Double Inversion Black Blood TI
Model ideal fresh-blood single-inversion nulling and resident-tissue recovery after nonselective then selective inversion; flow replacement, TR history and imperfect inversion are excluded.
Description
Double-inversion blood suppression depends on different inversion histories of fresh blood and resident tissue.
Double-inversion blood suppression depends on different inversion histories of fresh blood and resident tissue. Their longitudinal fractions can therefore recover differently.
The tool returns freshBloodLongitudinalFraction (fresh blood longitudinal fraction); residentTissueLongitudinalFraction (resident tissue longitudinal fraction). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Double Inversion Black Blood TI
Use Double Inversion Black Blood TI when you already have bloodT1Ms, bloodNullDelayMs, tissueT1Ms, intervalBetweenInversionsMs and want freshBloodLongitudinalFraction, residentTissueLongitudinalFraction. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Double Inversion Black Blood TI and understand its results
- Enter bloodT1Ms, bloodNullDelayMs, tissueT1Ms, intervalBetweenInversionsMs 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 freshBloodLongitudinalFraction, residentTissueLongitudinalFraction. 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 |
|---|---|---|---|
| bloodT1Ms | Blood t1 ms | number | Required |
| bloodNullDelayMs | Blood null delay ms | number | Required |
| tissueT1Ms | Tissue t1 ms | number | Required |
| intervalBetweenInversionsMs | Interval between inversions ms | number | Required |
Use positive T1 values and nonnegative delay and inversion interval in ms. Evaluate the two ideal histories separately.
blood = 1−2exp(−delay/T1blood); tissue = 1−2(1−exp(−inversionInterval/T1tissue))exp(−delay/T1tissue) The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"bloodT1Ms": 1000,
"bloodNullDelayMs": 693.1471805599452,
"tissueT1Ms": 1000,
"intervalBetweenInversionsMs": 100
},
"output": {
"freshBloodLongitudinalFraction": 0,
"residentTissueLongitudinalFraction": 0.9048374180359595
}
}Limitations and assumptions
Perfect inversions and the prescribed fresh/resident compartments are assumed. Flow, incomplete replacement and readout saturation are not simulated.
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
Inversion Time TI: Solve an ideal repeated inversion-recovery null TI=T1·ln[2/(1+exp(−TR/T1))]; assumes ideal inversion and saturation/readout convention, not a patient-specific protocol. Spin Echo Signal Intensity: Evaluate an ideal saturation-recovery spin-echo signal M0(1−e^(−TR/T1))e^(−TE/T2); refocusing imperfections and stimulated echoes are excluded.
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
- Inversion Time TI
Solve an ideal repeated inversion-recovery null TI=T1·ln[2/(1+exp(−TR/T1))]; assumes ideal inversion and saturation/readout convention, not a patient-specific protocol.
- Spin Echo Signal Intensity
Evaluate an ideal saturation-recovery spin-echo signal M0(1−e^(−TR/T1))e^(−TE/T2); refocusing imperfections and stimulated echoes are excluded.