Phase Field of View
Derive phase-encoding FOV from adjacent gradient-area increments; γ uses cycles/s/T rather than angular units.
Description
Phase-encoding gradient-area increments set adjacent k-space spacing.
Phase-encoding gradient-area increments set adjacent k-space spacing. The reciprocal spacing sets field of view.
The tool returns phaseDeltaKCyclesPerMeter (phase delta k cycles per meter); phaseFovMm (phase fov mm). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Phase Field of View
Use Phase Field of View when you already have gammaHzPerTesla, phaseAreaIncrementMilliTeslaMsPerMeter and want phaseDeltaKCyclesPerMeter, phaseFovMm. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Phase Field of View and understand its results
- Enter gammaHzPerTesla, phaseAreaIncrementMilliTeslaMsPerMeter 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 phaseDeltaKCyclesPerMeter, phaseFovMm. 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 |
|---|---|---|---|
| gammaHzPerTesla | Gamma hz per tesla | number | Required |
| phaseAreaIncrementMilliTeslaMsPerMeter | Phase area increment milli tesla ms per meter | number | Required |
Require positive gamma and gradient-area increment.
deltaK[cycles/m] = gammaHz/T×areaIncrement[mT·ms/m]×10⁻⁶; FOVmm = 1000/deltaK The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"gammaHzPerTesla": 1000000,
"phaseAreaIncrementMilliTeslaMsPerMeter": 4
},
"output": {
"phaseDeltaKCyclesPerMeter": 4,
"phaseFovMm": 250
}
}Limitations and assumptions
The area is an increment between encodings, not the maximum gradient moment. Actual waveforms and hardware limits are external.
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
Phase Matrix Size: Plan the smallest phase matrix meeting a maximum nominal pixel size and caller hardware multiple; this does not estimate true reconstructed spatial resolution. Cartesian K-Space Trajectory: Integrate two-axis piecewise-linear gradients by trapezoids into Cartesian k-space from a zero origin; refocusing sign changes must already be applied to supplied gradients.
Methodological background: RAD229: MRI signal and sequence lecture notes.1
References
-
RAD229: MRI signal and sequence lecture notes — Brian Hargreaves and colleagues, Stanford University
Similar or alternative tools
- Phase Matrix Size
Plan the smallest phase matrix meeting a maximum nominal pixel size and caller hardware multiple; this does not estimate true reconstructed spatial resolution.
- Cartesian K-Space Trajectory
Integrate two-axis piecewise-linear gradients by trapezoids into Cartesian k-space from a zero origin; refocusing sign changes must already be applied to supplied gradients.