MRI Sequence Parameter Calculator
Calculate MRI scan time and resolution from sequence parameters.
About MRI Sequence Parameter Calculator
Scan time is linear in phase encoding steps and averages, while signal to noise improves only as the square root of averages. Doubling averages therefore doubles scan time for a 41 per cent signal gain. Resolution, signal and scan time cannot all be improved at once, and this relationship is the trade-off every protocol decision comes back to.
Formula
MRI Sequence Parameter
Scan time = TR × phase encoding steps × averages
- TR
- Repetition time between excitations
- averages
- Repeat acquisitions, improving signal as the square root of the count
Worked example
With the default values below, MRI Sequence Parameter Calculator returns Scan Time of 21.333. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Repetition timeminimum 1 ms
- 2,500 ms
- Phase encoding stepsminimum 1
- 256
- Number of slicesminimum 1
- 30
- Signal averagesminimum 1
- 2
- Field of viewminimum 1 mm
- 240 mm
Results
- Scan Time
- 21.333 min
- Scan Time
- 1,280.0 s
- In-Plane Resolution
- 0.9375 mm
- Relative Signal to Noise
- 1.326 x
- Time per Slice
- 42.667 s
Step by step
- 1Values used
- 2MRI Sequence Parameter
- 3Scan Time= 21.333 min
- 4Scan Time= 1,280.0 s
- 5In-Plane Resolution= 0.9375 mm
- 6Relative Signal to Noise= 1.326 x
- 7Time per Slice= 42.667 s
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- This is an educational tool for understanding MRI sequence relationships. It is not for clinical protocol design or patient scanning decisions, which must be made by qualified radiographers and medical physicists.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
This is an educational tool for understanding MRI sequence relationships. It is not for clinical protocol design or patient scanning decisions, which must be made by qualified radiographers and medical physicists.
Frequently Asked Questions
How is MRI Sequence Parameter calculated?
Scan time = TR × phase encoding steps × averages Scan time is linear in phase encoding steps and averages, while signal to noise improves only as the square root of averages. Doubling averages therefore doubles scan time for a 41 per cent signal gain.
Why does MRI Sequence Parameter matter?
Resolution, signal and scan time cannot all be improved at once, and this relationship is the trade-off every protocol decision comes back to.
What values do I need to enter?
This calculator takes 5 inputs: Repetition time, Phase encoding steps, Number of slices, Signal averages, Field of view. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.