CSF Plasma Ratio Calculator

Actual same basis CSF/plasma exposure partition, not brain homogenate partition; actual compatible definitions and matching units required, no causal efficacy/diagnosis or safety claim.

Description

A CSF-to-plasma ratio requires concentration measurements on the same analytical basis and matched context.

A CSF-to-plasma ratio requires concentration measurements on the same analytical basis and matched context.^[1]

This tool calculates their ratio without correcting free fractions or substituting brain homogenate measurements.

When to use CSF Plasma Ratio Calculator

This tool calculates their ratio without correcting free fractions or substituting brain homogenate measurements.

How to use CSF Plasma Ratio Calculator and how it works

Prepare matched csf concentration, matched plasma concentration, using the input definitions and matching units below.
Enter the required fields and run CSF Plasma Ratio Calculator.
Read result.value using the units, signs and ordering explained below.
Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.

Input field	Meaning	Value type	Requirement
actualMatchedCsfConcentration	Actual Matched Csf Concentration. Use the units and matching context stated in the calculation below.	number	Required; nonnegative; finite; other constraints below
actualMatchedPlasmaConcentration	Actual Matched Plasma Concentration. Use the units and matching context stated in the calculation below.	number	Required; strictly positive; finite; other constraints below

Require nonnegative matched CSF concentration and positive plasma concentration on the same basis. Return their ratio without an upper cap or binding correction. Sampling context and analytical comparability are independently established.

csfPlasmaRatio=csfConcentration/plasmaConcentration

Apply the input ordering, units and branch conditions stated above.

Output field	Meaning	Value type
result	Object containing the calculated or selected fields below.	object
result.value	Numeric model result on the ratio, score, constant or density basis explained above.	number

json

{
  "input": {
    "actualMatchedCsfConcentration": 2,
    "actualMatchedPlasmaConcentration": 4
  },
  "output": {
    "result": {
      "value": 0.5
    }
  }
}

Limitations and assumptions

The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.

All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.

Alternative or Complementary methods

Use Tau PET SUVR Calculator for a complementary operation: PET standardized uptake value ratio compares a target-region mean with a matched reference-region mean.

Use FDG PET SUVR Calculator for a complementary operation: An FDG PET uptake ratio depends on matched tracer timing and a separately chosen reference region.

References

CSF Plasma Ratio Calculator — tool.io

Similar or alternative tools

Tau PET SUVR Calculator
PET standardized uptake value ratio compares a target-region mean with a matched reference-region mean.
FDG PET SUVR Calculator
An FDG PET uptake ratio depends on matched tracer timing and a separately chosen reference region.