title: FID-SPI pulse sequence for quantitative MRI of fluids in porous media.
abstract: MRI has great potential for providing quantitative, spatially resolved information about fluids imbibed in porous media. The pure phase encode SPRITE technique has proven to be a very general method for the generation of density images in porous media; however, low flip-angle RF pulses and broad filter widths, required by short encoding times, yield sub-optimal S/N images. A 1-D phase-encoding sequence for T2(∗) mapping, named FID-SPI, is presented and analyzed in terms of image quality and accuracy of fluid content distribution in porous media. Extension to 2-D and 3-D imaging was straightforward and images of heterogeneous samples are presented. The FID-SPI measurement results in a series of individual T2(∗) weighted images acquired following RF excitation and pulsed phase-encoding gradients. Key to the performance of the FID-SPI method is high quality control of the magnetic field gradient pulse to ensure each FID point has identical spatial encoding. FID-SPI is intended for a quantitative determination of the spatially resolved fluid content in heterogeneous porous media, having the ability to determine the T2(∗) decay for each image pixel. T2(∗) mapping aids in estimation of the local fluid content.
authors: MRI Research Centre, Department of Physics, University of New Brunswick, 8 Bailey Drive, Fredericton, NB E3B 5A3, Canada. Electronic address: fmarica@unb.ca.
authors: Florea
authors: F
authors: Marica
authors: MRI Research Centre, Department of Physics, University of New Brunswick, 8 Bailey Drive, Fredericton, NB E3B 5A3, Canada.
authors: Frédéric G
authors: FG
authors: Goora
authors: MRI Research Centre, Department of Physics, University of New Brunswick, 8 Bailey Drive, Fredericton, NB E3B 5A3, Canada.
authors: Bruce J
authors: BJ
authors: Balcom
keywords: Density imaging; FID-SPI; Fluids; Free induction decay single point imaging; Phase-encoding MRI; Porous media; distribution