MR flow imaging in projection through a stationary surround

A magnetic resonance imaging technique is discussed which, by cyclic inversion of the longitudinal magnetization, produces boli of moving material with alternating sign of the magnetization. At periodic spacings along the flow direction, the signal strength from magnetization of positive sign is equal to that of negative sign. This results in a minimum in the intensity distribution. A banded intensity structure results reflecting the distribution of flow velocities across the imaged vessel. The inversion of the longitudinal magnetization causes an inherent suppression of the signal from stationary material allowing the collection of flow images in projection through a stationary surround without the need for image subtraction.