A method of predetermining the time profile of a contrast agent concentration at a vessel position is provided in the context of contrast agent-enhanced MRI of a region of interest only during the initial flooding-in phase of the contrast agent into the vessel situated in the region of interest. The method includes establishing a broadening of a contrast agent bolus profile according to the equation ΔW=W2−W1 wherein W1 is a first width of the contrast agent bolus profile at a first vessel position and W2 is a second width of a contrast agent concentration profile at a second vessel position within the region of interest. The broadening is established by determining at least one flow parameter which is dependent on at least one blood flow property of the patient at a third vessel position thereof and which correlates with the broadening of the contrast agent profile.