Computer enhanced digital angiography

A new computer image enhancement technique was employed on cardiac images of 10 dogs and 7 patients to demonstrate the feasibility of an on‐line automatic delineation of the left ventricular endocardial silhouette with a peripheral venous injection of contrast material while simultaneously reducing the x‐ray dosage. This technique employs a very fast analog‐to‐digital conversion system capable of digitizing on‐line video frames. By storing and continuously updating the first 30 video frames and then subtracting each incoming frame from this memory, most of the background is eliminated leaving only the contrast filled ventricle. Using calibrated densitometric measurements, we found that iodine concentrations in the human left ventricle following venous injection of 40 ml Renografin®‐76 (25 ml/s), peaked at 4.3±0.3 mg/ml (mean±SD) compared to 14.8±0.8 mg/ml following direct injection of 40 ml at 13 ml/s (p