In a method and magnetic resonance apparatus to acquire diagnostic image data of a contrast agent-filled target area of a patient, a peak time of the test bolus in the target area is automatically determined, from which a wait period is then determined for administering the main bolus. After the main bolus has been administered to the patient, magnetic resonance images of the target area are acquired, and each is analyzed immediately after acquisition thereof to determine whether that image shows arrival of the contrast agent. If and when one of these images shows such arrival, an acquisition protocol is immediately started in order to acquire the diagnostic image data set. If none of these images shows arrival of the contrast agent, the protocol to acquire diagnostic image data is started after the wait period.