The Experts below are selected from a list of 14568 Experts worldwide ranked by ideXlab platform

Joseph V. Hajnal - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Aperture, Depth, and Acoustic Clutter on the Performance of Coherent Multi-Transducer Ultrasound Imaging
    Applied Sciences, 2020
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Robert J. Eckersley, Joseph V. Hajnal
    Abstract:

    Transducers with a larger Aperture size are desirable in ultrasound imaging to improve resolution and image quality. A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through the coherent combination of multiple transducers. In this study, the discontinuous extended Aperture created by CoMTUS and its performance for deep imaging and through layered media are investigated by both simulations and experiments. Typical image quality metrics—resolution, contrast and contrast-to-noise ratio—are evaluated and compared with a standard single probe imaging system. Results suggest that the image performance of CoMTUS depends on the relative spatial location of the arrays. The resulting Effective Aperture significantly improves resolution, while the separation between the arrays may degrade contrast. For a limited gap in the Effective Aperture (less than a few centimetres), CoMTUS provides benefits to image quality compared to the standard single probe imaging system. Overall, CoMTUS shows higher sensitivity and reduced loss of resolution with imaging depth. In general, CoMTUS imaging performance was unaffected when imaging through a layered medium with different speed of sound values and resolution improved up to 80% at large imaging depths.

  • Impact of Aperture, depth, and acoustic clutter on performance of Coherent Multi-Transducer Ultrasound imaging.
    arXiv: Medical Physics, 2020
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Robert J. Eckersley, Joseph V. Hajnal
    Abstract:

    Transducers with larger Aperture size are desirable in ultrasound imaging to improve resolution and image quality. A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through coherent combination of multiple transducers. In this study, the discontinuous extended Aperture created by CoMTUS and its performance for deep imaging and through layered-media are investigated by both simulations and experiments. Typical image quality metrics - resolution, contrast and contrast-to-noise ratio - are evaluated and compared with a standard single probe imaging system. Results suggest that, the image performance of CoMTUS depends on the relative spatial location of the arrays. The resulting Effective Aperture significantly improves resolution, while the separation between the arrays may degrade contrast. For a limited gap in the Effective Aperture (less than few centimetres), CoMTUS provides benefits to image quality compared to standard single probe imaging system. Overall, CoMTUS shows higher sensitivity and reduced loss of resolution with imaging depth. In general, CoMTUS imaging performance was unaffected when imaging through a layered-medium with different speed of sound values and resolution improved up to 80% at large imaging depths.

  • Coherent Multi-Transducer Ultrasound Imaging with Microbubble Contrast Agents
    2019 IEEE International Ultrasonics Symposium (IUS), 2019
    Co-Authors: Kirsten Christensen-jeffries, Laura Peralta, Michael Reinwald, Joseph V. Hajnal, Robert J. Eckersley
    Abstract:

    A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through coherent combination of multiple transducers. The resulting larger Effective Aperture improves the ultrasound imaging performance. The optimal beamforming parameters, which include the transducer locations and the average speed of sound in the medium, are deduced by maximizing the coherence of the received radio frequency data by cross-correlation. In this technique, the detection of multiple isolated point-like targets in the overlap of the insonated regions is mandatory to determine the relative probe-to-probe position. This study proposes the use of microbubbles to generate the point-like targets that the CoMTUS approach requires. The first phantom images produced using CoMTUS and microbubbles are presented here.

  • Extension of Coherent Multi-Transducer Ultrasound Imaging with Diverging Waves
    2019 IEEE International Ultrasonics Symposium (IUS), 2019
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Joseph V. Hajnal, Robert J. Eckersley
    Abstract:

    The assessment of ultrasound images is hampered by limited spatial resolution and view-dependent artifacts. Both limitations depend on the small Aperture of the transducers used in clinical practice, and may potentially be overcome by extending the Effective Aperture. The coherent multi-transducer ultrasound (CoMTUS) imaging method enables an extended Effective Aperture through coherent combination of multiple transducers. In this work, CoMTUS, originally developed and validated using plane waves, is extended to diverging wave imaging to widen the field of view, which, in CoMTUS, is limited to the intersection of the combined field of views. First phantom images produced using CoMTUS with diverging waves are presented here. Results show that CoMTUS with diverging waves has the potential to improve ultrasound image quality, improving resolution and target detectability. Compared with coherent DW compounding using a single probe, there is an averaged improvement in resolution of 26% and 2.3 dB increment in contrast.

Hae-kwon Jeong - One of the best experts on this subject based on the ideXlab platform.

  • Facile synthesis of Cd-substituted zeolitic-imidazolate framework Cd-ZIF-8 and mixed-metal CdZn-ZIF-8
    Microporous and Mesoporous Materials, 2018
    Co-Authors: Liya Semenchenko, Maria Fernanda Ballesteros Rivas, Víctor Varela-guerrero, Hae-kwon Jeong
    Abstract:

    Abstract Zeolitic-imidazole framework ZIF-8 has attracted tremendous interests for the high-resolution kinetic separation of propylene/propane mixture due to its Effective Aperture size in between the sizes of propylene and propane molecules. It is of great interest to fine-tune the Effective Aperture size of ZIF-8 either to improve its propylene/propane separation performances or to extend its use to the separation of other gas mixtures. It has been shown that substituting Zn with other metal nodes (e.g. Co) is a potential means to fine-tune the Effective Aperture size of ZIF-8. Here, we attempt to introduce another metal center, Cd, into ZIF-8 in a facile and scalable manner. Phase-pure Cd-ZIF-8 was successfully synthesized in methanol using a conventional solvothermal method, although it showed a narrow synthesis window. The presence of an organic base (triethylamine, TEA) was found critical not only for the facile synthesis of phase-pure Cd-ZIF-8 but also for the suppression of its phase transformation. A battery of characterizations including single-crystal X-ray structure solutions confirmed that the Effective Aperture size of Cd-ZIF-8 is the largest among its iso-structures (Zn-ZIF-8 and Co-ZIF-8). Finally, for the first time, mixed-metal CdZn-ZIF-8 crystals with various Cd/Zn ratios were solvothermally synthesized, demonstrating a further opportunity for varying the Effective Aperture sizes of ZIF-8 and its iso-structures.

Laura Peralta - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Aperture, Depth, and Acoustic Clutter on the Performance of Coherent Multi-Transducer Ultrasound Imaging
    Applied Sciences, 2020
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Robert J. Eckersley, Joseph V. Hajnal
    Abstract:

    Transducers with a larger Aperture size are desirable in ultrasound imaging to improve resolution and image quality. A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through the coherent combination of multiple transducers. In this study, the discontinuous extended Aperture created by CoMTUS and its performance for deep imaging and through layered media are investigated by both simulations and experiments. Typical image quality metrics—resolution, contrast and contrast-to-noise ratio—are evaluated and compared with a standard single probe imaging system. Results suggest that the image performance of CoMTUS depends on the relative spatial location of the arrays. The resulting Effective Aperture significantly improves resolution, while the separation between the arrays may degrade contrast. For a limited gap in the Effective Aperture (less than a few centimetres), CoMTUS provides benefits to image quality compared to the standard single probe imaging system. Overall, CoMTUS shows higher sensitivity and reduced loss of resolution with imaging depth. In general, CoMTUS imaging performance was unaffected when imaging through a layered medium with different speed of sound values and resolution improved up to 80% at large imaging depths.

  • Impact of Aperture, depth, and acoustic clutter on performance of Coherent Multi-Transducer Ultrasound imaging.
    arXiv: Medical Physics, 2020
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Robert J. Eckersley, Joseph V. Hajnal
    Abstract:

    Transducers with larger Aperture size are desirable in ultrasound imaging to improve resolution and image quality. A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through coherent combination of multiple transducers. In this study, the discontinuous extended Aperture created by CoMTUS and its performance for deep imaging and through layered-media are investigated by both simulations and experiments. Typical image quality metrics - resolution, contrast and contrast-to-noise ratio - are evaluated and compared with a standard single probe imaging system. Results suggest that, the image performance of CoMTUS depends on the relative spatial location of the arrays. The resulting Effective Aperture significantly improves resolution, while the separation between the arrays may degrade contrast. For a limited gap in the Effective Aperture (less than few centimetres), CoMTUS provides benefits to image quality compared to standard single probe imaging system. Overall, CoMTUS shows higher sensitivity and reduced loss of resolution with imaging depth. In general, CoMTUS imaging performance was unaffected when imaging through a layered-medium with different speed of sound values and resolution improved up to 80% at large imaging depths.

  • Coherent Multi-Transducer Ultrasound Imaging with Microbubble Contrast Agents
    2019 IEEE International Ultrasonics Symposium (IUS), 2019
    Co-Authors: Kirsten Christensen-jeffries, Laura Peralta, Michael Reinwald, Joseph V. Hajnal, Robert J. Eckersley
    Abstract:

    A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through coherent combination of multiple transducers. The resulting larger Effective Aperture improves the ultrasound imaging performance. The optimal beamforming parameters, which include the transducer locations and the average speed of sound in the medium, are deduced by maximizing the coherence of the received radio frequency data by cross-correlation. In this technique, the detection of multiple isolated point-like targets in the overlap of the insonated regions is mandatory to determine the relative probe-to-probe position. This study proposes the use of microbubbles to generate the point-like targets that the CoMTUS approach requires. The first phantom images produced using CoMTUS and microbubbles are presented here.

  • Extension of Coherent Multi-Transducer Ultrasound Imaging with Diverging Waves
    2019 IEEE International Ultrasonics Symposium (IUS), 2019
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Joseph V. Hajnal, Robert J. Eckersley
    Abstract:

    The assessment of ultrasound images is hampered by limited spatial resolution and view-dependent artifacts. Both limitations depend on the small Aperture of the transducers used in clinical practice, and may potentially be overcome by extending the Effective Aperture. The coherent multi-transducer ultrasound (CoMTUS) imaging method enables an extended Effective Aperture through coherent combination of multiple transducers. In this work, CoMTUS, originally developed and validated using plane waves, is extended to diverging wave imaging to widen the field of view, which, in CoMTUS, is limited to the intersection of the combined field of views. First phantom images produced using CoMTUS with diverging waves are presented here. Results show that CoMTUS with diverging waves has the potential to improve ultrasound image quality, improving resolution and target detectability. Compared with coherent DW compounding using a single probe, there is an averaged improvement in resolution of 26% and 2.3 dB increment in contrast.

Robert J. Eckersley - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Aperture, Depth, and Acoustic Clutter on the Performance of Coherent Multi-Transducer Ultrasound Imaging
    Applied Sciences, 2020
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Robert J. Eckersley, Joseph V. Hajnal
    Abstract:

    Transducers with a larger Aperture size are desirable in ultrasound imaging to improve resolution and image quality. A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through the coherent combination of multiple transducers. In this study, the discontinuous extended Aperture created by CoMTUS and its performance for deep imaging and through layered media are investigated by both simulations and experiments. Typical image quality metrics—resolution, contrast and contrast-to-noise ratio—are evaluated and compared with a standard single probe imaging system. Results suggest that the image performance of CoMTUS depends on the relative spatial location of the arrays. The resulting Effective Aperture significantly improves resolution, while the separation between the arrays may degrade contrast. For a limited gap in the Effective Aperture (less than a few centimetres), CoMTUS provides benefits to image quality compared to the standard single probe imaging system. Overall, CoMTUS shows higher sensitivity and reduced loss of resolution with imaging depth. In general, CoMTUS imaging performance was unaffected when imaging through a layered medium with different speed of sound values and resolution improved up to 80% at large imaging depths.

  • Impact of Aperture, depth, and acoustic clutter on performance of Coherent Multi-Transducer Ultrasound imaging.
    arXiv: Medical Physics, 2020
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Robert J. Eckersley, Joseph V. Hajnal
    Abstract:

    Transducers with larger Aperture size are desirable in ultrasound imaging to improve resolution and image quality. A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through coherent combination of multiple transducers. In this study, the discontinuous extended Aperture created by CoMTUS and its performance for deep imaging and through layered-media are investigated by both simulations and experiments. Typical image quality metrics - resolution, contrast and contrast-to-noise ratio - are evaluated and compared with a standard single probe imaging system. Results suggest that, the image performance of CoMTUS depends on the relative spatial location of the arrays. The resulting Effective Aperture significantly improves resolution, while the separation between the arrays may degrade contrast. For a limited gap in the Effective Aperture (less than few centimetres), CoMTUS provides benefits to image quality compared to standard single probe imaging system. Overall, CoMTUS shows higher sensitivity and reduced loss of resolution with imaging depth. In general, CoMTUS imaging performance was unaffected when imaging through a layered-medium with different speed of sound values and resolution improved up to 80% at large imaging depths.

  • Coherent Multi-Transducer Ultrasound Imaging with Microbubble Contrast Agents
    2019 IEEE International Ultrasonics Symposium (IUS), 2019
    Co-Authors: Kirsten Christensen-jeffries, Laura Peralta, Michael Reinwald, Joseph V. Hajnal, Robert J. Eckersley
    Abstract:

    A coherent multi-transducer ultrasound imaging system (CoMTUS) enables an extended Effective Aperture through coherent combination of multiple transducers. The resulting larger Effective Aperture improves the ultrasound imaging performance. The optimal beamforming parameters, which include the transducer locations and the average speed of sound in the medium, are deduced by maximizing the coherence of the received radio frequency data by cross-correlation. In this technique, the detection of multiple isolated point-like targets in the overlap of the insonated regions is mandatory to determine the relative probe-to-probe position. This study proposes the use of microbubbles to generate the point-like targets that the CoMTUS approach requires. The first phantom images produced using CoMTUS and microbubbles are presented here.

  • Extension of Coherent Multi-Transducer Ultrasound Imaging with Diverging Waves
    2019 IEEE International Ultrasonics Symposium (IUS), 2019
    Co-Authors: Laura Peralta, Alessandro Ramalli, Michael Reinwald, Joseph V. Hajnal, Robert J. Eckersley
    Abstract:

    The assessment of ultrasound images is hampered by limited spatial resolution and view-dependent artifacts. Both limitations depend on the small Aperture of the transducers used in clinical practice, and may potentially be overcome by extending the Effective Aperture. The coherent multi-transducer ultrasound (CoMTUS) imaging method enables an extended Effective Aperture through coherent combination of multiple transducers. In this work, CoMTUS, originally developed and validated using plane waves, is extended to diverging wave imaging to widen the field of view, which, in CoMTUS, is limited to the intersection of the combined field of views. First phantom images produced using CoMTUS with diverging waves are presented here. Results show that CoMTUS with diverging waves has the potential to improve ultrasound image quality, improving resolution and target detectability. Compared with coherent DW compounding using a single probe, there is an averaged improvement in resolution of 26% and 2.3 dB increment in contrast.

Liya Semenchenko - One of the best experts on this subject based on the ideXlab platform.

  • Facile synthesis of Cd-substituted zeolitic-imidazolate framework Cd-ZIF-8 and mixed-metal CdZn-ZIF-8
    Microporous and Mesoporous Materials, 2018
    Co-Authors: Liya Semenchenko, Maria Fernanda Ballesteros Rivas, Víctor Varela-guerrero, Hae-kwon Jeong
    Abstract:

    Abstract Zeolitic-imidazole framework ZIF-8 has attracted tremendous interests for the high-resolution kinetic separation of propylene/propane mixture due to its Effective Aperture size in between the sizes of propylene and propane molecules. It is of great interest to fine-tune the Effective Aperture size of ZIF-8 either to improve its propylene/propane separation performances or to extend its use to the separation of other gas mixtures. It has been shown that substituting Zn with other metal nodes (e.g. Co) is a potential means to fine-tune the Effective Aperture size of ZIF-8. Here, we attempt to introduce another metal center, Cd, into ZIF-8 in a facile and scalable manner. Phase-pure Cd-ZIF-8 was successfully synthesized in methanol using a conventional solvothermal method, although it showed a narrow synthesis window. The presence of an organic base (triethylamine, TEA) was found critical not only for the facile synthesis of phase-pure Cd-ZIF-8 but also for the suppression of its phase transformation. A battery of characterizations including single-crystal X-ray structure solutions confirmed that the Effective Aperture size of Cd-ZIF-8 is the largest among its iso-structures (Zn-ZIF-8 and Co-ZIF-8). Finally, for the first time, mixed-metal CdZn-ZIF-8 crystals with various Cd/Zn ratios were solvothermally synthesized, demonstrating a further opportunity for varying the Effective Aperture sizes of ZIF-8 and its iso-structures.