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Doppler Optical Coherence Tomography of Retinal Circulation

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Published on: September 18, 2012

Maximum likelihood Doppler frequency estimation under decorrelation noise for quantifying flow in optical coherence

Aaron C Chan, Vivek J Srinivasan, Edmund Y Lam

IEEE Transactions on Medical Imaging

|April 25, 2014

Summary

A new maximum likelihood estimator (MLE) improves blood flow measurement accuracy in optical coherence tomography (OCT) by accounting for noise and signal decorrelation, outperforming existing methods.

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Area of Science:

Biomedical Optics
Medical Imaging
Fluid Dynamics

Background:

Optical coherence tomography (OCT) hardware advances enable higher A-scan rates.
Accurate blood flow velocity estimation in OCT is challenged by noise and signal decorrelation.
Existing Doppler velocity estimators, like Kasai's, are suboptimal under common noise conditions.

Purpose of the Study:

To develop a novel maximum likelihood estimator (MLE) for Doppler frequency estimation in OCT.
To address limitations posed by additive white noise and signal decorrelation.
To improve the precision of axial blood flow velocity quantification in OCT.

Main Methods:

Derivation of a general maximum likelihood estimator (MLE) for Doppler frequency.
Inclusion of both additive white noise and signal decorrelation in the estimator model.
Comparison of the decorrelation MLE with existing techniques using simulated and flow phantom data.

Main Results:

The decorrelation MLE demonstrates superior performance compared to existing methods.
The proposed estimator achieves the Cramer-Rao lower bound for Doppler frequency estimation.
An approximation allows for a Fourier domain interpretation of the new estimator.

Conclusions:

The developed decorrelation MLE offers enhanced accuracy for blood flow velocity estimation in OCT.
This estimator is robust to noise and signal decorrelation, common in OCT.
The method is anticipated to be highly valuable for in vivo blood flow measurements using OCT.