Annualized Brain Atrophy Calculator

Explicit linear annualized baseline-relative brain-volume loss, not compound geometric shrinkage, SIENA/BBSIimage processing or dementia diagnosis. Negative loss retains measured growth; protocol and scan uncertainty independently reviewed.

Description

Annualized brain atrophy expresses baseline-relative volume loss over elapsed years.

Annualized brain atrophy expresses baseline-relative volume loss over elapsed years.^[1]

Linear annualization differs from compound annual change.

When to use Annualized Brain Atrophy 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 Annualized Brain Atrophy Calculator and understand its results

Establish the assessment or recording protocol, units, instrument version and independently applicable reference or calibration.
Enter independentlyMeasuredBaselineBrainVolumeMl, independentlyMeasuredFollowupBrainVolumeMl, independentlyMeasuredElapsedYears, using the field meanings and rules below, then run the tool.
Read result.signedBaselineRelativeLossPercentPerYear. 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
independentlyMeasuredBaselineBrainVolumeMl	Independently measured baseline brain volume ml	number	Required
independentlyMeasuredFollowupBrainVolumeMl	Independently measured followup brain volume ml	number	Required
independentlyMeasuredElapsedYears	Independently measured elapsed years	number	Required

Require positive baseline volume, nonnegative follow-up volume and positive elapsed years. Return 100×(1−followup/baseline)/years; follow-up above baseline gives a negative loss rate. No compound annualization is applied.

lossPercentPerYear=100×(1−followupMl/baselineMl)/elapsedYears

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.signedBaselineRelativeLossPercentPerYear	Signed Baseline Relative Loss Percent Per Year; preserve the subtraction order and sign defined in the mechanics	number

json

{
  "input": {
    "independentlyMeasuredBaselineBrainVolumeMl": 1000,
    "independentlyMeasuredFollowupBrainVolumeMl": 900,
    "independentlyMeasuredElapsedYears": 2
  },
  "output": {
    "result": {
      "signedBaselineRelativeLossPercentPerYear": 4.999999999999999
    }
  }
}

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 Pruning Rate Calculator: A synapse-count reduction rate compares matched earlier and later observations. For a complementary comparison, use Brain Growth Rate Calculator: Brain-volume growth rate compares matched volumes over an established elapsed time.

References

Annualized Brain Atrophy Calculator — tool.io

Similar or alternative tools

Pruning Rate Calculator
A synapse-count reduction rate compares matched earlier and later observations.
Brain Growth Rate Calculator
Brain-volume growth rate compares matched volumes over an established elapsed time.