AORTIC AND HEPATIC CONTRAST-MEDIUM ENHANCEMENT AT CT PART-II - EFFECTOF REDUCED CARDIAC-OUTPUT IN A PORCINE MODEL

PURPOSE: To investigate how reduction in cardiac output affects the ma gnitude and timing of aortic and hepatic contrast medium enhancement d uring abdominal computed tomography (CT). MATERIALS AND METHODS: Eight 20-30-kg pigs underwent CT before and after pharmacological reduction of cardiac output (measured by means of thermodilution). Each CT stud y consisted of 53 dynamic images acquired every 5 seconds at a fixed l evel through the midliver after intravenous injection of contrast medi um (concentration, 282 mg of iodine per milliliter; dose, 2 mL per kil ogram of body weight; injection rate, 2 mL/sec). Curves of contrast me dium enhancement versus time were measured. Changes in the magnitude a nd timing of aortic and hepatic enhancement were compared with the red uction in cardiac output. RESULTS: With the reduction in cardiac outpu t, the time from the injection start to the arrival of the contrast me dium bolus in the aorta (P < .01) and the times from injection complet ion to peak aortic (P < .01) and peak hepatic (P < .01) enhancement in creased. As cardiac output decreased, peak aortic enhancement increase d proportionally (P < .01). Peak hepatic enhancement increased only sl ightly and correlated weakly with the decrease in cardiac output (P = .07). CONCLUSION: As cardiac output decreases, the times to the arriva l of the contrast medium bolus in the aorta and to peak aortic and hep atic enhancement increase. Reduction in cardiac output results in a su bstantial increase in peak aortic enhancement but not in peak hepatic enhancement.