Purpose: To determine the temporal variability of the time to maximum aortic density after peripheral venous contrast injection in cardiovascular CT studies and to calculate potential contrast agent savings of selecting scan delay from test bolus kinetics.
Methods: A peripheral contrast bolus was administered intravenously in 138 consecutive patients to determine the time to maximum density in a left ventricular or aortic region of interest by electron beam CT. 20 EKG-triggered scans were acquired within 70 heartbeats. The deviation of the time to maximum density from a standard, fixed scan delay was determined.
Results: Mean time to maximum density was 22 s, and the average deviation from that mean was 5 s. At an injection rate of 4 cc/s, this deviation implies that determining the individual scan delay from a test bolus injection may potentially save 20 cc contrast per patient. This amount of contrast agent, in turn, is required for the test bolus.
Conclusion: Deriving the individual scan delay from test bolus kinetics may improve image contrast in cardiovascular CT studies without additional contrast expense.