Shear wave elastography using amplitude-modulated acoustic radiation force and phase-sensitive optical coherence...

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Acoustics

Background:

• Ocular tissue elasticity is vital for understanding and managing biomechanical deficiencies.
• Previous optical coherence tomography-based shear wave elastography (SWE) offered high resolution and sensitivity.
• Acoustic radiation force is used to induce shear waves for elastography, but minimizing ultrasound pressure is critical for ocular safety.

Purpose of the Study:

• To develop and validate a pulse compression ultrasound approach for shear wave elastography (SWE) in ocular tissues.
• To reduce the maximum acoustic pressure used for inducing shear waves, enhancing safety in ophthalmic applications.
• To demonstrate the feasibility of low-pressure SWE measurements in tissue-mimicking phantoms.

Main Methods:

• A pulse compression technique was employed, utilizing coded ultrasound (US) emissions.
• Coded excitations modulated by a linear frequency-swept square wave (1-7 kHz) were used with a 7.5-MHz focused transducer.
• An inverse filter approach was applied for numerical compression of the US signal to generate localized, high-energy pulses.

Main Results:

• The pulse compression method successfully generated shear waves using coded ultrasound emissions.
• Shear wave elastography measurements were feasible in tissue-mimicking phantoms.
• The technique achieved measurements at significantly low ultrasound pressures (mechanical index < 0.6).

Conclusions:

• The proposed pulse compression approach is a feasible method for safe, low-pressure shear wave elastography in ocular tissues.
• This technique holds promise for improving the understanding and management of ocular pathologies related to biomechanical properties.
• Further research can explore its application in in-vivo ophthalmic diagnostics.