Blocked Elements in 1-D and 2-D Arrays—Part I: Detection and Basic Compensation on Simulated and <i>In Vivo</i> Targets

Jakovljevic, Marko; Pinton, Gianmarco; Dahl, Jeremy J.; Trahey, Gregg E.

doi:10.1109/tuffc.2017.2683559

Cited by 11 publications

(6 citation statements)

References 19 publications

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“…Although the 3-D models and simulations incorporate the elevation dimension, a consistent decrease in image degradation was not observed compared to the 2-D simulations, as might be expected due to the 2-D nature of phase aberration and reverberation clutter. 11,[32][33][34] The 3-D simulations show clutter and phase aberration in both greater and lesser extents to their 2-D simulation counterparts, meaning that the 2-D simulations are not a simple prediction of the 3-D tissue structure.…”

Section: Discussionmentioning

confidence: 96%

“…The 3-D acoustic models of complex human tissue previously have been generated from MRI volumes of excised human breast tissue 10 and from MRI and x-ray CT images made available through the National Library of Medicine's The Visible Human Project. [11][12][13] However, these models do not represent tissue layout in its natural state. The processes of excising and/or fixing tissue used in histological staining and in The Visible Human Project result in tissue shrinkage and deformations that are not seen in vivo.…”

Section: Introductionmentioning

confidence: 99%

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Unsupervised clustering method to convert high-resolution magnetic resonance volumes to three-dimensional acoustic models for full-wave ultrasound simulations

et al. 2019

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Simulations of acoustic wave propagation, including both the forward and the backward propagations of the wave (also known as full-wave simulations), are increasingly utilized in ultrasound imaging due to their ability to more accurately model important acoustic phenomena. Realistic anatomic models, particularly those of the abdominal wall, are needed to take full advantage of the capabilities of these simulation tools. We describe a method for converting fat-water-separated magnetic resonance imaging (MRI) volumes to anatomical models for ultrasound simulations. These acoustic models are used to map acoustic imaging parameters, such as speed of sound and density, to grid points in an ultrasound simulation. The tissues of these models are segmented from the MRI volumes into five primary classes of tissue in the human abdominal wall (skin, fat, muscle, connective tissue, and nontissue). This segmentation is achieved using an unsupervised machine learning algorithm, fuzzy c-means clustering (FCM), on a multiscale feature representation of the MRI volumes. We describe an automated method for utilizing FCM weights to produce a model that achieves ∼90% agreement with manual segmentation. Two-dimensional (2-D) and three-dimensional (3-D) full-wave nonlinear ultrasound simulations are conducted, demonstrating the utility of realistic 3-D abdominal wall models over previously available 2-D abdominal wall models.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Unsupervised clustering method to convert high-resolution magnetic resonance volumes to three-dimensional acoustic models for full-wave ultrasound simulations

et al. 2019

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“…This method was shown to improve the image quality of point target phantoms. Jakovljevic et al [12], used the Fullwave simulation tool and a clinical ultrasound scanner to characterize the signals from a fully sampled matrix array. It was shown that blocked elements had a lower amplitude and lower nearest-neighbor correlation.…”

Section: Introductionmentioning

confidence: 99%

Ultrasound imaging with three dimensional full-wave nonlinear acoustic simulations. Part 2: sources of image degradation in intercostal imaging

Pinton¹

2020

Preprint

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Full-wave simulations are applied to an intercostal imaging scenario to determine the sources of fundamental and harmonic image degradation with respect to aberration and reverberation. These simulations are based on Part I of this two part paper, which established the full-wave simulation methods to generate realistic ultrasound images based directly on the first principles of wave propagation in the human body. The ultasound images are generated based on the first principles of propagation and reflection. By relying on first priniples of the three dimensional wave propagation physics the interplay between distributed aberration and reverberation clutter can be fully appreciated. Three imaging scenarios that would not be realizable in vivo are investigated in silico. First, the ribs were completely removed and replaced with fat. Then, the ribs were maintained in their anatomically correct configuration to yield a reference image. Finally the ribs were placed closer together in elevation. The propagation based B-mode images show that of these three scenarios the second, anatomically correct configuration, has the best contrast-to-noise ratio. This is due to two competing effects. First it is shown that the ribs effectively apodize the fundamental and harmonic beams by 3-5 dB. This effect alone would predict an improvement in image quality. However, the B-mode image quality, measured by the contrast-to-noise ratio degrades by 8%. To fully explain these changes, it is shown that a second effect, multiple reverberation, must be taken into account. A point spread function analysis shows that when the ribs are placed closer together they also generate significantly more reverberation clutter (by 2.4 to 2.9 dB), which degrades the image quality even though the beamplot has lower sidelobes. In this intercostal imaging scenario the effects of the ribs on beam shape and reverberation are therefore in competition in terms of image quality and there is an optimal acoustic window that balances them out. This simulation tool and image quality analysis could be applied to other imaging configurations and in other areas of the body.

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“…This simulation tool has been previously used to generate ultrasound images, to study the sources of image degradation [10], [11] and to understand the principles behind new imaging methods, such as short lag spatial coherence imaging [12]. It has also been used to simulate how elements that are blocked by ribs can degrade the image quallity [13]. Although the capability to simulate in three dimensions with Fullwave has existed since its inception and although it has been used extensively in three dimensional therapuetic applications [14], [11], it's use for imaging in three dimensional domains has not been previously described.…”

Section: Introductionmentioning

confidence: 99%

Ultrasound imaging of the human body with three dimensional full-wave nonlinear acoustics. Part 1: simulations methods

Pinton

2020

Preprint

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Simulations of three dimensional ultrasound propagation in heterogeneous media are computationally intensive due to the combined constraints arising from the large size of the domain, which is on the order of hundreds of wavelengths, and the small size of scatterers, which can be much smaller than a wavelength. For this reason three dimensional ultrasound imaging simulations are currently based on models that simplify the propagation physics. Here the full three dimensional wave physics is simulated with finite differences to generate ultrasound images of the human body based directly on the first principles of propagation and backscattering. The Visible Human project, a 3D data set of the human body that was generated with photographs of 0.33 mm cryosections, is converted into 3D acoustical maps. A full-wave nonlinear acoustic simulation tool is used to propagate ultrasound into the liver with a 2D transcostal ultrasound array in a 93 × 39 × 22 mm domain with 6 × 10 8 points. Imaging metrics, based on the beamplots, root-mean-square phase aberration, spatial coherence lengths, and contrast-to-noise ratio are used to characterize the image quality. It is shown that the harmonic image quality is better than the fundamental image quality due, in part, to a narrower beam profile. The root-mean-square estimate of aberration after propagation through the simulated body wall is shown to be low (23.4 ns), which is consistent with previous reports of aberration measured experimentally in a human body wall. The spatial coherence measured at the transducer surface indicates that a transducer array element size of < 0.81λ would be required to fully sample the acoustic field. These first simulated three dimensional ultrasound images based directly on propagation physics provide a platform to investigate the sources of image degradation in three dimensions. A detailed charaterization of these sources of image degradation, including reverberation clutter, are included in Part II of this paper.

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Blocked Elements in 1-D and 2-D Arrays—Part I: Detection and Basic Compensation on Simulated and In Vivo Targets

Cited by 11 publications

References 19 publications

Unsupervised clustering method to convert high-resolution magnetic resonance volumes to three-dimensional acoustic models for full-wave ultrasound simulations

Unsupervised clustering method to convert high-resolution magnetic resonance volumes to three-dimensional acoustic models for full-wave ultrasound simulations

Ultrasound imaging with three dimensional full-wave nonlinear acoustic simulations. Part 2: sources of image degradation in intercostal imaging

Ultrasound imaging of the human body with three dimensional full-wave nonlinear acoustics. Part 1: simulations methods

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