Browsing NTNU Open by Author "Løvstakken, Lasse"
Now showing items 1-20 of 43
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4D ultrasound vector flow imaging for intraventricular flow assessment
Wigen, Morten Smedsrud (Doctoral theses at NTNU;2019:38, Doctoral thesis, 2019)4D ultralyd vector flow avbildning for evaluering av blodstrøm i hjertet Ultralyd er den mest utbredte modaliteten for evaluering av hjertefunksjon grunnet tilgjengelighet, lav kostnad og sanntidsvisning. Ekkokardiografi ... -
A fast 4D B-spline framework for model-based reconstruction and regularization in vector flow imaging
Grønli, Thomas; Wigen, Morten Smedsrud; Segers, Patrick; Løvstakken, Lasse (Journal article; Peer reviewed, 2018)A generic framework for model-based regularization and reconstruction is described, with applications in a wide range of noisy measurement scenarios. The framework employs automatic differentiation and stochastic gradient ... -
A framework for the simulation and validation of acoustic fields from medical ultrasound transducers
Bakstad, Ole (Master thesis, 2012)The unified simulation framework for medical ultrasound, FieldSim, cur- rently supports linear and non-linear simulations by using Field II and Aber- sim, respectively. In this thesis the quasi-linear simulation tool, ... -
A Scientific Tool for Real-time Acquisition and Analysis of Cardiovascular Measurements: Including ultrasound and other physiological data sources
Wigen, Morten Smedsrud (Master thesis, 2013)En programvare for studier av karsystemet, for både eksperimentelle og kliniske forsøk, skal utvikles i denne oppgaven. Data fra både ultralyd og andre fysiologiske kilder, som trykk, blodstrøm og volum, skal kunne mottas ... -
A System for the Acquisition and Analysis of Invasive and Non-invasive Measurements used to quantify Cardiovascular Performance
Omejer, Ole Øvergaard (Master thesis, 2011)Invasive measurements of cardiac functioning allows for more accurate measures of cardiac functioning than non-invasive measurements. However, invasive measurements is often not available in clinical settings. By comparing ... -
Adaptive Clutter Filtering for Improved Measurement of Cardiac Blood Velocities
Vågsholm, Beate Haram (Master thesis, 2017)In ultrasound color flow images of the heart, irregular blood flow patterns might be an early indication of heart disease. The blood flow is possible to image using multi-dimensional blood velocity estimation like speckle ... -
Adaptive speckle tracking algorithms for improved ultrasound blood flow imaging
Drange, Linn Siri (Master thesis, 2013)This thesis will present several ways to further improve the robustness of the speckle tracking method. The speckle tracking algorithm was made more adaptive to the velocity changes over time, utilizing velocity estimates ... -
Age Estimation from B-mode Echocardiography with 3D Convolutional Neural Networks
Fiorito, Adrian Meidell (Master thesis, 2019)Ekkokardiografi er en ikke-invasiv og sikker metode som bruker ultralyd for avbildning av hjertet. Som på mange andre felt utfører metoder for dyp læring, spesifikt \textit{Convolutional neural networks} (CNNs), oppgaver ... -
Automatic Detection of Mitral Annular Plane Systolic Excursion from Transesophageal Echocardiography Using Deep Learning
Nordal, Trym (Master thesis, 2019)Perioperativ monitorering av hjertet til pasienter som gjennomgår operasjoner er nødvendig for å forsikre at hjertets funksjon gjennoprettes. I dag gjennomføres periopertiv monitorering av hjertet manuelt, og baserer seg ... -
Automatic interpretation of cement evaluation logs from cased boreholes using supervised deep neural networks
Viggen, Erlend Magnus; Merciu, Ioan Alexandru; Løvstakken, Lasse; Måsøy, Svein-Erik (Peer reviewed; Journal article, 2020)The integrity of cement in cased boreholes is typically evaluated using well logging. However, well logging results are complex and can be ambiguous, and decisions associated with significant risks may be taken based on ... -
Automatic intraoperative estimation of blood flow direction during neurosurgical interventions
Iversen, Daniel Høyer; Løvstakken, Lasse; Unsgård, Geirmund; Reinertsen, Ingerid (Journal article; Peer reviewed, 2018)Purpose In neurosurgery, reliable information about blood vessel anatomy and flow direction is important to identify, characterize, and avoid damage to the vasculature. Due to ultrasound Doppler angle dependencies and the ... -
Better Automatic Interpretation of Cement Evaluation Logs through Feature Engineering
Viggen, Erlend Magnus; Løvstakken, Lasse; Merciu, Ioan Alexandru; Måsøy, Svein-Erik (Chapter, 2021)We build systems to automatically interpret cement evaluation logs using supervised machine learning (ML). Such systems can provide instant rough interpretations that may then be used as a basis for human interpretation. ... -
Blood Speckle-Tracking Based on High–Frame Rate Ultrasound Imaging in Pediatric Cardiology
Nyrnes, Siri Ann; Fadnes, Solveig; Wigen, Morten Smedsrud; Mertens, Luc; Løvstakken, Lasse (Peer reviewed; Journal article, 2020)Background: Flow properties play an important role in cardiac function, remodeling, and morphogenesis but cannot be displayed in detail with today’s echocardiographic techniques. The authors hypothesized that blood ... -
Cardiac power integral: a new method for monitoring cardiovascular performance
Rimehaug, Audun Eskeland; Lyng, Oddveig; Nordhaug, Dag Ole; Løvstakken, Lasse; Aadahl, Petter; Kirkeby-Garstad, Idar (Journal article; Peer reviewed, 2013)Cardiac power (PWR) is the continuous product of flow and pressure in the proximal aorta. Our aim was to validate the PWR integral as a marker of left ventricular energy transfer to the aorta, by comparing it to stroke ... -
Clutter Filter Wave Imaging
Salles, Sebastien; Løvstakken, Lasse; Aase, Svein Arne; Bjåstad, Tore Grüner; Torp, Hans (Journal article; Peer reviewed, 2019)The elastic properties of human tissue can be evaluated through the study of mechanical wave propagation captured using high frame rate ultrasound imaging. Methods such as block-matching or phase-based motion estimation ... -
Combined 2-D Vector imaging and Tracking Doppler for improved vascular blood velocity quantification
Avdal, Jørgen; Løvstakken, Lasse; Torp, Hans; Ekroll, Ingvild Kinn (Journal article; Peer reviewed, 2017)Measurement of the maximum blood flow velocity is the primary means for determining the degree of carotid stenosis using ultrasound. The current standard for estimating the maximum velocity is Pulsed Wave (PW) Doppler with ... -
Data Adaptive 2-D Tracking Doppler for High-Resolution Spectral Estimation
Karabiyik, Yücel; Avdal, Jørgen; Ekroll, Ingvild Kinn; Fiorentini, Stefano; Torp, Hans; Løvstakken, Lasse (Peer reviewed; Journal article, 2019)Spectral broadening in pulsed-wave Doppler caused by the transit-time effect deteriorates the frequency resolution and may cause overestimation of maximum velocities in high-velocity blood flow regions and for large ... -
Deep learning applications in medical imaging - Deep Convolutional Generative adversarial networks
Dietrichson, Fabian (Master thesis, 2018)Medical imaging Medical imaging makes it possible to examine internal human tissue without performing surgery. Common medical imaging techniques include magnetic resonance (MR), computer tomography (CT), X-ray and ultrasound ... -
Detailed flow visualization in fetal and neonatal hearts using 2-D speckle tracking
Fadnes, Solveig; Nyrnes, Siri Ann; Wigen, Morten Smedsrud; Tegnander, Eva; Løvstakken, Lasse (Journal article, 2016)Two-dimensional blood speckle tracking has shown promise for measuring the complex flow patterns in neonatal hearts when based on linear array and high-frame-rate plane wave imaging. For phased array pediatric imaging, ... -
Enhanced analysis of ultrasonic impedance logs: Improved imaging and fluid channel detection
Hoff, Simon Andreas (Master thesis, 2020)Abstract: The aim of this thesis is to detect vertical features in the the casing cement of oil and gas wells by using pattern recognition techniques based on machine learning on ultrasonic log data. Detecting channels is ...