4570119 Method for visualization of in-plane fluid flow by proton NMR imaging

Abstract

A method for visualizing in-plane flow utilizing an NMR pulse sequence to produce a plurality of odd and even spin-echo signals occurring respectively at echo delay times, T E , of 2τ, 6τ, 10τ, etc., and 4t, 8τ, 12 T , etc. In the preferred embodiment, a fictitious spin-echo amplitude is calculated from the odd and even spin-echo signals at an echo delay time T E = 0, for example. The calculated values for the odd spin-echo signals are lower than those calculated for the even spin-echo signals due to incomplete rephasing of the odd spin-echo signals in the presence of a read-out magnetic field gradient and flow. Subtraction of the calculated image pixel value of the odd spin-echo signals from the calculated pixel values of the even spin-echo signals results in a difference image which highlights the flowing nuclear spins. The image pixels due to stationary nuclear spins experience exact cancellation.