CBF Quantification ASL

Evaluate the ideal single-compartment pCASL CBF equation with supplied calibration and timing; negative measured ΔM is preserved, and transit delay, exchange and partial-volume effects are not corrected.

Description

Single-compartment pCASL flow quantification relates label-control signal difference to equilibrium signal and label decay.

Single-compartment pCASL flow quantification relates label-control signal difference to equilibrium signal and label decay. Label duration and post-label delay contribute differently.

The tool returns cbfMlPer100GramMinute (cbf ml per100 gram minute). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.

When to use CBF Quantification ASL

Use CBF Quantification ASL when you already have deltaM, referenceM0, partitionMlPerGram, labelEfficiency, bloodT1Seconds, labelDurationSeconds, postLabelDelaySeconds and want cbfMlPer100GramMinute. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.

How to use CBF Quantification ASL and understand its results

Enter deltaM, referenceM0, partitionMlPerGram, labelEfficiency, bloodT1Seconds, labelDurationSeconds, postLabelDelaySeconds 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 cbfMlPer100GramMinute. 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
deltaM	Delta m	number	Required
referenceM0	Reference m0	number	Required
partitionMlPerGram	Partition ml per gram	number	Required
labelEfficiency	Label efficiency	number	Required
bloodT1Seconds	Blood t1 seconds	number	Required
labelDurationSeconds	Label duration seconds	number	Required
postLabelDelaySeconds	Post label delay seconds	number	Required

Use times in seconds, partition in mL/g, positive M0 and T1, efficiency in (0,1], positive label duration and nonnegative PLD. Return mL/100 g/min.

CBF = 6000×partition×deltaM×exp(PLD/T1blood) / [2×efficiency×T1blood×M0×(1−exp(−labelDuration/T1blood))]

The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.

json

{
  "input": {
    "deltaM": 1,
    "referenceM0": 100,
    "partitionMlPerGram": 0.9,
    "labelEfficiency": 0.8,
    "bloodT1Seconds": 1.5,
    "labelDurationSeconds": 1.8,
    "postLabelDelaySeconds": 1
  },
  "output": {
    "cbfMlPer100GramMinute": 62.71272601168574
  }
}

Limitations and assumptions

Signed deltaM can produce negative flow. Transit-time assumptions, labeling calibration, background suppression and motion are not verified.

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

BOLD Percent Signal Change: Compute BOLD percent signal change from explicit disjoint sampled baseline/task windows; motion, drift and hemodynamic modeling are not performed. 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: Recommended Implementation of Arterial Spin Labeled Perfusion MRI for Clinical Applications.^[1]

References

Recommended Implementation of Arterial Spin Labeled Perfusion MRI for Clinical Applications — Alsop et al.; ISMRM and European Consortium for ASL in Dementia

Similar or alternative tools

BOLD Percent Signal Change
Compute BOLD percent signal change from explicit disjoint sampled baseline/task windows; motion, drift and hemodynamic modeling are not performed.
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.