-
Dalen, Håvard
(2024).
Sharing of sensitive data.
-
Rye, Cathrine Sæthern & Dalen, Håvard
(2024).
Kvalitet på kardiovaskulære diagnoser i sykehus.
-
Dalen, Håvard
(2024).
Kunstig intelligens ved ekkokardiografi.
-
Dalen, Håvard
(2024).
Forskning som endrer klinisk praksis.
-
Dalen, Håvard
(2024).
Hjertefysiologi og rehabilitering.
-
Viggen, Erlend Magnus & Arnestad, Håvard
(2023).
Why leaky flexural plate waves misbehave at low frequencies.
-
Diez, Anja; Johansen, Tonni Franke & Viggen, Erlend Magnus
(2023).
From 3D to 1D – effective numerical modelling of pulse-echo measurements in pipes.
-
Viggen, Erlend Magnus
(2023).
Setting the story straight about how vibrating surfaces produce sound.
Show summary
Can all vibrating surfaces produce sound in an adjacent fluid? This is a basic question in acoustics. Books and courses teach that the nature of the pressure wave generated by a vibration depends on the ratio between the vibration's speed and the fluid's sound speed: Supersonic vibrations (where the vibration moves faster than the sound speed) radiate sound waves into the fluid, while subsonic vibrations (where the vibration moves slower) generate evanescent pressure waves that do not radiate and cling to the surface. During an applied research project, however, we found results at odds with this prevailing view, indicating that subsonic vibrations can also radiate sound waves. Furthermore, a handful of articles over the last 30 years have also found similar results. While these results challenge the prevailing view of sound radiation, no full fundamental physical explanation of this phenomenon was available. We provide this missing explanation by taking energy conservation fully into account in a quite straightforward radiation model. This model balances the sound wave radiated into the fluid with a necessary attenuation of the guided wave underlying the vibration. While this attenuation is neglected by the majority of explanations in the literature, it is the key to explaining subsonic sound radiation, because attenuated vibrations produce inhomogeneous sound waves that always radiate. We find that subsonic vibrations can radiate sound waves in many situations, depending on the properties of the guided wave and the fluid medium.
-
Le, Hoang Duy; Manh, Tung & Hoff, Lars
(2023).
A novel wide-band design of dual-frequency transducer based on PZT-PVDF for super harmonic imaging.
-
Siu, Hoi Yi; Hoff, Lars & Frijlink, Martijn
(2023).
High Temperature Performance of 3 MHz 36° Y-Cut Lithium Niobate Ultrasonic Transducer for Non-Destructive Testing at 550 °C.
-
-
Wifstad, Sigurd Vangen; Indimath, Shivanandan; Bryon, Vincent; Avdal, Jørgen; Løvstakken, Lasse & Måsøy, Svein-Erik
[Show all 7 contributors for this article]
(2023).
Can we use Deep Learning to extract important information from poor resolution Doppler images?
-
Wifstad, Sigurd Vangen; Kildahl, Henrik Agerup; Holte, Espen; Grenne, Bjørnar Leangen; Dalen, Håvard & Løvstakken, Lasse
(2023).
Automatic Jet Flow Convergence Detection and Quantification from 2D Color Doppler Flow Using Deep Learning.
-
Bryon, Vincent; Wifstad, Sigurd Vangen; Hu, Jieyu; Grønli, Thomas & Løvstakken, Lasse
(2023).
Automated Patient-Specific Left Ventricular Simulations for Cardiac Function Evaluation Using Image-Based Computational Fluid Dynamics and Color Flow Imaging.
-
Bryon, Vincent; Wifstad, Sigurd Vangen; Hu, Jieyu; Grønli, Thomas & Løvstakken, Lasse
(2023).
Simulating Blood Flow in the Heart: Enhancing Color Flow Imaging with Computational Fluid Dynamics.
-
-
Fadnes, Solveig
(2023).
Vector Flow Imaging and extracted flow features.
-
Fadnes, Solveig
(2023).
High Frame Rate Imaging in Pediatric and Fetal Medicine - Opportunities and Challenges.
Show summary
This was an invited talk to the IEEE International Ultrasonics Symposium 2023 in Montréal, Canada. The talk summarized the research possibilities in pediatric and fetal medicine given by high frame rate imaging with focus on the visualization and quantification of intracardiac blood flow. Current clinical state-of-the-art imaging technology was demonstrated, and both the opportunities of new pathophysiological knowledge and diagnostic tools, and the inherent challenges of high-frame-rate imaging was discussed.
-
-
-
Sæbø, Sigbjørn; Dalen, Håvard; Nyberg, John; Jakobsen, Even Olav; Nes, Bjarne Martens & Grenne, Bjørnar Leangen
[Show all 8 contributors for this article]
(2023).
The relation between left atrial and left ventricular size in a healthy population.
-
Holte, Espen
(2023).
Implementering av guidelines - når anbefalinger utfordrer kapasitet?
-
-
-
-
Dalen, Håvard
(2023).
Bioprotese med høy hastighet. HALT? Hva gjør vi?
-
-
Nyberg, John; Jakobsen, Even Olav; Østvik, Andreas; Holte, Espen; Stølen, Stian & Løvstakken, Lasse
[Show all 8 contributors for this article]
(2023).
Determinants of left atrial reservoir strain in a large healthy population.
-
Pettersen, Håkon Neergaard; Sæbø, Sigbjørn; Smistad, Erik; Pasdeloup, David Francis Pierre; Stølen, Stian Bergseng & Grenne, Bjørnar Leangen
[Show all 9 contributors for this article]
(2023).
Real-time guiding by deep learning during echocardiography to reduce left ventricular foreshortening and measurement variability.
-
Pettersen, Håkon Neergaard; Sæbø, Sigbjørn; Pasdeloup, David Francis Pierre; Smistad, Erik; Østvik, Andreas & Olaisen, Sindre Hellum
[Show all 14 contributors for this article]
(2023).
The Impact of Real-time Guiding by Deep Learning on Inter-operator Variability of Left Ventricular Function Measurements.
-
Olaisen, Sindre Hellum
(2023).
AI-based measurements in echocardiography, clinical results.
-
Shur, Michael S.; Liu, Xueqing & Ytterdal, Trond
(2023).
Switching Characteristics of GaN Power Transistors.
-
Shur, Michael S.; Liu, Xueqing & Ytterdal, Trond
(2023).
Phase-sensitive Silicon CMOS TeraFETs.
-
Liu, Xueqing; Ytterdal, Trond & Shur, Michael S.
(2023).
Compact SPICE models for TeraFETs.
-
Balasubramanian, Linknath Surya; Cochran, Zachary; Rizkalla, Maher; Lee, John & Ytterdal, Trond
(2023).
Ultra Low-Power Low-Noise GNRFET Wideband Amplifier for Cryogenic Applications.
-
Kasongo, Muana; Ytterdal, Trond; Lee, John; Rizkalla, Maher & Kumar, Mukesh
(2023).
Evaluation of Leakage Currents in Memristor Crossbar Arrays.
-
Balasubramanian, Linknath Surya; Rizkalla, Maher; Lee, John; Ytterdal, Trond & Kumar, Mukesh
(2023).
Towards No Penalty Control Hazard Handling.
-
Gopinath, Anoop; Ytterdal, Trond; Yadhav, Avinash; Lee, John; Rizkalla, Maher & Kumar, Mukesh
(2023).
SRAM Vmin Scaling Via Negative Wordline.
-
Salte, Ivar Mjåland; Østvik, Andreas; Olaisen, Sindre Hellum; Karlsen, Sigve; Dahlslett, Thomas & Smistad, Erik
[Show all 13 contributors for this article]
(2023).
Response to “Minimal Detectable Change and Reproducibility of Echocardiographic Strain: Implications for Clinical Practice”.
Journal of the American Society of Echocardiography.
ISSN 0894-7317.
doi:
10.1016/j.echo.2023.08.017.
-
Måsøy, Svein-Erik; Dénarié, Bastien Emmanuel; Sørnes, Anders; Holte, Espen; Grenne, Bjørnar Leangen & Espeland, Torvald
[Show all 10 contributors for this article]
(2023).
Aberration correction in 3D echocardiography
.
Show summary
3D imaging is increasingly used in echocardiography. However, aberrations caused by sound speed variations in the body wall, degrades image quality, thereby compromising accurate diagnosis. Research into methods for compensating aberrations in pulse-echo imaging, referred to as aberration correction (AC), has been ongoing for more than 40 years. An AC algorithm has been developed and implemented to run real-time on a clinical ultrasound system for both 2D and 3D imaging. The algorithm estimates and corrects arrival time errors across all subapertures in a matrix array probe. A clinical trial has been carried out with the aim to evaluate the efficacy of our AC algorithm in improving image quality for 3D transthoracic echocardiography.
-
Wangensteen, Magnus; Johansen, Tonni Franke; Fatemi, Ali & Viggen, Erlend Magnus
(2023).
Ultrasonic Guided Waves and Machine Learning for Corrosion Monitoring in Steel Pipes.
Show summary
In a pipe, a circumferentially travelling ultrasonic wave will gather information about the properties and boundaries of the propagation medium. However, the compounded effects of diagnostic features like uniform pipe wall thinning, surface roughness, regional depressions, and pit developments are difficult to separate using traditional methods. Therefore, this study proposes an approach using artificial neural networks to estimate the diagnostic features of interest.
This study is based on ultrasound simulations and synthetic data. The synthetic data is recorded at a set of transducer positions at the outer pipe wall. The resulting traces are then combined into 2D images where each vertical line represents a trace and thus a transducer location. The resulting images are used to train a neural network to extract relevant features.
Diagnostic features for mean and minimum thickness, as well as roughness, are quite accurately estimated. Features for depth and location of depressions and depth of pits are also informative but less accurate.
-
Hu, Jieyu; Smistad, Erik; Grenne, Bjørnar Leangen; Holte, Espen; Dalen, Håvard & Løvstakken, Lasse
(2023).
Left-Ventricular Volume Estimation in Contrast-Enhanced Echocardiography Using Deep Learning.
-
Normannsen, Sølvi W. & Måsøy, Svein-Erik
(2023).
Forskere kan takke gamere for bedre ultralydbilder av hjertet.
[Business/trade/industry journal].
Gemini.no.
Show summary
Spillindustriens jag etter superraske mikroprosessorer har hjulpet norske forskere til å løse et 40 år gammelt ultralyd-problem.
-
Pasdeloup, David Francis Pierre; Østvik, Andreas; Olaisen, Sindre Hellum; Skogvoll, Eirik; Dalen, Håvard & Løvstakken, Lasse
(2023).
Automated measurements with AI: the gap between proof-of-concept and clinical use.
-
Smistad, Erik
(2023).
Medisinsk bildeanalyse med kunstig intelligens.
-
Rindal, Ole Marius Hoel; Vrålstad, Anders Emil; Bjåstad, Tore Grüner; Sørnes, Anders Rasmus & Måsøy, Svein-Erik
(2023).
Improving Image Quality Degradation due to Blocked Array in Cardiac Ultrasound Imaging.
Show summary
The footprint of a cardiac ultrasound (US) probe is designed to fit the size of the intercostal space between the ribs to avoid ribs blocking the US energy. Some patients will have an intercostal space narrower than the footprint, making array blockage inevitable. In some cases, the clinician may be forced to place the probe in a position subject to rib blockage to achieve the desired anatomical view. Firstly, we demonstrate that such rib blockages reduce the image quality and lead to depth-varying geometrical distortions, potentially tilting structures and reducing resolution. Secondly, we demonstrate that compensating for the blocked array in the retrospective transmit beamforming (RTB) corrects most of the unwanted effects and improves image quality.
-
Vrålstad, Anders Emil; Kvalevåg, Magnus; Rindal, Ole Marius Hoel & Måsøy, Svein-Erik
(2023).
Universal REFoCUS with Spatial Weighting.
Show summary
The REFoCUS algorithm decomposes any arbitrary transmit wave into its Huygens-Fresnel components allowing Synthetic Transmit Aperture (STA) beamforming. The STA dataset is found by advancing the backscattered channel data by the applied transmit (Tx) delay and summing across Tx events. This simple advance-and-sum, also called adjoint inversion in frequency domain, has shown image quality similar to true STA beamforming for phased array sequences, but showed artifacts for sequences with walking aperture [1]. The artifacts were suppressed by regularizing the inversion at the cost of SNR [2]. Our time-domain implementation with pixel dependent apodization aims to generalize the REFoCUS method for all scan setups without introducing artifacts. The apodization is based on the directivity limitations of transducer elements, and it also works for 2D arrays using Sub-Aperture (SAP) technology.
-
Rindal, Ole Marius Hoel; Fiorentini, Stefano; Avdal, Jørgen; Austeng, Andreas & Rodriguez Molares, Alfonso
(2023).
The Generalized Beamformer in the UltraSound ToolBox.
Show summary
Access to channel data, and real-time processing of such, have left us a landscape filled with beamforming techniques often using specific wavefronts with specific reconstruction algorithms. This implies high costs for code maintenance and makes it difficult to compare different techniques. We demonstrate a generalized beamformer (GB) to reconstruct any transmit (tx) waveform from any probe into a defined grid of pixels. It covers linear and sector scans, both steered and stepped tx and even complex beamforming such as multiple line acquisition (MLA) and retrospective tx beamforming (RTB). Also, we show how the GB can be utilized to improve the channel data used for adaptive beamforming.
-
Gopinath, Anoop; Ytterdal, Trond; Lee, John; Rizkalla, Maher & Kumar, Mukesh
(2023).
SRAM Process and Debug Sensor.
-
-
Måsøy, Svein-Erik
(2022).
Aberration correction in medical ultrasound imaging
.
-
-
Hu, Jieyu; Smistad, Erik; Salte, Ivar Mjåland; Dalen, Håvard & Løvstakken, Lasse
(2022).
Exploiting temporal information in echocardiography for improved image segmentation.
-
Yadhav, Avinash; Rizkalla, Maher; Ytterdal, Trond; Lee, John H.; Balasubramanian, Linknath Surya & Gopinath, Anoop
(2022).
Evaluation of FinFET in Ultra Low Power ALU.
-
Liu, Xueqing; Shur, Michael S. & Ytterdal, Trond
(2022).
Optimization of Si CMOS TeraFETs for 300 GHz band operation.
-
Shur, Michael S.; Liu, Xueqing & Ytterdal, Trond
(2022).
Improved Thin Film Transistor Model Predicts TFT Operation in the THz Range.
-
Shur, Michael S.; Liu, Xueqing & Ytterdal, Trond
(2022).
Plasmonic Si CMOS TeraFETs for detection, mixing, and processing sub-THz radiation.
-
Pasdeloup, David Francis Pierre; Sæbø, Sigbjørn; Olaisen, Sindre Hellum; Pettersen, Håkon Neergaard; Østvik, Andreas & Holte, Espen
[Show all 11 contributors for this article]
(2022).
Real-Time Echocardiography Guidance for Optimized Apical Standard Views.
-
Pasdeloup, David Francis Pierre; Sæbø, Sigbjørn; Olaisen, Sindre Hellum; Pettersen, Håkon Neergaard; Østvik, Andreas & Holte, Espen
[Show all 11 contributors for this article]
(2022).
Real-Time Echocardiography Guidance for Optimized Apical Standard Views.
-
-
-
-
Pasdeloup, David Francis Pierre; Løvstakken, Lasse; Smistad, Erik & Dalen, Håvard
(2023).
Deep Learning in the Echocardiography Workflow: Challenges and Opportunities.
Norges teknisk-naturvitenskapelige universitet.
ISSN 978-82-326-7480-0.