MREdisplacement function

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

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.

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

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

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.

Returns

A list of class "IRMREbiphasic" with components - phisolid: displacement solid

• phifluid: displacement fluid

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.

Author(s)

Karsten Tabelow tabelow@wias-berlin.de

J"org Polzehl polzehl@wias-berlin.de

See Also

estimateIRfluid, estimateIRsolid, estimateIRsolidfixed,smoothIRSolid