Aortic and hepatic contrast medium enhancement at CT. Part II. Effect of reduced cardiac output in a porcine model.

PURPOSE: To investigate how reduction in cardiac output affects the magnitude and timing of aortic and hepatic contrast medium enhancement during abdominal computed tomography (CT).
MATERIALS AND METHODS: Eight 20-30-kg pigs underwent CT before and after pharmacologic reduction of cardiac output (measured by means of thermodilution). Each CT study consisted of 53 dynamic images acquired every 5 seconds at a fixed level through the midliver after intravenous injection of contrast medium (concentration, 282 mg of iodine per milliliter; dose, 2 mL per kilogram of body weight; injection rate, 2 mL/sec). Curves of contrast medium enhancement versus time were measured. Changes in the magnitude and timing of aortic and hepatic enhancement were compared with the reduction in cardiac output.
RESULTS: With reduction in cardiac output, the time from the injection start to the arrival of the contrast medium bolus in the aorta (P < .01) and the times from injection completion to peak aortic (P < .01) and peak hepatic (P < .01) enhancement increased. As cardiac output decreased, peak aortic enhancement increased proportionally (P < .01). Peak hepatic enhancement increased only slightly and correlated weakly with the decrease in cardiac output (P = .07).
CONCLUSION: As cardiac output decreases, the times to the arrival of the contrast medium bolus in the aorta and to peak aortic and hepatic enhancement increase. Reduction in cardiac output results in a substantial increase in peak aortic enhancement but not in peak hepatic enhancement.