In a method and control apparatus for tracking a contrast agent using an imaging medical device a test bolus of a contrast agent is initially injected into an examination subject, followed by an injection of a main bolus at a time interval of .DELTA.ti. The arrival of the test bolus in the observation volume is chronologically determined by periodically repeated survey measurements. An image data measurement is started at a time interval .DELTA.tm subsequent to the detection of the test bolus, this time interval .DELTA.tm being defined according to the prescribed time interval .DELTA.ti.