defined by the alignments of these 2-D Bezier functions with the coronary arteries and vice versa. The interactive procedure was designed to optimize the time for a reliable coronary tree reconstruction.< >

The authors designed a method to quantify and visualize regional myocardial perfusion in routine coronary angiograms. Regional time density curves were acquired over the proximal coronary arteries and the myocardial microcirculation. Impulse response analysis was applied to determine the resting mean transit time of contrast material to traverse the microcirculation. Using biplane coronary angiograms the 3-D structure of the coronary tree can be calculated. The surface of an ellipsoid can be fitted to the 3-D structure of the coronary arteries representing the epicardial surface of the heart. The values of the measured mean transit times were aligned to corresponding positions on the epicardial surface of the heart. These images allow separation of myocardial regions with different perfusion characteristics