MREdisplacement: Calculate the motion induced signal phase for IR-MRE in biphasic material

Description

The function takes magnitude images and phase images (as NIfTI files) recordet with inversion IT1=Inf and a second inversion time IT2 that nulls the fluid signal. Tissue parameters (Relaxation rates) are extracted from an object of class "IRmixed" calculated from data of a related IRMRI experiment.

Usage

MREdisplacement(MagnFiles1, PhaseFiles1, MagnFiles2, PhaseFiles2, TI2 = 2400,
                IRmixobj, method = c("full", "approx"),rescale=FALSE,verbose=FALSE)

Value

A list of class "IRMREbiphasic" with components

phisolid: displacement solid
phifluid: displacement fluid

Arguments

MagnFiles1: Filenames of magnitude images recorded with inversion time IT=Inf .
PhaseFiles1: Filenames of phase images recorded with inversion time IT=Inf .
MagnFiles2: Filenames of magnitude images recorded with inversion time IT=IT2.
PhaseFiles2: Filenames of phase images recorded with inversion time IT=IT2 .
TI2: Inversion time used for MagnFiles2 and PhaseFiles2. IT2 should be selected to extinguish the signal intendity for fluid.
IRmixobj: Object of class "IRmixed" obtained from a related IRMRI experiment.
method: Either "full" or "approx"
rescale: Logical, do we need to rescale phase images ?
verbose: Report scale range of phase images

Author

Karsten Tabelow tabelow@wias-berlin.de
J\"org Polzehl polzehl@wias-berlin.de

Details

The first 4 arguments need to be vectors of filenames of identical length with files containing compatible 3D NIfTI images. Object IRmixobj needs to contain a components segm and Rx of compatible dimension that need to be registered to the MRE images.

References

J. Polzehl and K. Tabelow (2023), Magnetic Resonance Brain Imaging: Modeling and Data Analysis Using R, 2nd Edition, Chapter 7, Springer, Use R! Series. <doi:10.1007/978-3-031-38949-8_7>.