Gray Matter Fraction Calculator
Actual same-mask segment/ICVfraction with qualified segmentation, not age norm or disease determination. Independently measured compatible definitions/units required; ratio is not a diagnosis, efficacy measure or safety/clinical threshold.
Description
Gray-matter fraction compares a segmented gray-matter volume with matched intracranial volume.
Gray-matter fraction compares a segmented gray-matter volume with matched intracranial volume.1
It differs from the share of gray matter in parenchyma alone.
When to use Gray Matter Fraction Calculator
Use this tool to calculate or review the supplied observations under the stated rules. Establish the assessment or recording protocol, units, instrument version and independently applicable reference or calibration.
How to use Gray Matter Fraction Calculator and understand its results
- Establish the assessment or recording protocol, units, instrument version and independently applicable reference or calibration.
- Enter independentlySegmentedGrayMatterMl, independentlyMatchedIntracranialMl, using the field meanings and rules below, then run the tool.
- Read result.observedRatio. Use the units and sign conventions below.
- Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| independentlySegmentedGrayMatterMl | Independently segmented gray matter ml | number | Required |
| independentlyMatchedIntracranialMl | Independently matched intracranial ml | number | Required |
Supply a nonnegative independentlySegmentedGrayMatterMl and strictly positive independentlyMatchedIntracranialMl. Divide the first by the second for a dimensionless ratio. The general ratio calculation does not clamp the result or require the numerator to be no greater than the denominator; a larger numerator can return above one. Establish matching observation scope and units independently.
observedRatio=1×independentlySegmentedGrayMatterMl/independentlyMatchedIntracranialMl Use the matching field units and the exact boundary, ordering and reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Structured result; its nested fields below contain the actual calculation or selected reference | object |
| result.observedRatio | Observed Ratio; dimensionless ratio, without percent scaling | number |
{
"input": {
"independentlySegmentedGrayMatterMl": 2,
"independentlyMatchedIntracranialMl": 4
},
"output": {
"result": {
"observedRatio": 0.5
}
}
}Limitations and assumptions
Actual acquisition, assessment protocol, instrument version and calibration determine applicability. The tool does not examine a person, classify images, administer a questionnaire or choose diagnostic cutoffs.
Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.
Alternative or Complementary methods
For a related step, use White Matter Fraction Calculator: White-matter fraction expresses a segmented volume relative to a matched intracranial volume. For a complementary comparison, use CSF Fraction Calculator: CSF fraction relates segmented cerebrospinal-fluid volume to matched intracranial volume.
References
-
Gray Matter Fraction Calculator — tool.io
Similar or alternative tools
- White Matter Fraction Calculator
White-matter fraction expresses a segmented volume relative to a matched intracranial volume.
- CSF Fraction Calculator
CSF fraction relates segmented cerebrospinal-fluid volume to matched intracranial volume.