Calculate MRI scan time and resolution from sequence parameters.
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.
MRI Sequence Parameter
Scan time = TR × phase encoding steps × averages
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.
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.
Resolution, signal and scan time cannot all be improved at once, and this relationship is the trade-off every protocol decision comes back to.
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.