Readout Time
Distinguish N full ADC dwells from the (N−1)-dwell first-to-last timestamp span; gradient ramps are not included.
Description
ADC acquisition duration counts all dwell intervals, while the span between first and last sample centers contains one fewer interval.
ADC acquisition duration counts all dwell intervals, while the span between first and last sample centers contains one fewer interval. The distinction matters at short readouts.
The tool returns acquisitionDurationMs (acquisition duration ms); firstLastSampleSpanMs (first last sample span ms). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Readout Time
Use Readout Time when you already have sampleCount, dwellMicroseconds and want acquisitionDurationMs, firstLastSampleSpanMs. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Readout Time and understand its results
- Enter sampleCount, dwellMicroseconds 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 acquisitionDurationMs, firstLastSampleSpanMs. 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 |
|---|---|---|---|
| sampleCount | Sample count | integer | Required |
| dwellMicroseconds | Dwell microseconds | number | Required |
Require a positive integer sample count and positive dwell time. A single sample has positive duration and zero center-to-center span.
durationMs = sampleCount×dwellMicroseconds/1000; centerSpanMs = (sampleCount−1)×dwellMicroseconds/1000 The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"sampleCount": 256,
"dwellMicroseconds": 10
},
"output": {
"acquisitionDurationMs": 2.56,
"firstLastSampleSpanMs": 2.55
}
}Limitations and assumptions
No receiver dead time, gradient ramps or timing alignment is included.
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
Readout Matrix Size: Fit complete ADC dwell intervals into a supplied readout window and retain the unused tail rather than rounding an infeasible fractional matrix size. Bandwidth Per Pixel: Convert full-span ADC receiver bandwidth to frequency-encoding bandwidth per reconstructed readout sample; vendor half-bandwidth conventions must be converted first.
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
- Readout Matrix Size
Fit complete ADC dwell intervals into a supplied readout window and retain the unused tail rather than rounding an infeasible fractional matrix size.
- Bandwidth Per Pixel
Convert full-span ADC receiver bandwidth to frequency-encoding bandwidth per reconstructed readout sample; vendor half-bandwidth conventions must be converted first.