title: T2selective π Echo-Planar Imaging for porous media MRI.
abstract: The π Echo Planar Imaging (PEPI) method has recently been modified to permit proton density imaging of fluids in porous media with moderate T2and short T2∗signal components. In many applications, it is desirable to discriminate multiple T2components within each image voxel. T2selective imaging is explored in this paper through adiabatic inversion as a magnetization preparation with PEPI readout. When prior information of the sample relaxation times is known, responses of different species to broadband adiabatic inversion pulses can be predicted by Bloch equation simulation. Different relaxation components can be acquired by combining the images with and without inversion preparation pulses. T2weighting can be easily introduced in the PEPI sequence by shifting the spatial encoding gradients based on its spin echo nature. T2decay curves can be extracted for each image voxel from a series of T2weighted images and spatially resolved T2distributions can be generated. This method is reliable but slow. The two methods were implemented to image porous media samples with PEPI the common basis of spatial resolution. The results of both methods agree remarkably well.
authors.affiliation: MRI Research Center, Department of Physics, University of New Brunswick, 8 Bailey Drive, Fredericton NB E3B 5A3, Canada. Electronic address: d.x@unb.ca.
authors.forename: Dan
authors.initials: D
authors.lastname: Xiao
authors.affiliation: MRI Research Center, Department of Physics, University of New Brunswick, 8 Bailey Drive, Fredericton NB E3B 5A3, Canada. Electronic address: bjb@unb.ca.
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Balcom
keywords: Adiabatic inversion; Porous media; T(2) mapping; T(2) weighting; π Echo Planar Imaging