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Beamformer for a Lensed Row–Column Array in 3-D Ultrasound Imaging
Ali Salari;Mélanie Audoin;Borislav Gueorguiev Tomov;Billy Y. S. Yiu;Erik Vilain Thomsen;Jørgen Arendt Jensen
Row-column (RC) arrays typically suffer from a limited field of view (FOV), with the imaging area confined to a rectangular region equal to the footprint of the probe. This limitation can be solved by using a diverging lens in front of the probe. Previous studies have introduced a thin lens model for beamforming lensed RC arrays, but this model inaccurately assumes the lens to be infinitely thin, ...Show More
Underestimation of Flow Velocity in 2-D Super-Resolution Ultrasound Imaging
Mostafa Amin Naji;Iman Taghavi;Erik Vilain Thomsen;Niels Bent Larsen;Jørgen Arendt Jensen
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Year: 2024 | Volume: 71, Issue: 12: Breaking the Resolution Barrier in Ultrasound | Journal Article |
Cited by: Papers (4)
Velocity estimation in ultrasound imaging is a technique to measure the speed and direction of blood flow. The flow velocity in small blood vessels, i.e., arterioles, venules, and capillaries, can be estimated using super-resolution ultrasound imaging (SRUS). However, the vessel width in SRUS is relatively small compared with the full-width-half-maximum of the ultrasound beam in the elevation dire...Show More
Super-Resolution Ultrasound Imaging Using the Erythrocytes—Part II: Velocity Images
Mostafa Amin Naji;Iman Taghavi;Mikkel Schou;Sebastian Kazmarek Præsius;Lauge Naur Hansen;Nathalie Sarup Panduro;Sofie Bech Andersen;Stinne Byrholdt Søgaard;Carsten Gundlach;Hans Martin Kjer;Borislav Gueorguiev Tomov;Erik Vilain Thomsen;Michael Bachmann Nielsen;Niels Bent Larsen;Anders Bjorholm Dahl;Charlotte Mehlin Sørensen;Jørgen Arendt Jensen
Super-resolution ultrasound imaging using the erythrocytes (SURE) has recently been introduced. The method uses erythrocytes as targets instead of fragile microbubbles (MBs). The abundance of erythrocyte scatterers makes it possible to acquire SURE data in just a few seconds compared with several minutes in ultrasound localization microscopy (ULM) using MBs. A high number of scatterers can reduce ...Show More
Super-Resolution Ultrasound Imaging Using the Erythrocytes—Part II: Velocity Images
Mostafa Amin Naji;Iman Taghavi;Mikkel Schou;Sebastian Kazmarek Præsius;Lauge Naur Hansen;Nathalie Sarup Panduro;Sofie Bech Andersen;Stinne Byrholdt Søgaard;Carsten Gundlach;Hans Martin Kjer;Borislav Gueorguiev Tomov;Erik Vilain Thomsen;Michael Bachmann Nielsen;Niels Bent Larsen;Anders Bjorholm Dahl;Charlotte Mehlin Sørensen;Jørgen Arendt Jensen
Super-Resolution Ultrasound Imaging Using the Erythrocytes—Part I: Density Images
Jørgen Arendt Jensen;Mostafa Amin Naji;Sebastian Kazmarek Præsius;Iman Taghavi;Mikkel Schou;Lauge Naur Hansen;Sofie Bech Andersen;Stinne Byrholdt Søgaard;Nathalie Sarup Panduro;Charlotte Mehlin Sørensen;Michael Bachmann Nielsen;Carsten Gundlach;Hans Martin Kjer;Anders Bjorholm Dahl;Borislav Gueorguiev Tomov;Martin Lind Ommen;Niels Bent Larsen;Erik Vilain Thomsen
A new approach for vascular super-resolution (SR) imaging using the erythrocytes as targets (SUper-Resolution ultrasound imaging of Erythrocytes (SURE) imaging) is described and investigated. SURE imaging does not require fragile contrast agent bubbles, making it possible to use the maximum allowable mechanical index (MI) for ultrasound scanning for an increased penetration depth. A synthetic aper...Show More
Super-Resolution Ultrasound Imaging Using the Erythrocytes—Part I: Density Images
Jørgen Arendt Jensen;Mostafa Amin Naji;Sebastian Kazmarek Præsius;Iman Taghavi;Mikkel Schou;Lauge Naur Hansen;Sofie Bech Andersen;Stinne Byrholdt Søgaard;Nathalie Sarup Panduro;Charlotte Mehlin Sørensen;Michael Bachmann Nielsen;Carsten Gundlach;Hans Martin Kjer;Anders Bjorholm Dahl;Borislav Gueorguiev Tomov;Martin Lind Ommen;Niels Bent Larsen;Erik Vilain Thomsen
Diverging Polymer Acoustic Lens Design for High-Resolution Row–Column Array Ultrasound Transducers
Mélanie Audoin;Ali Salari;Borislav Gueorguiev Tomov;Kasper Fløng Pedersen;Jørgen Arendt Jensen;Erik Vilain Thomsen
Spherical diverging acoustic lenses mounted on flat 2-D row–column-addressed (RCA) ultrasound transducers have shown the potential to extend the field of view (FOV) from a rectilinear to a curvilinear volume region and, thereby, enable 3-D imaging of large organs. Such lenses are usually designed for small aperture low-frequency transducers, which have limited resolution. Moreover, they are made o...Show More
Novel Diverging Acoustic Lens Geometries for Row-Column Array Transducers
Mélanie Audoin;Ali Salari;Borislav Gueorguiev Tomov;Jørgen Arendt Jensen;Erik Vilain Thomsen
2023 IEEE International Ultrasonics Symposium (IUS)
Year: 2023 | Conference Paper |
Cited by: Papers (2)
Double-curved diverging lenses are used to extend the Field of View (FOV) of flat 2D Row-Column Addressed (RCA) transducers, for performing real-time volumetric imaging of large organs. Such lenses are usually made in a spherical shape geometry, which poorly fits the square footprint of RCA arrays. In particular, for large arrays, the radius of curvature of the lens is constrained to increase sign...Show More
Recursive Imaging for Tracking High Density Scatterers in Super-Resolution Imaging
Mostafa Amin-Naji;Iman Taghavi;Niels Bent Larsen;Erik Vilain Thomsen;Charlotte Mehlin Sørensen;Jørgen Arendt Jensen
2023 IEEE International Ultrasonics Symposium (IUS)
Year: 2023 | Conference Paper |
Cited by: Papers (3)
A key component of super-resolution ultrasound imaging (SRI) is the detection and tracking of scatterers. These scatterers can be microbubbles (MBs) in SRI, or erythrocytes in SUper Resolution ultrasound imaging using Erythrocytes (SURE). To ensure the reliability of MBs tracking in SRI, the MBs must be sparse. However, the sparse distribution of the MBs necessitates several minutes of acquisition...Show More
Accurate Radiation Impedance Analysis for CMUT Design
Stine Løvholt Grue Pedersen;Andreas Spandet Havreland;Ole Hansen;Erik Vilain Thomsen
2022 IEEE International Ultrasonics Symposium (IUS)
Year: 2022 | Conference Paper |
Cited by: Papers (1)
The transducer resonance frequency is a key parameter for the field of ultrasound. The resonance frequency in vacuum is well understood, and an analytical expression for the center frequency in immersion was derived by Lamb in 1920 [1], however this expression has limited validity. Importantly, the model fails to cover plate aspect ratios needed by imaging requirements and met by recently fabricat...Show More
Synthetic Aperture High Quality B-mode Imaging with a Row-Column Array Compared to Linear Array Imaging
Jorgen Arendt Jensen;Mikkel Schou;Martin Lind Ommen;Kitty Steenberg;Erik Vilain Thomsen;Borislav G. Tomov;Nathalie Sarup Panduro;Charlotte Mehlin Sorensen;Matthias Bo Stuart
2022 IEEE International Ultrasonics Symposium (IUS)
Year: 2022 | Conference Paper |
Row-column (RC) matrix probes can yield 3-D volumetric imaging using a number of receiving elements similar to traditional linear arrays for commercial scanners. Some doubts have, however, been raised on the B-mode image quality of RC probes. It is hypothesized that synthetic aperture (SA) RC imaging can yield a better volumetric resolution than commercial spatially translated linear arrays, and a...Show More
Synthetic Aperture High Quality B-mode Imaging with a Row-Column Array Compared to Linear Array Imaging
Jorgen Arendt Jensen;Mikkel Schou;Martin Lind Ommen;Kitty Steenberg;Erik Vilain Thomsen;Borislav G. Tomov;Nathalie Sarup Panduro;Charlotte Mehlin Sorensen;Matthias Bo Stuart
Year: 2022 | Conference Paper |
Comparative Analysis of CMUT and PZT Transducers for Coded Excitation
Mudabbir Tufail Bhatti;Borislav Gueorguiev Tomov;Søren Elmin Diedrichsen;Matthias Bo Stuart;Erik Vilain Thomsen;Jørgen Arendt Jensen
2022 IEEE International Ultrasonics Symposium (IUS)
Year: 2022 | Conference Paper |
Coded excitation (CE) signals have the potential to greatly improve image quality and penetration depth by increasing the signal-to-noise ratio (SNR). However, CE can increase the operating temperature of a transducer beyond the safety limits defined by the International Electrotechnical Commission (IEC), and this has often limited the use of CE with Lead Zirconate Titanate (PZT) probes. Capacitiv...Show More
Diverging Polymer Lens Design and Fabrication for Row-Column Addressed Transducers
Mélanie Audoin;Borislav Gueorguiev Tomov;Kasper Fløng Pedersen;Jørgen Arendt Jensen;Erik Vilain Thomsen
2022 IEEE International Ultrasonics Symposium (IUS)
Year: 2022 | Conference Paper |
Cited by: Papers (3)
Double-curved diverging lenses mounted on flat 2D Row-Column Addressed (RCA) transducers have shown the potential to extend the Field of View (FOV) from a rectilinear to a curvilinear volume region and thereby enable real-time 3D imaging of large organs. Such lenses are usually made of off-the-shelf pieces of materials, which leaves no room for optimization. In this work, acoustic lenses have been...Show More
Compensation for Velocity Underestimation in 2D Super-Resolution Ultrasound
Iman Taghavi;Mostafa Amin-Naji;Mikkel Schou;Martin Lind Ommen;Kitty Steenberg;Niels Bent Larsen;Erik Vilain Thomsen;Jørgen Arendt Jensen
2022 IEEE International Ultrasonics Symposium (IUS)
Year: 2022 | Conference Paper |
Cited by: Papers (4)
Super-resolution ultrasound imaging (SRI) has shown the potential for visualization of the vasculature with sub-wavelength resolution. Microbubble (MB) tracking in SRI can improve image quality and enable velocity estimation. However, it is usually neglected that the size of the vessel might be relatively small compared to the full width half maximum resolution in the elevation direction (FWHMy) a...Show More
A Hand-Held 190+190 Row–Column Addressed CMUT Probe for Volumetric Imaging
Rune Sixten Grass;Mathias Engholm;Andreas Spandet Havreland;Christopher Beers;Martin Lind Ommen;Stine Løvholt Grue Pedersen;Lars Nordahl Moesner;Matthias Bo Stuart;Mudabbir Tufail Bhatti;Borislav G. Tomov;Jørgen Arendt Jensen;Erik Vilain Thomsen
This paper presents the design, fabrication, and characterization of a 190+190 row-column addressed (RCA) capacitive micromachined ultrasonic transducer (CMUT) array integrated in a custom hand-held probe handle. The array has a designed 4.5 MHz center frequency in immersion and a pitch of $95~\mu $ m which corresponds to $\approx ~\lambda $ /4. The array has a $2.14\times2.14$ cm $^{2}$ foo...Show More
A Hand-Held 190+190 Row–Column Addressed CMUT Probe for Volumetric Imaging
Rune Sixten Grass;Mathias Engholm;Andreas Spandet Havreland;Christopher Beers;Martin Lind Ommen;Stine Løvholt Grue Pedersen;Lars Nordahl Moesner;Matthias Bo Stuart;Mudabbir Tufail Bhatti;Borislav G. Tomov;Jørgen Arendt Jensen;Erik Vilain Thomsen
Anatomic and Functional Imaging Using Row–Column Arrays
Jørgen Arendt Jensen;Mikkel Schou;Lasse Thurmann Jørgensen;Borislav G. Tomov;Matthias Bo Stuart;Marie Sand Traberg;Iman Taghavi;Sigrid Huesebø Øygaard;Martin Lind Ommen;Kitty Steenberg;Erik Vilain Thomsen;Nathalie Sarup Panduro;Michael Bachmann Nielsen;Charlotte Mehlin Sørensen
Row–column (RC) arrays have the potential to yield full 3-D ultrasound imaging with a greatly reduced number of elements compared to fully populated arrays. They, however, have several challenges due to their special geometry. This review article summarizes the current literature for RC imaging and demonstrates that full anatomic and functional imaging can attain a high quality using synthetic ape...Show More
Anatomic and Functional Imaging Using Row–Column Arrays
Jørgen Arendt Jensen;Mikkel Schou;Lasse Thurmann Jørgensen;Borislav G. Tomov;Matthias Bo Stuart;Marie Sand Traberg;Iman Taghavi;Sigrid Huesebø Øygaard;Martin Lind Ommen;Kitty Steenberg;Erik Vilain Thomsen;Nathalie Sarup Panduro;Michael Bachmann Nielsen;Charlotte Mehlin Sørensen
Polysilicon on Quartz Substrate for Silicide Based Row-Column CMUTs
2021 IEEE International Ultrasonics Symposium (IUS)
Year: 2021 | Conference Paper |
This paper presents a new type of insulating substrate, polysilicon-on-quartz (POOQ), that can be used for wafer bonded capacitive micromachined ultrasonic transducers (CMUTs). The substrate is based on a quartz handle wafer on which a device layer of polysilicon is deposited. The polysilicon is polished to an average surface roughness below 0.2 nm which allows for wafer bonding. Fusion bonding of...Show More
Fabrication, Characterization and Modelling of Delay Line Based CMUTs
Kasper Fløng Pedersen;Andreas Spandet Havreland;Erik Vilain Thomsen
2021 IEEE International Ultrasonics Symposium (IUS)
Year: 2021 | Conference Paper |
This paper presents fabrication, characterization and modelling of delay-line based capacitive micromachined ultrasonic transducers (CMUT). CMUTs have been fabricated using standard semiconductor processes, the electrical frequency response has been modelled by an equivalent circuit diagram and excellent agreement between theory and measurement is observed. Finally, the electrical crosstalk betwee...Show More
Automatic optical failure detection on large ultrasonic arrays
2021 IEEE International Ultrasonics Symposium (IUS)
Year: 2021 | Conference Paper |
The search for improved resolution in super-resolution ultrasound (SRUS) imaging leads to larger ultrasound arrays and smaller elements. A current large row-column addressed (RCA) array spans $\approx 21\times 21\ \text{mm}^{2}$ with $190 +190$ elements separated by a kerf of $3\ \mu\mathrm{m}$. Increasing array dimensions and decreasing feature sizes not only makes fabrication more complex, but m...Show More
Analytical Deflection Profiles and Pull-In Voltage Calculations of Prestressed Electrostatic Actuated MEMS Structures
This paper presents a zeroth and first order perturbative analysis of prestressed electrostatic actuated Microelectromechanical systems (MEMS). Perturbation theory is used to calculate the deflection profile of various MEMS structures, from which the pull-in voltage is estimated using the weighed residual method, where both a Galerkin expression and a Dirac delta function have been used as weight ...Show More
Delay Line Separation of CMUT Elements
Andreas Spandet Havreland;Ole Hansen;Kasper Fløng Pedersen;Mathias Engholm;Erik Vilain Thomsen
2020 IEEE International Ultrasonics Symposium (IUS)
Year: 2020 | Conference Paper |
Cited by: Papers (3)
This paper presents a novel fabrication design for capacitive micromachined ultrasonic transducers (CMUT) that utilizes a designed delay line in the silicon substrate for element separation. All elements in this design are electrically connected through the substrate, however, high resistivity (> 10.000 Ωcm) float zone silicon is used for the substrate to suppress cross-talk between elements. The ...Show More
384 Channel Modular Ultrasonic CMUT Probe for Rapid Prototyping
Kasper F. Pedersen;Mathias Engholm;Andreas S. Havreland;Lars N. Moesner;Christopher Beers;Borislav G. Tomov;Jørgen A. Jensen;Erik V. Thomsen
2020 IEEE International Ultrasonics Symposium (IUS)
Year: 2020 | Conference Paper |
This paper presents the design and fabrication of a novel 384 channel modular ultrasonic probe for row-column addressed capacitive micromachined ultrasound transducers. The nose-piece and front-electronics can be freely interchanged in situ, allowing different combinations of transducer arrays and front-end architectures to be characterized and compared, without fabricating an entire probe for eac...Show More
Electrical Insulation of CMUT Elements Using DREM and Lapping
2020 IEEE International Ultrasonics Symposium (IUS)
Year: 2020 | Conference Paper |
Cited by: Papers (1)
This paper demonstrates a novel fabrication process to implement a capacitive micromachined ultrasound transducer (CMUT) into a laparoscope. Due to the limited space in the laparoscope, a new method for electrically contacting the transducer elements is required. Using a state-of-the-art high aspect ratio dry etching process called Deposit, Remove, Etch, Multistep (DREM), it is possible to separat...Show More
Investigating a CMUT's Ability to Achieve Non-linear Contrast Enhancement
Sigrid H. Øygard;Martin L. Ommen;Mathias Engholm;Mikkel Schou;S⊘ren E. Diederichsen;Erik V. Thomsen;Matthias Bo Stuart;J⊘rgen Arendt Jensen
2020 IEEE International Ultrasonics Symposium (IUS)
Year: 2020 | Conference Paper |
Capacitive micromachined ultrasonic transducers (CMUTs) are inherently non-linear and often believed to be unsuitable for non-linear contrast-enhanced ultrasound (CEUS) imaging. The ability of CMUTs to perform contrast-enhanced ultrasound imaging has been investigated by experimentally evaluating the contrast-to-noise ratio (CTR) and its variation with emitted pressure. This has been evaluated usi...Show More
Pull-in Analysis of CMUT Elements
Andreas Spandet Havreland;Mathias Engholm;Christoffer Vendelbo SØrensen;Erik Vilain Thomsen
2020 IEEE International Ultrasonics Symposium (IUS)
Year: 2020 | Conference Paper |
Cited by: Papers (3)
This paper presents a novel characterization method for the pull-in voltage of a Capacitive Micromachined Ultrasonic Transducer (CMUT) element. The presented method allows pull-in estimation of all CMUT cells contained in an element, which is in contrast to conventional methods that only allows for a pull-in average across an element. The methodology has been conducted on four different CMUT eleme...Show More
Large Scale High Voltage 192+192 Row-Column Addressed CMUTs Made with Anodic Bonding
Rune Sixten Grass;Kitty Steenberg;Andreas Spandet Havreland;Mathias Engholm;Erik Vilain Thomsen
2020 IEEE International Ultrasonics Symposium (IUS)
Year: 2020 | Conference Paper |
Cited by: Papers (4)
This work presents the fabrication process of anodically bonded 192+192 2D row-column addressed (RCA) capacitive micromachined ultrasonic transducer (CMUT) arrays. Four large 2.1 by 2.1 cm2 arrays with a resonance frequency of 7.5 MHz in water and λ/2 element pitch at 95 μm are shown successfully fabricated. The arrays exhibit a 100% bond yield by anodically bonding an SOI wafer to a borosilicate ...Show More
Detection and Localization of Ultrasound Scatterers Using Convolutional Neural Networks
Jihwan Youn;Martin Lind Ommen;Matthias Bo Stuart;Erik Vilain Thomsen;Niels Bent Larsen;Jørgen Arendt Jensen
Delay-and-sum (DAS) beamforming is unable to identify individual scatterers when their density is so high that their point spread functions overlap. This paper proposes a convolutional neural network (CNN)-based method to detect and localize high-density scatterers, some of which are closer than the resolution limit of delay-andsum (DAS) beamforming. A CNN was designed to take radio frequency chan...Show More
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