Phase unwrapping for MHz optical coherence elastography and application to brain tumor tissue

Area of Science:

• Biomedical Optics
• Medical Imaging
• Surgical Technology

Background:

• Phase-sensitive optical coherence elastography (OCE) is crucial for differentiating healthy from diseased tissue during neuro-oncologic surgery.
• The phase unwrapping process is a critical bottleneck in retrieving accurate phase signals for OCE analysis.

Purpose of the Study:

• To develop and validate a novel one-dimensional (1D) unwrapping algorithm for phase-sensitive OCE.
• To improve the accuracy and reliability of tissue deformation measurements in neuro-oncologic applications.

Main Methods:

• Implementation of a 1D phase unwrapping algorithm tailored for a 3.2 MHz OCE system.
• Utilized Graphics Processing Unit (GPU) for accelerated processing, achieving approximately 0.11 s per frame.
• Algorithm detects and corrects multiple 2π phase wraps to recover the original phase signal.

Main Results:

• The algorithm successfully recovers phase signals with pixel accuracy, enabling exact and reproducible tissue deformation measurements.
• Demonstrated high reliability in distinguishing between healthy and diseased tissues using brain tumor-mimicking phantoms.
• Validated findings through correlation with histological data on human ex vivo brain tumor samples subjected to air pulse stimulation.

Conclusions:

• The developed 1D unwrapping algorithm significantly enhances the utility of phase-sensitive OCE in neuro-oncologic surgery.
• Provides a robust and efficient method for obtaining precise tissue deformation information, aiding in surgical decision-making.
• Confirms the algorithm's dependability and potential for real-time clinical application in distinguishing tumor margins.