Hello everybody,
I have two questions regarding FUGUE.
1. FUGUE tutorials
( http://www.fmrib.ox.ac.uk/fslcourse/lectures/flirt_fugue/s_7063.htm)
says that Unwarping can be done as Fourier phase shift and Pixel shift. I
assume that Pixel shift is a shift of a pixel together with interpolation. I
also assume that it is faster than Fourier phase shift, so why would I want
to use the latter one? Which one is used in FUGUE?
2. FUGUE tutorials
( http://www.fmrib.ox.ac.uk/fslcourse/lectures/flirt_fugue/s_7057.htm )
says that
FIELDMAP = PHASE_DIFF/ASYM_TIME (a)
and
PIXEL_SHIFT = FIELDMAP*N*DWELL/(2PI). (b)
Jezzard et al. 1995 in their MRM paper say at page 66 that
FIELD = PHASE_DIFF/(2PI*GYR_RATIO*ASYM_TIME)
This almost the same as (a), however I am missing gyromagnetic ratio in either
of the equations (a) and (b).
I would appreciate if someone could shed some light into this for me.
Thanks.
Martin
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