Full-waveform ultrasound modeling of soft tissue-bone interactions using conforming hexahedral meshes

Marty, Patrick; Boehm, Christian; Paverd, Catherine; Rominger, Marga B.; Fichtner, Andreas

doi:10.1117/12.2611548

Cited by 3 publications

(4 citation statements)

References 26 publications

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“…16,17,20 In addition to its use within seismological applications, the SEM has been shown to be an effective tool within medical ultrasound simulations. 9,21,22 The SEM is a specialized higher-order finite-element method which provides a number of attractive numerical properties to offer significant computational benefits over conventional finite-element approaches for solving the wave equation. The primary advantage of the SEM over other finite-element methods is that the mass matrix is diagonal by construction.…”

Section: Spectral-element Methodsmentioning

confidence: 99%

“…25 While strategies exist in both 2D 26 and 3D 27 for constructing such meshes semi-automatically, applying these strategies to highly irregular geometries remains a challenge. 22 The discrete formulations of equations ( 1) and ( 3) are not provided here in the interest of brevity. However, the reader is referred to works such as Komatitsch et al 16 and Afanasiev et al 17 for a comprehensive description of the discrete representation of these coupled wave equations.…”

Section: Spectral-element Methodsmentioning

confidence: 99%

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Towards elastic bone characterization in transcranial ultrasound

Marty,

Mitcham,

Ali

et al. 2024

Medical Imaging 2024: Ultrasonic Imaging and Tomography

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Constructing a physics-augmented digital twin of the skull is imperative for a wide range of transcranial ultrasound applications including ultrasound computed tomography and focused ultrasound therapy. The high impedance contrast as well as the acoustic-elastic coupling observed between soft tissue and bone increase the complexity of the ultrasound wavefield considerably, thus emphasizing the need for waveform-based inversion approaches. This work applies reverse time migration in conjunction with the spectral-element method to an in vitro human skull to obtain a starting model, which can be used for full-waveform inversion and adjoint-based shape optimization. Two distinct brain phantoms are considered where the cranial cavity of the in vitro human skull was filled with (1) homogeneous water and (2) gelatin with two cylindrical inclusions. A 2D slice through the posterior of the skull was collected using a ring-like aperture consisting of 1024 ultrasound transducers with a bandwidth of approximately 1 MHz to 3 MHz. Waveform-based reverse time migration was then used to resolve the inner and outer contours of the skull from which a conforming hexahedral finite-element mesh was constructed. The synthetically generated measurements which are obtained by solving the coupled acousticviscoelastic wave equation are in good agreement with the observed laboratory measurements. It is demonstrated that using this revised wave speed model for recomputing the reverse time migration reconstructions allows for improved localization of the gelatin inclusions within the cranial cavity.

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Section: Spectral-element Methodsmentioning

confidence: 99%

Section: Spectral-element Methodsmentioning

confidence: 99%

Towards elastic bone characterization in transcranial ultrasound

Marty,

Mitcham,

Ali

et al. 2024

Medical Imaging 2024: Ultrasonic Imaging and Tomography

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“…Notwithstanding, a hexahedron element is more appropriate in the case of a simple structure. 18) Therefore, the 3D structure was created as a hexahedron and the 2D structure as a quadrilateral element to maximize computational efficiency. To ensure the accuracy of the model, it was necessary to check whether the analysis results were within the range of convergence or not.…”

Section: Optimizationmentioning

confidence: 99%

Overlay and CD uniformity variation due to wafer thermal deformation caused by EUV exposure

Ko¹,

Choi²,

Kim³

et al. 2023

Jpn. J. Appl. Phys.

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Extreme ultraviolet lithography (EUVL) process allows for the manufacturing of better- performance chips. However, the EUV exposure process might contribute to significant variations in the patterns of circuits, which cause serious image placement and flatness change. And, during the exposure, the EUV absorption might cause local wafer thermal deformation that might cause the overlay and local critical dimension (CD) variation. In this study, we investigated the wafer thermal deformation with different CDs and pitches with EUV exposure and the thermo-mechanical behavior of the photoresist using the finite element method (FEM) simulation. It is found that the thermal deformation caused during EUV exposure is different inside a die. In the direction along the scan, thermal deformation is increased as it is nearer to the center of the slit. The deformation in the perpendicular direction is increased as it approaches the edges and deforms in the opposite direction relative to the center of the slit. In both directions, the thermal deformation increases gradually as the scan progresses, and it could be as large as ~ 1.5 nm in a die. There was no difference in thermal deformation by CD change, but it is changed with pitch.

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“…Parenthetically, some recent academic works on the human brain have focused on the use of the acoustic fullwaveform inversion to build a high-accuracy velocity map, requiring an ad hoc ultrasound scan, significant HPC resources, and non-negligible quality control [23,24]; although innovative and aimed at competing with MRI, its industrial implementation would be extremely costly in all aspects if compared with forthcoming ultrasound systems equipped with high-performance hardware to process in real time, or quasi-real time, more accurate imaging models than the standard one.…”

mentioning

confidence: 99%

Seismic imaging of medical ultrasound data: Towards in vivo applications

Theis¹,

Bonomi²

2023

EPL

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This study presents the application to medical ultrasonography of a high value-added imaging method developed in the context of geophysical exploration and based on the undulatory description of the physical process. Currently, the most serious limitation of conventional medical ultrasound systems is the implicit assumption of constant-velocity media stemming from the widespread use of geometrical ray-based imaging algorithms and leading to phase aberration phenomena in the case typical of the human body of two or more tissues with different velocities. As a result, imaging of targets underlying tissue layers can be severely degraded. To address this problem, the proposed algorithm is designed expressly for variable-velocity media, providing high-resolution images by implementing the solution of the one-way wave equation. From a macro-velocity model, the illuminated structures are imaged by correlating, in the frequency domain and for each source element, the simulated emitted wavefield with the back-propagated echoes sensed by the ultrasound transducer. The pointwise sum of the correlations reveals, constructively, all diffraction points and reflectors in the image space. The experiments conducted on in vitro laboratory data reveal remarkable spatial resolution and very accurate target positioning, even in the presence of an aberrant layer. A preliminary in vivo test also demonstrates the method's effectiveness in imaging echoes recorded on human tissues, giving a glimpse of its potentiality for clinical purposes.

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Full-waveform ultrasound modeling of soft tissue-bone interactions using conforming hexahedral meshes

Cited by 3 publications

References 26 publications

Towards elastic bone characterization in transcranial ultrasound

Towards elastic bone characterization in transcranial ultrasound

Overlay and CD uniformity variation due to wafer thermal deformation caused by EUV exposure

Seismic imaging of medical ultrasound data: Towards in vivo applications

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