MR flow measurement by a flowing slice selection

Magnetic resonance imaging of flow by successive excitation of a moving slice is presented. The method is based on selectively changing the frequencies in a sequence of RF pulses in such a way that a selected slice moves through the imaged volume with a preselected direction and velocity and is repeatedly excited. Most of the measured signal comes only from those parts of the imaged substance which move with the selected slice. The procedure for activating the flowing spins, which is described, enhances the image of the flowing matter and reduces the signal from static matter. A specially tailored sequence of RF α-pulses has been devised. During this sequence, a set of 180° selective rephasing RF pulses is applied. At the end of this sequence an additional 180° selective RF pulse is applied to eliminate redundant signals from the static matter in the last activated slice