Lasse Løvstakken
Research fellow

Areas of interest:
Diagnostic ultrasound imaging - Blood flow detection, estimation and visualization; Beamformation; Signal and image processing.
Background:
MSc. Engineering Cybernetics, NTNU, 2002
PhD. Medical Technology, NTNU, 2007

Publications:

[Media]

1. O. Solheim O, T. Selbekk, L. Løvstakken, G.A. Tangen, V. Solberg, J. Cappelen, G. Unsgaard, Ser svulst i hypofysen, Adresseavisen, May 27, p.11, 2009
2. S. A. Nyrnes, L. Løvstakken, Ny ultralydmetode gir bedre blodstrømsbilder, Dagens medisin, suppl. IT-helse, s. 20-21, 2008 (2) (link)
3. S. A. Nyrnes, L. Løvstakken, Ny norsk ultralyd, Computerworld, 2008 (link)
4. S. A. Nyrnes, L. Løvstakken, Ny ultralydmetode hjelper barn, Verdens gang, 2008 (link)

[Technical papers]

1. T. D. Fredriksen, I. K. Ekroll, L. Lovstakken, and H. Torp, 2-D Tracking Doppler: A New Method to Limit Spectral Broadening in Pulsed Wave Doppler, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 60(9), pp. 1896-1905, Sept. 2013
2. D. H. Iversen, F. Lindseth, G. Unsgaard, H. Torp, and L. Lovstakken, Model-Based Correction of Velocity Measurements in Navigated 3-D Ultrasound Imaging During Neurosurgical Interventions, IEEE Transactions on Medical Imaging, vol. 32(9), pp. 1622-1631, Sept. 2013
3. B. Denarie, T. A. Tangen, I. K. Ekroll, N. Rolim, H. Torp, T. Bjastad, and L. Lovstakken, Coherent Plane Wave Compounding for Very High Frame Rate Ultrasonography of Rapidly Moving Targets, IEEE Transactions on Medical Imaging, vol. 32(7), pp. 1265-1276, July 2013
4. I. K. Ekroll, A. Swillens, P. Segers, T. Dahl, H. Torp, and L. Lovstakken, Simultaneous quantification of flow and tissue velocities based on multi-angle plane wave imaging, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol.60(4), pp. 727-738, April 2013
5. A. Swillens, M. De Witte, H. Nordgaard, , H. Nordgaard, L. Løvstakken, D. Van Loo, B. Trachet, J. Vierendeels, and P. Segers, Effect of the degree of LAD stenosis on "competitive flow" and flow field characteristics in LIMA-to-LAD bypass surgery, Medical & biological engineering & computing, June 2012;
6. I. K. Ekroll, H. Torp, and L. Lovstakken, Spectral doppler estimation utilizing 2-D spatial information and adaptive signal processing, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 59(6), pp. 1182-1192, June 2012
7. A. Swillens, G. De Santis, J. Degroote, L. Lovstakken, J. Vierendeels, and P. Segers, Accuracy of carotid strain estimates from ultrasonic wall tracking: a study based on multiphysics simulations and in vivo data, IEEE Trans. Medical Imaging, vol. 31(1), pp. 131-139, Jan. 2012
8. A. Swillens, P. Segers, and L. Lovstakken, Two-dimensional flow imaging in the carotid bifurcation using a combined speckle tracking and phase-shift estimator: a study based on ultrasound simulations and in vivo analysis, Ultrasound in Medicine and Biology, vol. 36(10), pp. 1722-1735, Oct. 2010
9. A. Swillens, J. Degroote, J. Vierendeels, L. Lovstakken, and P. Segers, A simulation environment for validating ultrasonic blood flow and vessel wall imaging based on fluid-structure interaction simulations: ultrasonic assessment of arterial distension and wall shear rate, Medical Physics, vol. 37(8), pp. 4318-4330, Aug. 2010
10. A. C. H. Yu and L. Lovstakken, Eigen-Based Clutter Filter Design for Ultrasound Color Flow Imaging: A Review, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 57(5), pp. 1096-1111, May 2010
11. T. Hergum, T. G. Bjåstad, L. Løvstakken, K. Kristoffersen, and H. Torp, Reducing Color Flow Artifacts caused by Parallel Beamforming, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 57(4), pp. 830-838, Apr. 2010
12. A. Swillens, P. Segers, H. Torp, and L. Løvstakken, Two-dimensional blood velocity estimation with ultrasound: speckle tracking versus crossed-beam vector Doppler based on flow simulations in a carotid bifurcation model, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 57(2), pp. 327-339, Feb. 2010
13. A. Swillens, T. De Schryver, L. Løvstakken, H. Torp, and P. Segers, Assessment of numerical simulation strategies for ultrasonic color blood flow imaging, based on a computer and experimental model of the carotid artery, Annals of Biomedical Engineering, vol. 37, no. 11, pp. 2188-2199, Nov. 2009
14. M. Frijlink, L. Løvstakken, and H. Torp, Investigation of transmit and receive performance at the fundamental and third harmonic resonance frequency of a medical ultrasound transducer, Ultrasonics, vol. 49, no. 8, pp. 601-604, 2009
15. A. Swillens, L. Løvstakken, J. Kips, H. Torp, and P. Segers, Ultrasound Simulation of Complex Flow Velocity Fields Based on Computational Fluid Dynamics, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 56(3), pp. March 2009
16. N. Oddershede, L. Løvstakken, H. Torp, and J. A. Jensen, Estimating 2-D vector velocities using
    multi-dimensional spectrum analysis, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 55(8),  pp. 1744-1754, Aug. 2008
17. L. Løvstakken, S. Bjærum, and H. Torp, Optimal Velocity Estimation in Ultrasound Color Flow Imaging in Presence of Clutter, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 54(3), pp. 539-549, March 2007
18. L. Løvstakken, S. Bjærum, K. Kristoffersen, R. Haaverstad, and H. Torp, Real-time Adaptive Clutter Rejection Filtering in Ultrasound Color Flow Imaging Using Power Method Iterations. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 53(9),  pp. 1597-1608, Sept. 2006
19. L. Løvstakken, S. Bjærum, D. Martens, and H. Torp, Blood Flow Imaging - A New Real-Time 2D Flow Imaging Technique.  IEEE Transactions on ultrasonics, ferroelectrics, and frequency control, vol. 53(2), pp. 289-299, Feb. 2006

 [Clinical papers]

1. K. Van Canneyt, A. Swillens, L. Lovstakken, L. Antiga, P. Verdonck, and P. Segers, The accuracy of ultrasound volume flow measurements in the complex flow setting of a forearm vascular access, Journal of Vascular Access, Nov. 2012
2. H. Nordgaard, A. Swillens, D. Nordhaug, I. Kirkeby-Garstad, D. Van Loo, N. Vitale, P. Segers, R. Haaverstad, and L. Løvstakken, Impact of competitive flow on wall shear stress in coronary surgery: Computational fluid dynamics of a LIMA-LAD model, Cardiovascular Research, vol. 88(3), pp. 512-519, 2010
3. S. A. Nyrnes, L. Løvstakken, E. Skogvoll , H. Torp, B. O. Haugen, Does a new ultrasound flow modality improve visualization of neonatal pulmonary veins?, Echocardiography, vol. 27(9), pp. 1113-1119, 2010
4. O. Solheim, T. Selbekk, L. Løvstakken, G. A. Tangen, V. Solberg, J. Cappelen, G. Unsgaard, Intrasellar ultrasound in transsphenoidal surgery - a novel technique, Neurosurgery, vol. 66, no. 1, pp. 173-185, Jan. 2010
5. F. Lindseth and L. Løvstakken, O. Rygh, G. A. Tangen, H. Torp, and G. Undsgård, Blood Flow Imaging - An angle-independent ultrasound modality for intraoperative assessment of flow dynamics in neurovascular surgery, Neurosurgery, vol. 65, no. 6, pp. ons149-ons157, Dec. 2009
6. H. Nordgaard, D. Nordhaug, I. Kirkeby-Garstad, L. Løvstakken, N. Vitale, R. Haaverstad, Different graft flow patterns due to competitive flow or stenosis in the coronary anastomosis assessed by transit-time flowmetry in a porcine model, European Journal of Cardio-thoracic Surgery, vol. 36, no. 1, pp. 137-142, Jul. 2009
7. L. Løvstakken, K. S. Ibrahim, N. Vitale, S. T. Henriksen, I. Kirkeby-Garstad, H. Torp, and R. Haaverstad, Blood Flow Imaging - A new 2-D ultrasound modality for enhanced intraoperative visualization of blood flow patterns in coronary anastomoses, Journal of the American Society of Echocardiography, vol. 21(8), pp. 969-975, 2008
8. S. A. Nyrnes, L. Løvstakken, H. Torp, B. O. Haugen, Blood Flow Imaging - A New Angle Independent Ultrasound  Modality for the Visualization of Flow in Atrial Septal Defects in Children, Echocardiography, vol. 24(9), pp. 975-981, October 2007
9. K. S. Ibrahim, L. Løvstakken, I. Kirkeby-Garstad, H. Torp, H. Vik Mo, R. Haaverstad, Effect of the Cardiac Cycle on the Coronary Anastomosis Assessed by Ultrasound. Asian Cardiovascular and Thoracic Annals, vol. 15, pp. 86-90, April 2007

 [Conference proceeding papers]

1. L. Lovstakken, S. A. Nyrnes, B. O. haugen, and H. Torp, Angle-independent quantification of complex flow patterns in congenital heart disease, IEEE International Ultrasonics Symposium, Orlando, USA, 2011
2. D. Iversen, F. Lindseth, H. Torp, and L. Lovstakken, Model-based correction of angle-dependencies in navigated 3-D flow imaging during neurosurgical interventions, IEEE International Ultrasonics Symposium, Orlando, USA, 2011
3. S. Alnes, A. Swillens, P. Segers, H. Torp, and L. Lovstakken, Clutter filtering issues in speckle tracking for two-dimensional blood velocity estimation - a potential solution based on compounded imaging, IEEE International Ultrasonics Symposium, Orlando, USA, 2011
4. I. K. Ekroll, A. Swillens, P. Segers, H. Torp, and L. Lovstakken, Simultaneous quantification of flow and tissue velocities with an extended velocity range, IEEE International Ultrasonics Symposium, Orlando, USA, 2011
5. A. Swillens, G. De Santis, J. Degroote, L. Lovstakken, J. vierendeels, and P. Segers, Multiphysics modeling in support of ultrasonic image development: integration of fluid-structure interaction simulations and Field II applied to the carotid artery, IEEE International Ultrasonics Symposium, Orlando, USA, 2011
6. A. Swillens, G. De Santis, J. Degroote, L. Lovstakken, J. vierendeels, and P. Segers, Strain estimation in the carotid artery from ultrasonic wall tracking: a multiphysics model study, IEEE International Ultrasonics Symposium, Orlando, USA, 2011
7. L. Lovstakken and H. Torp, Extended Velocity Range in Color Flow Imaging using Parallel Receive Beamforming, IEEE International Ultrasonics Symposium, San Diego, USA, 2010
8. A. Swillens, P. Segers, H. Torp, and L. Lovstakken, Two-dimensional flow velocity estimation in the carotid bifurcation: a study of crossed-beam vector Doppler and speckle tracking using computational fluid dynamics, IEEE International Ultrasonics Symposium, Rome, Italy, 2009
9. L. Løvstakken, S.E. Måsøy, and A. Møllerløkken, Current Trends in Ultrasound Imaging Technology, SURF Imaging, and Decompression Induced Microbubbles, 77te Future of Diving: 100 Years of Haldane and Beyond, Smithsonian Institution, 2009
10. A. Swillens, L. Løvstakken, H. Torp, and P. Segers, A Comparison of Multidimensional Flow Estimation Techniques using Computational Fluid Dynamics: Speckle tracking versus Vector Doppler, IEEE International Ultrasonics Symposium, Beijing, China, 2008
11. M. Frijlink, L. Løvstakken, and H. Torp, Fundamental and Third Harmonic Operation of a Medical Phased Array Transducer, IEEE International Ultrasonics Symposium, Beijing, China, 2008
12. L. Løvstakken, F. Orderud, and H. Torp, Real-time Indication of Acoustic Window for Phased-Array Transducers in Ultrasound Imaging, IEEE International Ultrasonics Symposium, New York, 2007
13. L. Løvstakken, A. C. H. Yu, H. Torp, In Vivo Investigation of Filter Order Influence in Eigen-Based Clutter filtering for Color Flow Imaging, IEEE International Ultrasonics Symposium, New York, 2007
14. A. C. H. Yu and L. Løvstakken, Eigen-Based Clutter Filters for Color Flow Imaging: Single-Ensemble vs. Multi-Ensemble Approaches, IEEE International Ultrasonics Symposium, New York, 2007
15. N. Oddershede, L. Løvstakken, H. Torp, and J. A. Jensen, Multi-dimensional spectrum analysis for 2-D vector velocity estimation, IEEE International Ultrasonics Symposium, New York, 2007
16. L. Løvstakken, T. A. Tangen, S. Bjærum, and H. Torp, Optimal Velocity Estimation in Ultrasound Color Flow Imaging in Presence of Clutter Noise, IEEE International Ultrasonics Symposium, Vancouver, 2006
17. L. Løvstakken, S. Bjærum, D. Martens, H. Torp, Real-time Blood Motion Imaging - A 2D Flow Visualization Technique, IEEE International Ultrasonics Symposium, Montreal, 2004
18. L. Løvstakken, R. Haaverstad, P. Aadahl, S. Bjærum, S. Samstad, H. Torp, Quality Control of Off-Pump Coronary Heart Surgery using Ultrasound Color Flow Imaging with Adaptive Clutter Rejection Filters, IEEE International Ultrasonics Symposium, Hawaii, 2003

[Theses]

1. L. Løvstakken, Signal Processing in Diagnostic Ultrasound: Algorithms for Real-time Estimation and Visualization of Blood Flow Velocity, Doctoral Thesis 2007:25, Norwegian University of Science and Technology, 2007
2. L. Løvstakken, Estimation of Blood Flow Direction Using Ultrasound Speckle Tracking - A Real-time Implementation, Master Thesis, Norwegian University of Science and Technology, 2002