BLOOD VELOCITY DETERMINATION

A method is provided for estimating blood velocity in vessel, for example for use in deriving a measure of blood flow through the vessel. The method comprises two stages. In a first stage, multiple measurements of blood velocity are acquired, using ultrasound data, at different radial positions across a blood vessel cross-section. A velocity profile is determined (velocity as a function of measurement location across the vessel cross-section) based on this. In a second stage, in one or more subsequent cardiac cycles, new ultrasound data is acquired and a blood velocity measurement acquired at a single location. The single blood velocity measurement preferably corresponds to a location of maximum velocity. This single measurement, in combination with the personalized velocity profile already derived, is used to derive a measure of average blood velocity within the vessel.