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Ressner, Marcus
Publications (10 of 16) Show all publications
Ressner, M., Gustafsson, D., Gustafsson, A. & Jonsson, C. (2011). Experimental evaluation of iterative reconstruction for whole-body F-18 PET in a 3- and 4-ring PET/CT system. Paper presented at EANM'11, 15-19 October 2011, Birmingham, UK.
Open this publication in new window or tab >>Experimental evaluation of iterative reconstruction for whole-body F-18 PET in a 3- and 4-ring PET/CT system
2011 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Medical Image Processing
Identifiers
urn:nbn:se:liu:diva-79371 (URN)
Conference
EANM'11, 15-19 October 2011, Birmingham, UK
Available from: 2012-07-16 Created: 2012-07-16 Last updated: 2012-08-14
Ressner, M. (2010). On Nonlinear Acoustics in Contrast Echocardiography. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>On Nonlinear Acoustics in Contrast Echocardiography
2010 (English)Doctoral 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.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. p. 114
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1338
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-65418 (URN)978-91-7393-315-5 (ISBN)
Public defence
2010-11-12, Eken, Campus US, Linköpings universitet, Linököping, 09:15 (Swedish)
Opponent
Supervisors
Available from: 2011-02-07 Created: 2011-02-07 Last updated: 2011-02-07Bibliographically approved
Ressner, M., Jansson, T., Cedefamn, J., Ask, P. & Janerot Sjöberg, B. (2009). Contrast Biases the Autocorrelation Phase Shift Estimation in Doppler Tissue Imaging. Ultrasound in Medicine and Biology, 35(3), 447-457
Open this publication in new window or tab >>Contrast Biases the Autocorrelation Phase Shift Estimation in Doppler Tissue Imaging
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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
Ressner, M., Brodin, L.-Å., Jansson, T., Hoff, L., Ask, P. & Janerot-Sjöberg, B. (2006). Effects of ultrasound contrast agents on doppler tissue velocity estimation. Journal of the American Society of Echocardiography, 19(2), 154-164
Open this publication in new window or tab >>Effects of ultrasound contrast agents on doppler tissue velocity estimation
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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
Ressner, M., Brodin, L.-Å., Jansson, T., Ask, P. & Janerot-Sjöberg, B. (2006). How Ultrasound Contrast Agents effects Doppler Tissue Velocity Estimation. Paper presented at World Conference on Medical Physics and Biological Engineering, Seoul.
Open this publication in new window or tab >>How Ultrasound Contrast Agents effects Doppler Tissue Velocity Estimation
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2006 (English)Conference paper, Published paper (Other academic)
National Category
Medical and Health Sciences Biomedical Laboratory Science/Technology
Identifiers
urn:nbn:se:liu:diva-56397 (URN)
Conference
World Conference on Medical Physics and Biological Engineering, Seoul
Available from: 2010-05-10 Created: 2010-05-10 Last updated: 2010-06-14
Norén, B., Lundberg, P., Ressner, M., Wirell, S., Almer, S. & Smedby, Ö. (2005). Absolute quantification of human liver metabolite concentrations by localized in vivo 31P NMR spectroscopy in diffuse liver disease. European Radiology, 15(1), 148-157
Open this publication in new window or tab >>Absolute quantification of human liver metabolite concentrations by localized in vivo 31P NMR spectroscopy in diffuse liver disease
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2005 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 15, no 1, p. 148-157Article in journal (Refereed) Published
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.

Keywords
phosphorus MR spectroscopy, absolute concentrations, diffuse liver disease
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24421 (URN)10.1007/s00330-004-2434-x (DOI)000227354900022 ()6524 (Local ID)6524 (Archive number)6524 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
Ressner, M., Brodin, L.-Å., Jansson, T., Hoff, L., Ask, P. & Janerot-Sjöberg, B. (2005). Effekter av ultraljudskontrast vid hastighetsestimering med vävnadsdoppler. In: Svenska Läkaresällskapets Riksstämma 2005,2005.
Open this publication in new window or tab >>Effekter av ultraljudskontrast vid hastighetsestimering med vävnadsdoppler
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2005 (Swedish)In: Svenska Läkaresällskapets Riksstämma 2005,2005, 2005Conference paper, Published paper (Other academic)
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-30519 (URN)16099 (Local ID)16099 (Archive number)16099 (OAI)
Available from: 2009-10-09 Created: 2009-10-09
Ressner, M., Kvikliene, A., Hoff, L., Jurkonis, R., Jansson, T., Janerot-Sjöberg, B., . . . Ask, P. (2005). Ultrasound contrast for perfusion studies. In: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005 (pp. 107). Umeå: IFMBE
Open this publication in new window or tab >>Ultrasound contrast for perfusion studies
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2005 (English)In: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005, Umeå: IFMBE , 2005, p. 107-Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Umeå: IFMBE, 2005
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-28763 (URN)13940 (Local ID)13940 (Archive number)13940 (OAI)
Available from: 2009-10-09 Created: 2009-10-09
Ressner, M., Kvikliene, A., Hoff, L., Jurkonis, R., Jansson, T., Janerot-Sjöberg, B., . . . Ask, P. (2005). Ultrasound contrast microbubbles: simulations and in vitro experiments. In: EMBEC05,2005. Prag: IFMBE
Open this publication in new window or tab >>Ultrasound contrast microbubbles: simulations and in vitro experiments
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2005 (English)In: EMBEC05,2005, Prag: IFMBE , 2005Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Prag: IFMBE, 2005
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-30198 (URN)15692 (Local ID)15692 (Archive number)15692 (OAI)
Available from: 2009-10-09 Created: 2009-10-09
Ressner, M., Kvikliene, A., Hoff, L., Jurkonis, R., Jansson, T., Janerot-Sjöberg, B., . . . Ask, P. (2004). Backscattered ultrasound from contrast microbubbles: effects of tissue and bubble interaction. In: EMBS,2004 (pp. 849). San Francisco: IEEE
Open this publication in new window or tab >>Backscattered ultrasound from contrast microbubbles: effects of tissue and bubble interaction
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2004 (English)In: EMBS,2004, San Francisco: IEEE , 2004, p. 849-Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
San Francisco: IEEE, 2004
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24371 (URN)6463 (Local ID)6463 (Archive number)6463 (OAI)
Available from: 2009-10-07 Created: 2009-10-07
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