Dixon Water Fat Separation
Separate ideal complex in-phase/opposed-phase signals into water=(IP+OP)/2 and fat=(IP−OP)/2; assumes corrected common phase and a single fat peak, not magnitude-only Dixon or B0 solving.
Description
Ideal two-point Dixon separation uses complex in-phase and opposed-phase signals.
Ideal two-point Dixon separation uses complex in-phase and opposed-phase signals. Their sum and difference isolate water and fat under the two-component phase model.
The tool returns waterReal (water real); waterImaginary (water imaginary); fatReal (fat real); fatImaginary (fat imaginary). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Dixon Water Fat Separation
Use Dixon Water Fat Separation when you already have inPhaseReal, inPhaseImaginary, opposedPhaseReal, opposedPhaseImaginary and want waterReal, waterImaginary, fatReal, fatImaginary. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Dixon Water Fat Separation and understand its results
- Enter inPhaseReal, inPhaseImaginary, opposedPhaseReal, opposedPhaseImaginary using the field table below. Match the units, ordering and data boundaries described in the calculation.
- Run the tool after checking the stated bounds and matching paired observations or categories. A malformed request gives a tool error rather than a usable measurement.
- Read waterReal, waterImaginary, fatReal, fatImaginary. Use the calculation and interpretation below to distinguish amounts, ratios, signs and decision flags where applicable.
- Review the supplied parameters and assumptions before using the result in a report or comparing it with another observation.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| inPhaseReal | In phase real | list of number | Required |
| inPhaseImaginary | In phase imaginary | list of number | Required |
| opposedPhaseReal | Opposed phase real | list of number | Required |
| opposedPhaseImaginary | Opposed phase imaginary | list of number | Required |
Use four aligned nonempty real and imaginary lists; apply the same sum/difference to each component. Preserve complex signs.
water = (inPhase+opposedPhase)/2; fat = (inPhase−opposedPhase)/2 The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"inPhaseReal": [
10
],
"inPhaseImaginary": [
2
],
"opposedPhaseReal": [
6
],
"opposedPhaseImaginary": [
0
]
},
"output": {
"waterReal": [
8
],
"waterImaginary": [
1
],
"fatReal": [
2
],
"fatImaginary": [
1
]
}
}Limitations and assumptions
No B0 phase correction, fat-spectrum model, relaxation correction or water-fat ambiguity handling is applied.
Numerical inputs must be finite. The tool checks its declared input shape and calculation constraints; those checks do not verify the quality, calibration or representativeness of the supplied observations.
Alternative or Complementary methods
Nyquist Ghost Correction: Apply supplied linear odd/even phase calibration exp(−i(a+bx)) to an even EPI line; calibration estimation, timing correction and ghost removal efficacy are not inferred. Chemical Shift Artifact Pixels: Estimate signed frequency-encoding chemical-shift displacement using supplied shift, reference frequency and pixel bandwidth; direction depends on readout polarity.
Methodological background: Simple proton spectroscopic imaging.1
References
-
Simple proton spectroscopic imaging — Dixon; Radiology
Similar or alternative tools
- Nyquist Ghost Correction
Apply supplied linear odd/even phase calibration exp(−i(a+bx)) to an even EPI line; calibration estimation, timing correction and ghost removal efficacy are not inferred.
- Chemical Shift Artifact Pixels
Estimate signed frequency-encoding chemical-shift displacement using supplied shift, reference frequency and pixel bandwidth; direction depends on readout polarity.