Differential flow imaging by NMR

Abstract

A new method for spatially resolved NMR flow measurements, named differential flow imaging (DFI), is introduced and experimentally verified. The DFI technique is based on the fact that flow velocity in any direction may cause a pixel position shift in the phase-encoding direction of a 2DFT NMR image. In this method two flow-influenced magnitude images are obtained by properly encoding and/or compensating the flow velocity. A spatial map of the desired component of the flow velocity can consequently be calculated from these two images. Since the DFI technique uses only the magnitude information of the complex images, it is not sensitive to systematic phase errors in contrast to other methods which are based on the phase measurements. On the other hand, the DFI technique can be combined with the phase measurement methods to perform multidimensional flow measurements in a shorter data acquisition time when the phase errors are small or corrected.