Intravenous angiocardiography using digital image processing: I. Experience with axial projections in normal pigs.

Computerized digitization and processing of roentgen video images was performed in four-chamber-view intravenous angiocardiography in normal pigs. Significant contrast enhancement was obtained through electrocardiogram-gated background subtraction and rescaling after integration of multiple background and contrast images. Histogram equalization and time parameter extraction or functional imaging was also used. The left and right heart were well visualized after intravenous injection of 0.5-1 ml Urografin-76% per kg of body weight. Image processing of left and right ventricular end diastolic and end systolic frames was performed as well as subtraction of right and left end systolic from end diastolic frames and subtraction of right from left heart frames. If left ventricular end systolic images were subtracted from end diastolic images, the left ventricle was seen without continuity with the left atrium. Through time interval difference processing, left ventricular wall motion per time unit could be studied. The results were the basis for subsequent experiments concerning detection of septal defects in pigs as well as clinical studies.