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.
Description
Phase matrix planning chooses enough pixels to meet a maximum spatial size while respecting a required matrix multiple.
Phase matrix planning chooses enough pixels to meet a maximum spatial size while respecting a required matrix multiple. Rounding upward protects the resolution bound.
The tool returns phaseMatrixSize (phase matrix size); actualPixelMm (actual pixel 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 Matrix Size
Use Phase Matrix Size when you already have phaseFovMm, maximumPixelMm, requiredMatrixMultiple and want phaseMatrixSize, actualPixelMm. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Phase Matrix Size and understand its results
- Enter phaseFovMm, maximumPixelMm, requiredMatrixMultiple 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 phaseMatrixSize, actualPixelMm. 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 |
|---|---|---|---|
| phaseFovMm | Phase fov mm | number | Required |
| maximumPixelMm | Maximum pixel mm | number | Required |
| requiredMatrixMultiple | Required matrix multiple | integer | Required |
Use positive FOV and maximum pixel size and a positive integer multiple.
matrix = ceil(FOVmm/maximumPixelMm/multiple)×multiple; pixelMm = FOVmm/matrix The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"phaseFovMm": 240,
"maximumPixelMm": 1.1,
"requiredMatrixMultiple": 8
},
"output": {
"phaseMatrixSize": 224,
"actualPixelMm": 1.0714285714285714
}
}Limitations and assumptions
This is a geometric plan, without scan-time, SNR, scanner matrix limits or image-resolution validation.
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 Field of View: Derive phase-encoding FOV from adjacent gradient-area increments; γ uses cycles/s/T rather than angular units. Echo Train Length: Allocate required phase lines into bounded echo trains, retaining a short final shot; echo weighting, k-space ordering and sequence-specific ETL definitions are external.
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 Field of View
Derive phase-encoding FOV from adjacent gradient-area increments; γ uses cycles/s/T rather than angular units.
- Echo Train Length
Allocate required phase lines into bounded echo trains, retaining a short final shot; echo weighting, k-space ordering and sequence-specific ETL definitions are external.