Doppler-Flow Perfusion Index
Calculate a first-moment laser-Doppler perfusion index from a supplied spectrum.
Description
A laser-Doppler spectral first moment weights power by absolute frequency.
A laser-Doppler spectral first moment weights power by absolute frequency. Normalizing by total power yields a mean absolute frequency.1
Calculate a first-moment laser-Doppler perfusion index from a supplied spectrum.
When to use Doppler-Flow Perfusion Index
Use this tool to calculate a first-moment laser-Doppler perfusion index from a supplied spectrum.
Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
How to use Doppler-Flow Perfusion Index and understand its results
- Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
- Enter dopplerFrequenciesHertz, powerSpectrum using the field table and calculation rules, then run the tool.
- Read totalDopplerPower, meanAbsoluteFrequencyHertz, perfusionIndex. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| dopplerFrequenciesHertz | Doppler frequency bins (Hz) | list of number | Required |
| powerSpectrum | Doppler power spectrum | list of number | Required |
Enter nonempty aligned finite frequencies and nonnegative spectral values with positive total. Return total power, mean absolute Hz and unnormalized index.
index=Σ|f_i|P_i; meanAbsFrequency=index/ΣP_i Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| totalDopplerPower | Total Doppler power | number; minimum: 0 |
| meanAbsoluteFrequencyHertz | Power-weighted mean absolute frequency (Hz) | number; minimum: 0 |
| perfusionIndex | First-moment perfusion index (Hz·power) | number; minimum: 0 |
{
"input": {
"dopplerFrequenciesHertz": [
-2,
0,
2
],
"powerSpectrum": [
1,
2,
1
]
},
"output": {
"totalDopplerPower": 4,
"meanAbsoluteFrequencyHertz": 1,
"perfusionIndex": 4
}
}Limitations and assumptions
No bin-width integration, spectral calibration, artifact removal or clinical perfusion scale is supplied.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Speckle Contrast: Calculate population speckle contrast from an intensity region. For a complementary task, use Speckle Decorrelation: Calculate frame-to-frame speckle correlation and decorrelation.
References
-
Doppler-Flow Perfusion Index — tool.io
Similar or alternative tools
- Speckle Contrast
Calculate population speckle contrast from an intensity region.
- Speckle Decorrelation
Calculate frame-to-frame speckle correlation and decorrelation.