1. A method for determining a degree of pulsatility from a sequence of images, comprising the steps of: acquiring ( 602. 6 ) with an imaging system a time intensity sequence of images ( 702 ) of the concentration of a known contrast agent resulting from transport of a mixture of blood and the known contrast agent through a vascular system of a patient; providing a contrast agent prediction model ( 707 ) that is based on a function of the mixing of the known contrast agent with an observed time-dependent blood flow; and extracting a degree of pulsatility from the acquired sequence of images ( 702 ) using the provided contrast agent prediction model.