3-D Wave-Equation-Based Finite-Frequency Tomography for Ultrasound Computed Tomography

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Acoustics

Background:

• Ultrasound computed tomography (USCT) shows promise for 3-D quantitative imaging of breast tissue properties.
• High-frequency transducers in USCT pose computational challenges for traditional wave propagation simulations.
• Current methods often rely on ray-theoretical approaches despite the finite-frequency nature of ultrasound.

Purpose of the Study:

• To introduce a finite-frequency traveltime tomography method for medical ultrasound applications.
• To address computational challenges in 3-D USCT imaging at high frequencies.
• To improve the accuracy and capabilities of quantitative breast tissue imaging.

Main Methods:

• Developed a finite-frequency traveltime tomography approach for medical ultrasound.
• Utilized calibration data in water to linearize the forward problem and derive analytical sensitivity expressions.
• Implemented a memory-efficient Jacobian operator using 1-D parameterization for computational efficiency.

Main Results:

• The method accurately accounts for frequency dependence and volumetric sensitivity, including off-ray-path scattering and diffraction.
• Demonstrated the capability for out-of-plane imaging and 3-D reconstruction from 2-D slice-by-slice data.
• Validated the tomographic approach with laboratory measurements and phantom data, showing applicability for 3-D reconstructions.

Conclusions:

• Finite-frequency traveltime tomography offers a computationally tractable and accurate solution for 3-D USCT breast imaging.
• The method enhances quantitative imaging by incorporating wave phenomena like scattering and diffraction.
• This approach facilitates 3-D imaging and enables slice-by-slice acquisition strategies for improved breast tissue characterization.