Input Images for Fat/Water Separation
Fat/Water Separation requires complex data (real/imaginary or magnitude/phase) in order to
work.
Several formats of complex input image data are automatically recognised:
- Separate real and imaginary components in different (real-valued) image slices.
- Separate magnitude and phase components in different (real-valued) image slices.
- Images with a Complex pixel data type (each pixel value is stored as a pair of adjacent
32-bit floating-point values). The program does not work with double-precision (64-bit)
complex images.
If real, imaginary, magnitude and phase images are all present, then the program will only use the
real and imaginary components of the image.
All slices/echo times can be in a single input image. Alternatively, each echo time can be stored
in a separate image. Finally, each complex component and/or echo time can be stored in a separate
image. The program is able to automatically detect these different situations.
For images that have a Complex pixel data type, the images data should structured as follows:
-
If there is a single input image, then all echos for the first slice
location should be followed by all echos for the second slice, followed by all echos for the
third slice, etc.
-
If there are multiple input images, then all echos for the first slice should be in the
first image file. All echos for the second slice should be in the second file, followed by
all echos for the third slice, etc.
You may find the Slice Extractor,
Image Concatenator, and
Image Interleaver useful for helping to organise
your images into the required format.
For images that have complex components in different image slices (real & imaginary, or
magnitude & phase) then the program should be able to determine the organisation of the data
automatically, as long as the images are in DICOM format, or the have been converted
using Jim's Image Converter from a DICOM source.
Note: you can create images with a Complex pixel data type from images that have real &
imaginary or magnitude & phase components in separate images using
the To Complex tool.
When you have set the processing options and the input images,
press the
button to start the processing. Processing will likely take several
minutes to complete due to the complexity of estimating the B0 inhomogeneity.