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  • 1.
    Ask, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Ressner, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Jansson, Tomas
    Lunds universitet .
    Jurkonis, Rytis
    Kaunas University of Technology, Lithuania .
    Kvikliene, Adriana
    Kaunas University of Technology, Lithuania .
    Hoff, Lars
    Fac of Sience and Engineering, Vestfold University, Horten, Norge .
    Simulation of ultrasound contrast bubble response and the non-linear ultrasound field - combining with in vitro experiments2003In: New England Doppler Conference,2003, 2003Conference paper (Refereed)
  • 2.
    Bernhardsson, Magnus
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Orthopaedics in Linköping.
    Sandberg, Olof
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Medical and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Orthopaedics in Linköping.
    Ressner, Marcus
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Medical radiation physics.
    Koziorowski, Jacek
    Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences.
    Malmqvist, Jonas
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Aspenberg, Per
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Orthopaedics in Linköping.
    Shining dead bone-cause for cautious interpretation of [F-18]NaF PET scans2018In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 89, no 1, p. 124-127Article in journal (Refereed)
    Abstract [en]

    Background and purpose — [18F]Fluoride ([18F]NaF) PET scan is frequently used for estimation of bone healing rate and extent in cases of bone allografting and fracture healing. Some authors claim that [18F]NaF uptake is a measure of osteoblastic activity, calcium metabolism, or bone turnover. Based on the known affinity of fluoride to hydroxyapatite, we challenged this view.

    Methods — 10 male rats received crushed, frozen allogeneic cortical bone fragments in a pouch in the abdominal wall on the right side, and hydroxyapatite granules on left side. [18F]NaF was injected intravenously after 7 days. 60 minutes later, the rats were killed and [18F]NaF uptake was visualized in a PET/CT scanner. Specimens were retrieved for micro CT and histology.

    Results — MicroCT and histology showed no signs of new bone at the implant sites. Still, the implants showed a very high [18F]NaF uptake, on a par with the most actively growing and remodeling sites around the knee joint.

    Interpretation — [18F]NaF binds with high affinity to dead bone and calcium phosphate materials. Hence, an [18F]NaF PET/CT scan does not allow for sound conclusions about new bone ingrowth into bone allograft, healing activity in long bone shaft fractures with necrotic fragments, or remodeling around calcium phosphate coated prostheses

  • 3.
    Eriksson Bylund, Nina
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Ressner, Marcus
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    3D Wiener filtering to reduce reverberations in ultrasound image sequences2003In: Image Analysis: 13th Scandinavian Conference, SCIA 2003 Halmstad, Sweden, June 29 – July 2, 2003 Proceedings / [ed] Josef Bigun and Tomas Gustavsson, Springer, 2003, Vol. 2749, p. 579-586Chapter in book (Refereed)
    Abstract [en]

    One of the most frequently occuring artifacts in ultrasound imaging is reverberations. These are multiple reflection echoes that result in ghost echoes in the ultrasound image. A method for reducing these unwanted artifacts using a three-dimensional (3D) Wiener filter is presented. The Wiener filter is a global filter and produces an estimate of the uncorrupted signal by minimizing the mean square error between the estimate and the uncorrupted signal in a statistical sense. The procedure works as follows: In a graphic interface the operator is displayed an image sequence. The operator marks two areas in one of the images, one area which contains a typical reverberation artifact, and one area free from artifact. Using these areas to produce noise and signal estimates, a Wiener filter is created and applied to the sequence. The 3D Wiener filters display excellent selection capabilities, and the developed method significantly reduces the magnitude of the reverberation artifact in the tested sequences.

  • 4.
    Eriksson-Bylund, Nina
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Ressner, Marcus
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Reverberation Reduction Using 3D Wiener Filtering2003Conference paper (Other academic)
    Abstract [en]

    One of the most common artifacts in ultrasound imaging is reverberations. These are multiple reflection echoes that register as coming from a deeper region than the depth of the interface that are causing them, and result in ghost echoes in the ultrasound image. A method to reduce these unwanted artifacts using a three dimensional (2D + time) Wiener filter has been developed. Two sequences of iq-data, the least processed signal possible to retrieve from the ultrasound system (Vingmed System Five), have been used to test the method: One sequence on a tissue-mimicking agar gel phantom in which bars of glass simulating ribs give rise to reverberations, and one sequence on an open-chest pig with a strong reverberation from a water-filled rubber glove used as a medium between the heart and the transducer. The procedure works as follows: In a graphic interface the operator is shown the image sequence. In one of the frames two areas must be marked out; One area which contains a typical reverberation artifact, and one area which will represent an artifact free signal. After creating the three dimensional Wiener filter post-processing of the sequence is performed. The developed method significantly reduced the magnitude of the reverberation artifact in the tested sequences.

  • 5.
    Kvikliene, Adriana
    et al.
    Institute of Biomedical Engineering, Kaunas University of Technology, K. Donelaicio st. 73, Kaunas LT-3006, Lithuania.
    Jurkonis, Rytis
    Institute of Biomedical Engineering, Kaunas University of Technology, K. Donelaicio st. 73, Kaunas LT-3006, Lithuania.
    Ressner, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Hoff, Lars
    Faculty of Science and Engineering, Vestfold University College, P.O. Box 2243, N-3103 Tønsberg, Norway.
    Jansson, Tomas
    Department of Electrical Measurements, Lund University, P.O. Box 118, SE-221 00, Lund, Sweden.
    Janerot Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Lukosevicius, Arunas
    Institute of Biomedical Engineering, Kaunas University of Technology, K. Donelaicio st. 73, Kaunas LT-3006, Lithuania.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Modelling of nonlinear effects and the response of ultrasound contrast micro bubbles: simulation and experiment2004In: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 42, no 01-Sep, p. 301-307Article in journal (Refereed)
    Abstract [en]

    The propagation of diagnostic ultrasonic imaging pulses in tissue and their interaction with contrast micro bubbles is a very complex physical process, which we assumed to be separable into three stages: pulse propagation in tissue, the interaction of the pulse with the contrast bubble, and the propagation of the scattered echo. The model driven approach is used to gain better knowledge of the complex processes involved. A simplified way of field simulation is chosen due to the complexity of the task and the necessity to estimate comparative contributions of each component of the process. Simulations are targeted at myocardial perfusion estimation. A modified method for spatial superposition of attenuated waves enables simulations of low intensity pulse pressure fields from weakly focused transducers in a nonlinear, attenuating, and liquid-like biological medium. These assumptions enable the use of quasi-linear calculations of the acoustic field. The simulations of acoustic bubble response are carried out with the Rayleigh-Plesset equation with the addition of radiation damping. Theoretical simulations with synthesised and experimentally sampled pulses show that the interaction of the excitation pulses with the contrast bubbles is the main cause of nonlinear scattering, and a 2-3 dB increase of second harmonic amplitude depends on nonlinear distortions of the incident pulse. (C) 2004 Elsevier B.V. All rights reserved.

  • 6.
    Norén, Bengt
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Medical Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology UHL.
    Lundberg, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ressner, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Wirell, Staffan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Medical Radiology.
    Almer, Sven
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Gastroenterology and Hepatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Endocrinology and Gastroenterology UHL.
    Smedby, Örjan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Medical Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology UHL. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Absolute quantification of human liver metabolite concentrations by localized in vivo 31P NMR spectroscopy in diffuse liver disease2005In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 15, no 1, p. 148-157Article in journal (Refereed)
    Abstract [en]

    Phosphorus-31 NMR spectroscopy using slice selection (DRESS) was used to investigate the absolute concentrations of metabolites in the human liver. Absolute concentrations provide more specific biochemical information compared to spectrum integral ratios. Nine patients with histopathologically proven diffuse liver disease and 12 healthy individuals were examined in a 1.5-T MR scanner (GE Signa LX Echospeed plus). The metabolite concentration quantification procedures included: (1) determination of optimal depth for the in vivo measurements, (2) mapping the detection coil characteristics, (3) calculation of selected slice and liver volume ratios using simple segmentation procedures and (4) spectral analysis in the time domain. The patients had significantly lower concentrations of phosphodiesters (PDE), 6.3±3.9 mM, and ATP-β, 3.6±1.1 mM, (P<0.05) compared with the control group (10.0±4.2 mM and 4.2±0.3 mM, respectively). The concentrations of phosphomonoesters (PME) were higher in the patient group, although this was not significant. Constructing an anabolic charge (AC) based on absolute concentrations, [PME]/([PME] + [PDE]), the patients had a significantly larger AC than the control subjects, 0.29 vs. 0.16 (P<0.005). Absolute concentration measurements of phosphorus metabolites in the liver are feasible using a slice selective sequence, and the technique demonstrates significant differences between patients and healthy subjects.

  • 7.
    Norén, Bengt
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology UHL.
    Smedby, Örjan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology UHL. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Ressner, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Lundberg, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Quantification of liver metabolites with phosphorus-31 Magnetic Resonance Spectroscopy2002In: European Congress of Radiology March 1-5, 2002,2002, 2002, p. 353-353Conference paper (Refereed)
  • 8.
    Ressner, Marcus
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    On Nonlinear Acoustics in Contrast Echocardiography2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ultrasound is one of the most commonly used noninvasive medical imaging techniques. Ultrasound contrast agents (UCA), consisting of encapsulated gas-filled microbubbles, have shown to increase the diagnostic precision in selected low echogenic patients. UCA also holds promise for bedside evaluation of myocardial perfusion quantification, but is not yet reproducible and specific enough for clinical use. In addition risks have been addressed when used, as first recommended, together with high mechanical index (MI) for reperfusion assessment by contrast destruction. We clinically observed increased myocardial velocities after UCA-administration when applied simultaneously with color tissue Doppler imaging (CTDI) arising the question if this increase was due to physiological factors or physical changes in the backscattered signals when UCA were present.

    The aims of the thesis was to explain this velocity shift and simultaneously to contribute to a future safe and contrast specific application by further characterizing the non-linear acoustic properties of UCA when located in an acoustic field. Of specific interest was to evaluate in which way nonlinear wave propagation affects the response from UCA and if a change in pulse shape, length or polarity can be utilized to increase the nonlinear signal contribution.

    Twelve patients with ischemic heart disease were examined with CTDI before and after UCA-administration in order to verify the change in peak systolic velocity. An experimental in vitro model including flow and tissue phantoms for UCA was established for CTDI. Raw data from single-element transducers and clinical ultrasound systems were collected for three different UCA and analyzed to determine if the observed velocity shift could be reproduced in vitro and to find a possible cause. Our results show in vivo and in vitro that UCA will affect the autocorrelation phase shift estimator used for CTDI in terms of contribution from rupturing UCA microbubbles, which explains the velocity shift. CTDI during contrast infusion should therefore be avoided unless it can be performed at low MI where the majority of the UCA are intact.

    The computational model for spatial superposition of attenuated waves was modified to include an operator for pulse distortion from nonlinear wave propagation. The Matlab™ toolbox Bubblesim based on a modified Rayleigh-Plesset-equation and with insonation parameters such as frequency, pressure amplitude, pulse length and polarity was used to study the response from single microbubbles either for simulated pulses or for pulses generated by clinical ultrasound systems and single element transducers. The combination of the two models also provided a computational platform to asses pulse distortion from nonlinear wave propagation, the response of the UCA bubble and the linear backscatter of the low amplitude bubble echo. When evaluating the harmonic response in simulations and in vitro, the interaction of the excitation pulses with the contrast bubbles was identified as the main cause of nonlinear scattering, and a 2-3 dB increase of the second harmonic amplitude depends on nonlinear distortions of the incident pulse. By applying small changes of short (<3.5 cycles) and fragmented transmitted wideband pulses of 2-2.5 MHz, it is shown that inverted pulse polarity considerably modulates power without affecting a low and safe MI (<0.4), and the results lodged promise to further to enhance a contrast response.

    List of papers
    1. Effects of ultrasound contrast agents on doppler tissue velocity estimation
    Open this publication in new window or tab >>Effects of ultrasound contrast agents on doppler tissue velocity estimation
    Show others...
    2006 (English)In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 19, no 2, p. 154-164Article in journal (Refereed) Published
    Abstract [en]

    The combination of Doppler tissue imaging and myocardial contrast echocardiography has the potential to provide information about motion and perfusion of the myocardium in a single examination. The purpose of this study was to establish how the presence of ultrasound contrast agent (UCA) affects measurements of Doppler tissue velocities in vivo and in vitro. We performed echocardiography in 12 patients with ischemic heart disease before and immediately after a slow intravenous infusion of the UCA Optison, using color Doppler tissue imaging to examine the effect of contrast agents in vivo. The myocardial peak systolic velocities and their integrals were analyzed in digitally stored cineloops before and after contrast administration. To distinguish between methodologic and physiologic factors affecting the measurement of tissue velocity in vitro, experiments with a rotating disk and a flow cone phantom were also carried out for the 3 contrast agents: Optison, Sonovue, and Sonazoid. In vivo results show that the values for peak systolic velocity increased by about 10% during contrast infusion, from mean 5.2 ± 1.8 to 5.7 ± 2.3 cm/s (P = .02, 95% confidence interval 2%-16%). The increase in myocardial peak systolic velocities was verified in experimental models in which the UCA increased the estimated mean velocity in the order of 5% to 20% for the motion interval of 5 to 7 cm/s, corresponding to the myocardial velocities studied in vivo. The response was similar for all 3 contrast agents and was not affected by moderate variations in concentration of the agent. We have shown that the presence UCA will affect Doppler tissue measurements in vivo and in vitro. The observed bias is presumed to be an effect of harmonic signal contribution from rupturing contrast agent microbubbles and does not indicate biologic or physiologic effects. Copyright 2006 by the American Society of Echocardiography.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-28716 (URN)10.1016/j.echo.2005.09.025 (DOI)13885 (Local ID)13885 (Archive number)13885 (OAI)
    Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
    2. Contrast Biases the Autocorrelation Phase Shift Estimation in Doppler Tissue Imaging
    Open this publication in new window or tab >>Contrast Biases the Autocorrelation Phase Shift Estimation in Doppler Tissue Imaging
    Show others...
    2009 (English)In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 35, no 3, p. 447-457Article in journal (Refereed) Published
    Abstract [en]

    Quantitative assessment of regional myocardial function at rest and during stress with Doppler tissue imaging (DTI) plays an important role in daily routine echocardiography. However, reliable visual analysis is largely dependent on image quality and adequate border delineation, which still remains a challenge in a significant number of patients. In this respect, an ultrasound contrast agent (UCA) is often used to improve visualization in patients with suboptimal image quality. The knowledge of how DTI measurements will be affected by UCA present in the tissue is therefore of significant importance for an accurate interpretation of local myocardial motion. The aim of this paper was to investigate how signal contribution from UCA and nonlinear wave propagation influence the performance of the autocorrelation phase shift estimator used for DTI applications. Our results are based on model experiments with a clinical 2-D grayscale scanner and computational simulations or the DTI velocity estimator for synthetically-derived pulses, simulated bubble echoes and experimentally-sampled RF data of transmitted pulses and backscattered contrast echoes. The results show that destruction of UCA present in the tissue will give rise to an apparent bidirectional velocity bias of individual velocity estimates, but that spatial averaging of individual velocity measurements within a region-of-interest will result in a negative bias (away from the transducer) of the estimated mean or mean peak velocity. The UCA destruction will also have a significant impact on the measured integrated mean velocity over time, i.e., displacement. To achieve improved visualization with UCA during DTI-examinations, we either recommend that it is performed at low acoustic powers, mechanical index <= 0.3, thereby minimizing the effects from bubble rupture, or that each Doppler pulse package is preceded by a destruction burst similar to "Flash imaging" to clear the target area of contrast microbubbles.

    Keywords
    Ultrasound, Tissue Doppler, Contrast, Microbubbles, Velocity estimation
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-17277 (URN)10.1016/j.ultrasmedbio.2008.09.012 (DOI)
    Available from: 2009-03-16 Created: 2009-03-16 Last updated: 2017-12-13
    3. Modelling of nonlinear effects and the response of ultrasound contrast micro bubbles: simulation and experiment
    Open this publication in new window or tab >>Modelling of nonlinear effects and the response of ultrasound contrast micro bubbles: simulation and experiment
    Show others...
    2004 (English)In: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 42, no 01-Sep, p. 301-307Article in journal (Refereed) Published
    Abstract [en]

    The propagation of diagnostic ultrasonic imaging pulses in tissue and their interaction with contrast micro bubbles is a very complex physical process, which we assumed to be separable into three stages: pulse propagation in tissue, the interaction of the pulse with the contrast bubble, and the propagation of the scattered echo. The model driven approach is used to gain better knowledge of the complex processes involved. A simplified way of field simulation is chosen due to the complexity of the task and the necessity to estimate comparative contributions of each component of the process. Simulations are targeted at myocardial perfusion estimation. A modified method for spatial superposition of attenuated waves enables simulations of low intensity pulse pressure fields from weakly focused transducers in a nonlinear, attenuating, and liquid-like biological medium. These assumptions enable the use of quasi-linear calculations of the acoustic field. The simulations of acoustic bubble response are carried out with the Rayleigh-Plesset equation with the addition of radiation damping. Theoretical simulations with synthesised and experimentally sampled pulses show that the interaction of the excitation pulses with the contrast bubbles is the main cause of nonlinear scattering, and a 2-3 dB increase of second harmonic amplitude depends on nonlinear distortions of the incident pulse. (C) 2004 Elsevier B.V. All rights reserved.

    Keywords
    ultrasound, simulation, nonlinear, contrast agents
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-46245 (URN)10.1016/j.ultras.2004.01.023 (DOI)
    Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
    4. Ultrasound contrast response to variation of incident pulse length and polarity
    Open this publication in new window or tab >>Ultrasound contrast response to variation of incident pulse length and polarity
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Microbubbles are used as ultrasound contrast agents (UCA) in diagnostic ultrasound as they considerably enhance the backscattered signal and generate specific signal characteristics that can be used to isolate echoes that originate from the blood volume. Emerging new advanced contrast specific insonation techniques have shown to better discriminate the backscattered UCA-signal but has not gained clinical practice due to their complexity and the need for additional soft- and hardware, or due to the debated safety aspects regarding microbubble cavitation at mechanical index (MI >>0.4). In this study we investigate a simplified approach to improve the nonlinear signal contribution from UCA at low MI < 0.4 by utilizing the asymmetry between positive and negative peak pressures for pulse lengths ≤3.5 cycles. In vitro registrations of the transmitted pulse peak pressure asymmetry from a single element transducer were obtained with a needle hydrophone after a transducer excitation pulse with increasing length from 0.5 to 5 cycles. A computational model (Bubblesim) was used to investigate the response from a single microbubble after interaction with transmitted pulse with variations of length, shape and polarity. Our results show that small changes (quarters of a pulse cycle) will change the transmitted pulse shape and distribution of peak pressures and that this effect can be used to change the scattering behavior of UCA in simulations and in vitro. This effect will increase with decreasing pulse lengths <5 cycles. The best case scenario for differentiation of harmonic UCA response with polarity change at MI <0.4 and real time imaging can for transducer frequencies of 2-2.5 MHz be found for pulse lengths of 2.25 and 2.75 cycles in the acoustic pressure interval of 300-500 kPa.

    Keywords
    Ultrasound contrast agents, nonlinear imaging, harmonic imaging, contrast echocardiography
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-65417 (URN)
    Available from: 2011-02-07 Created: 2011-02-07 Last updated: 2011-02-07
  • 9.
    Ressner, Marcus
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Brodin, Lars-Åke
    The Royal Institute of Technology, Stockholm, Sweden.
    Jansson, Tomas
    Lund Institute of Technology, Lund, Sweden.
    Hoff, Lars
    Vestfold University College, Noway.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Effects of ultrasound contrast agents on doppler tissue velocity estimation2006In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 19, no 2, p. 154-164Article in journal (Refereed)
    Abstract [en]

    The combination of Doppler tissue imaging and myocardial contrast echocardiography has the potential to provide information about motion and perfusion of the myocardium in a single examination. The purpose of this study was to establish how the presence of ultrasound contrast agent (UCA) affects measurements of Doppler tissue velocities in vivo and in vitro. We performed echocardiography in 12 patients with ischemic heart disease before and immediately after a slow intravenous infusion of the UCA Optison, using color Doppler tissue imaging to examine the effect of contrast agents in vivo. The myocardial peak systolic velocities and their integrals were analyzed in digitally stored cineloops before and after contrast administration. To distinguish between methodologic and physiologic factors affecting the measurement of tissue velocity in vitro, experiments with a rotating disk and a flow cone phantom were also carried out for the 3 contrast agents: Optison, Sonovue, and Sonazoid. In vivo results show that the values for peak systolic velocity increased by about 10% during contrast infusion, from mean 5.2 ± 1.8 to 5.7 ± 2.3 cm/s (P = .02, 95% confidence interval 2%-16%). The increase in myocardial peak systolic velocities was verified in experimental models in which the UCA increased the estimated mean velocity in the order of 5% to 20% for the motion interval of 5 to 7 cm/s, corresponding to the myocardial velocities studied in vivo. The response was similar for all 3 contrast agents and was not affected by moderate variations in concentration of the agent. We have shown that the presence UCA will affect Doppler tissue measurements in vivo and in vitro. The observed bias is presumed to be an effect of harmonic signal contribution from rupturing contrast agent microbubbles and does not indicate biologic or physiologic effects. Copyright 2006 by the American Society of Echocardiography.

  • 10.
    Ressner, Marcus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Brodin, Lars-Åke
    Jansson, Tomas
    Dept of Electrical Measurements Lund University.
    Hoff, Lars
    Faculty of Science and Engineering Vestfold University, Horten, Norge.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Effekter av ultraljudskontrast vid hastighetsestimering med vävnadsdoppler2005In: Svenska Läkaresällskapets Riksstämma 2005,2005, 2005Conference paper (Other academic)
  • 11.
    Ressner, Marcus
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Brodin, L-Å.
    Jansson, Tomas
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Janerot-Sjöberg, Birgitta
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    How Ultrasound Contrast Agents effects Doppler Tissue Velocity Estimation2006Conference paper (Other academic)
  • 12.
    Ressner, Marcus
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Gustafsson, Disa
    Karolinska Institutet, Stockholm.
    Gustafsson, Agnetha
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Jonsson, Cathrine
    Karolinska universitetssjukhuset Solna, Stockholm.
    Experimental evaluation of iterative reconstruction for whole-body F-18 PET in a 3- and 4-ring PET/CT system2011Conference paper (Other academic)
  • 13.
    Ressner, Marcus
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Jansson, Tomas
    Lund University.
    Cedefamn, Jonny
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Janerot Sjöberg, Birgitta
    Linköping University, Department of Medicine and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Contrast Biases the Autocorrelation Phase Shift Estimation in Doppler Tissue Imaging2009In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 35, no 3, p. 447-457Article in journal (Refereed)
    Abstract [en]

    Quantitative assessment of regional myocardial function at rest and during stress with Doppler tissue imaging (DTI) plays an important role in daily routine echocardiography. However, reliable visual analysis is largely dependent on image quality and adequate border delineation, which still remains a challenge in a significant number of patients. In this respect, an ultrasound contrast agent (UCA) is often used to improve visualization in patients with suboptimal image quality. The knowledge of how DTI measurements will be affected by UCA present in the tissue is therefore of significant importance for an accurate interpretation of local myocardial motion. The aim of this paper was to investigate how signal contribution from UCA and nonlinear wave propagation influence the performance of the autocorrelation phase shift estimator used for DTI applications. Our results are based on model experiments with a clinical 2-D grayscale scanner and computational simulations or the DTI velocity estimator for synthetically-derived pulses, simulated bubble echoes and experimentally-sampled RF data of transmitted pulses and backscattered contrast echoes. The results show that destruction of UCA present in the tissue will give rise to an apparent bidirectional velocity bias of individual velocity estimates, but that spatial averaging of individual velocity measurements within a region-of-interest will result in a negative bias (away from the transducer) of the estimated mean or mean peak velocity. The UCA destruction will also have a significant impact on the measured integrated mean velocity over time, i.e., displacement. To achieve improved visualization with UCA during DTI-examinations, we either recommend that it is performed at low acoustic powers, mechanical index <= 0.3, thereby minimizing the effects from bubble rupture, or that each Doppler pulse package is preceded by a destruction burst similar to "Flash imaging" to clear the target area of contrast microbubbles.

  • 14.
    Ressner, Marcus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Kvikliene, Adriana
    Kaunas University of Technology.
    Hoff, Lars
    Westfold University College.
    Jurkonis, Rytis
    Kaunas University of Technology.
    Jansson, Tomas
    Lunds universitet.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Lukosevicius, Arunas
    Kaunas University of Technology.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Backscattered ultrasound from contrast microbubbles: effects of tissue and bubble interaction2004In: EMBS,2004, San Francisco: IEEE , 2004, p. 849-Conference paper (Refereed)
  • 15.
    Ressner, Marcus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Kvikliene, Adriana
    Inst of Biomedical Engineering Kaunas University of Technology,Lithuania.
    Hoff, Lars
    Faculty ofScience and Engineering Vestfold University, Horten, Norge.
    Jurkonis, Rytis
    Inst of Biomedical Engineering Kaunas University of Technology, Lithuania.
    Jansson, Tomas
    Dept of Electrical Measurements Lunds universitet.
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Lukosevicius, Arunas
    Inst of Biomedical Engineering Kaunas University of Technology, Lithuania.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Ultrasound contrast for perfusion studies2005In: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005, Umeå: IFMBE , 2005, p. 107-Conference paper (Refereed)
  • 16.
    Ressner, Marcus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Kvikliene, Adriana
    Kaunas University of Technology .
    Hoff, Lars
    Vestfold University, Horten Norge.
    Jurkonis, Rytis
    Kaunas University of Technology .
    Jansson, Tomas
    Lund University .
    Janerot-Sjöberg, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    Lukosevicius, Arunas
    Kaunas University of Technology .
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Ultrasound contrast microbubbles: simulations and in vitro experiments2005In: EMBEC05,2005, Prag: IFMBE , 2005Conference paper (Refereed)
  • 17.
    Ressner, Marcus
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Kviklienė, Adriana
    Institute of Biomedical Engineering, Kaunas University of Technology, Kaunas LT-3006, Lithuania.
    Jansson, Tomas
    Department of Electrical Measurements, Lund University, SE-22100 Lund, Sweden.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Janerot‐Sjoberg, Birgitta
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Ultrasound contrast response to variation of incident pulse length and polarityManuscript (preprint) (Other academic)
    Abstract [en]

    Microbubbles are used as ultrasound contrast agents (UCA) in diagnostic ultrasound as they considerably enhance the backscattered signal and generate specific signal characteristics that can be used to isolate echoes that originate from the blood volume. Emerging new advanced contrast specific insonation techniques have shown to better discriminate the backscattered UCA-signal but has not gained clinical practice due to their complexity and the need for additional soft- and hardware, or due to the debated safety aspects regarding microbubble cavitation at mechanical index (MI >>0.4). In this study we investigate a simplified approach to improve the nonlinear signal contribution from UCA at low MI < 0.4 by utilizing the asymmetry between positive and negative peak pressures for pulse lengths ≤3.5 cycles. In vitro registrations of the transmitted pulse peak pressure asymmetry from a single element transducer were obtained with a needle hydrophone after a transducer excitation pulse with increasing length from 0.5 to 5 cycles. A computational model (Bubblesim) was used to investigate the response from a single microbubble after interaction with transmitted pulse with variations of length, shape and polarity. Our results show that small changes (quarters of a pulse cycle) will change the transmitted pulse shape and distribution of peak pressures and that this effect can be used to change the scattering behavior of UCA in simulations and in vitro. This effect will increase with decreasing pulse lengths <5 cycles. The best case scenario for differentiation of harmonic UCA response with polarity change at MI <0.4 and real time imaging can for transducer frequencies of 2-2.5 MHz be found for pulse lengths of 2.25 and 2.75 cycles in the acoustic pressure interval of 300-500 kPa.

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