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Janerot-Sjöberg, BirgittaORCID iD iconorcid.org/0000-0003-1264-1254
Alternative names
Publications (10 of 28) Show all publications
Fröberg, A., Mårtensson, M., Larsson, M., Janerot-Sjöberg, B., D'Hooge, J. & Arndt, A. (2016). High variability in strain estimation errors when using a commercial ultrasound speckle tracking algorithm on tendon tissue. Acta Radiologica, 57(10), 1223-1229
Open this publication in new window or tab >>High variability in strain estimation errors when using a commercial ultrasound speckle tracking algorithm on tendon tissue
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2016 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 57, no 10, p. 1223-1229Article in journal (Refereed) Published
Abstract [en]

Background: Ultrasound speckle tracking offers a non-invasive way of studying strain in the free Achilles tendon where no anatomical landmarks are available for tracking. This provides new possibilities for studying injury mechanisms during sport activity and the effects of shoes, orthotic devices, and rehabilitation protocols on tendon biomechanics. Purpose: To investigate the feasibility of using a commercial ultrasound speckle tracking algorithm for assessing strain in tendon tissue. Material and Methods: A polyvinyl alcohol (PVA) phantom, three porcine tendons, and a human Achilles tendon were mounted in a materials testing machine and loaded to 4% peak strain. Ultrasound long-axis cine-loops of the samples were recorded. Speckle tracking analysis of axial strain was performed using a commercial speckle tracking software. Estimated strain was then compared to reference strain known from the materials testing machine. Two frame rates and two region of interest (ROI) sizes were evaluated. Results: Best agreement between estimated strain and reference strain was found in the PVA phantom (absolute error in peak strain: 0.21 +/- 0.08%). The absolute error in peak strain varied between 0.72 +/- 0.65% and 10.64 +/- 3.40% in the different tendon samples. Strain determined with a frame rate of 39.4Hz had lower errors than 78.6Hz as was the case with a 22mm compared to an 11mm ROI. Conclusion: Errors in peak strain estimation showed high variability between tendon samples and were large in relation to strain levels previously described in the Achilles tendon.

Place, publisher, year, edition, pages
Sage Publications, 2016
Keywords
Speckle tracking, strain, Achilles tendon, ultrasound
National Category
Medical Equipment Engineering Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:kth:diva-193792 (URN)10.1177/0284185115626471 (DOI)000382967500013 ()26787677 (PubMedID)2-s2.0-84987786849 (Scopus ID)
Funder
Stockholm County CouncilSwedish National Centre for Research in Sports
Note

QC 20161024

Available from: 2016-10-24 Created: 2016-10-11 Last updated: 2017-11-29Bibliographically approved
Gharehbaghi, A., Ask, P., Nylander, E., Janerot-Sjoberg, B., Ekman, I., Lindén, M. & Babic, A. (2015). A hybrid model for diagnosing sever aortic stenosis in asymptomatic patients using phonocardiogram. In: IFMBE Proceedings: . Paper presented at World Congress on Medical Physics and Biomedical Engineering, 2015, 7 June 2015 through 12 June 2015 (pp. 1006-1009). Springer
Open this publication in new window or tab >>A hybrid model for diagnosing sever aortic stenosis in asymptomatic patients using phonocardiogram
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2015 (English)In: IFMBE Proceedings, Springer, 2015, p. 1006-1009Conference paper, Published paper (Refereed)
Abstract [en]

This study presents a screening algorithm for severe aortic stenosis (AS), based on a processing method for phonocardiographic (PCG) signal. The processing method employs a hybrid model, constituted of a hidden Markov model and support vector machine. The method benefits from a preprocessing phase for an enhanced learning. The performance of the method is statistically evaluated using PCG signals recorded from 50 individuals who were referred to the echocardiography lab at Linköping University hospital. All the individuals were diagnosed as having a degree of AS, from mild to severe, according to the echocardiographic measurements. The patient group consists of 26 individuals with severe AS, and the rest of the 24 patients comprise the control group. Performance of the method is statistically evaluated using repeated random sub sampling. Results showed a 95% confidence interval of (80.5%-82.8%) /(77.8%- 80.8%) for the accuracy/sensitivity, exhibiting an acceptable performance to be used as decision support system in the primary healthcare center.

Place, publisher, year, edition, pages
Springer, 2015
Keywords
Aortic stenosis, Decision support, Hybrid model, Phonocardiogram, Primary healthcare centers, Algorithms, Artificial intelligence, Biomedical engineering, Blood vessels, Decision support systems, Diseases, Echocardiography, Health care, Hidden Markov models, Markov processes, Phonocardiography, Processing, Decision supports, Phonocardiograms, Primary healthcare, Diagnosis
National Category
Biomedical Laboratory Science/Technology
Identifiers
urn:nbn:se:kth:diva-181542 (URN)10.1007/978-3-319-19387-8_245 (DOI)000381813000245 ()2-s2.0-84944326372 (Scopus ID)9783319193878 (ISBN)
Conference
World Congress on Medical Physics and Biomedical Engineering, 2015, 7 June 2015 through 12 June 2015
Note

QC 20160229

Available from: 2016-02-29 Created: 2016-02-02 Last updated: 2016-09-30Bibliographically approved
Gharehbaghi, A., Borga, M., Janerot Sjöberg, B. & Ask, P. (2015). A novel method for discrimination between innocent and pathological heart murmurs. Medical Engineering and Physics, 37(7), 674-682
Open this publication in new window or tab >>A novel method for discrimination between innocent and pathological heart murmurs
2015 (English)In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 37, no 7, p. 674-682Article in journal (Refereed) Published
Abstract [en]

This paper presents a novel method for discrimination between innocent and pathological murmurs using the growing time support vector machine (GTSVM). The proposed method is tailored for characterizing innocent murmurs (IM) by putting more emphasis on the early parts of the signal as IMs are often heard in early systolic phase. Individuals with mild to severe aortic stenosis (AS) and IM are the two groups subjected to analysis, taking the normal individuals with no murmur (NM) as the control group. The AS is selected due to the similarity of its murmur to IM, particularly in mild cases. To investigate the effect of the growing time windows, the performance of the GTSVM is compared to that of a conventional support vector machine (SVM), using repeated random sub-sampling method. The mean value of the classification rate/sensitivity is found to be 88%/86% for the GTSVM and 84%/83% for the SVM. The statistical evaluations show that the GTSVM significantly improves performance of the classification as compared to the SVM.

National Category
Medical Biotechnology
Identifiers
urn:nbn:se:kth:diva-171278 (URN)10.1016/j.medengphy.2015.04.013 (DOI)000357354400007 ()26003286 (PubMedID)2-s2.0-84929643026 (Scopus ID)
Note

QC 20150728

Available from: 2015-07-28 Created: 2015-07-27 Last updated: 2017-12-04Bibliographically approved
Gharehbaghi, A., Ekman, I., Ask, P., Nylander, E. & Janerot Sjöberg, B. (2015). Assessment of aortic valve stenosis severity using intelligent phonocardiography [Letter to the editor]. International Journal of Cardiology, 198, 58-60
Open this publication in new window or tab >>Assessment of aortic valve stenosis severity using intelligent phonocardiography
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2015 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 198, p. 58-60Article in journal, Letter (Refereed) Published
Keywords
Intelligent phonocardiography, Heart sound, Phonocardiography, Aortic stenosis, Decision support system, Primary healthcare centers
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:kth:diva-173751 (URN)10.1016/j.ijcard.2015.06.126 (DOI)000360319900020 ()26151715 (PubMedID)2-s2.0-84940434880 (Scopus ID)
Note

QC 20150922

Available from: 2015-09-22 Created: 2015-09-18 Last updated: 2017-12-01Bibliographically approved
Grishenkov, D., Adrian, G. & Janerot Sjöberg, B. (2015). In search of the optimal ultrasound heart perfusion imaging platform. Journal of ultrasound in medicine, 34(9), 1599-1605
Open this publication in new window or tab >>In search of the optimal ultrasound heart perfusion imaging platform
2015 (English)In: Journal of ultrasound in medicine, ISSN 0278-4297, E-ISSN 1550-9613, Vol. 34, no 9, p. 1599-1605Article in journal (Refereed) Published
Abstract [en]

Objective

Quantification of the myocardial perfusion by contrast echocardiography (CEC) remains a challenge. Existing imaging phantoms used to evaluate the performance of ultrasound scanners do not comply with perfusion basics in the myocardium, where perfusion and motion are inherently coupled.

Methods

To contribute towards an improvement, we developed a CEC perfusion imaging platform based on isolated rat heart coupled to the ultrasound scanner. Perfusion was assessed using three different types of contrast agent: dextran-based Promiten®, phospholipid-shelled SonoVue®, and polymer-shelled MB-pH5-RT. The myocardial video-intensity was monitored over time from contrast administration to peak and two characteristic constants were calculated using exponential fit (A representing capillary volume and b representing inflow velocity).

Results

Acquired experimental evidence demonstrates that the application of all three types of contrast agent allow ultrasonic estimation of myocardial perfusion in the isolated rat heart. Video-intensity maps show that an increase in contrast concentration increases the late plateau values, A, mimicking increased capillary volume. Estimated values of the flow, proportional to Axb, increase when the pressure of the perfusate column increases from 80 to 110 cm of water. This finding is in agreement with the true values of the coronary flow increase measured by the flowmeter attached to the aortic cannula.

Conclusions

The described CEC perfusion imaging platform holds promise for standardized evaluation and optimization of ultrasound contrast perfusion imaging where real time inflow curves at low acoustic power semi-quantitatively reflect coronary flow.

National Category
Medical Equipment Engineering Medical Materials Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-159764 (URN)10.7863/ultra.15.14.10019 (DOI)000360777600010 ()2-s2.0-84940377638 (Scopus ID)
Note

QC 20151006. Updated  from accepted to published.

Available from: 2015-02-10 Created: 2015-02-10 Last updated: 2017-12-04Bibliographically approved
Grishenkov, D., Adrian, G., Weitzberg, E., Lundberg, J., Harmark, J., Cerroni, B., . . . Janerot Sjöberg, B. (2015). Ultrasound contrast agent loaded with nitric oxide as a theranostic microdevice: Theranostic contrast agent loaded with nitric oxide. Drug Design, Development and Therapy, 9, 2409-2419
Open this publication in new window or tab >>Ultrasound contrast agent loaded with nitric oxide as a theranostic microdevice: Theranostic contrast agent loaded with nitric oxide
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2015 (English)In: Drug Design, Development and Therapy, ISSN 1177-8881, E-ISSN 1177-8881, Vol. 9, p. 2409-2419Article in journal (Refereed) Published
Abstract [en]

The current study describes novel multifunctional polymer-shelled microbubbles (MBs) loaded with nitric oxide (NO) for integrated therapeutic and diagnostic applications, i.e. theranostics, of myocardial ischemia. We used gas filled MBs with an average diameter of 4 µm stabilized by a biocompatible shell of poly(vinyl)alcohol. In vitro acoustic tests showed a sufficient enhancement of the backscattered power (20 dB) acquired from the MBs suspension. The values of attenuation coefficient (0.8 dB/cm MHz) and phase velocities (1517 m/s) were comparable to those reported for the soft tissue. Moreover, polymer MBs demonstrate increased stability compared to clinically approved contrast agents with fracture threshold of about 900 kPa. In vitro chemiluminescence measurements demonstrated that dry powder of NO-loaded MBs releases its gas content in about 2 hours following an exponential decay profile with an exponential time constant equal 36 min. The application of high power ultrasound pulse (MI=1.2) on the MBs resuspended in saline decreases the exponential time constant from 55 to 4 min in air saturated solution and from 17 to 10 min in degased solution. Thus, ultrasound-triggered release of NO is achieved. Cytotoxicity tests indicate that phagocytosis of the MBs by macrophages starts within 6 to 8 hours. This is suitable time for initial diagnostics, treatment and monitoring of the therapeutic effect using single injection of the proposed multifunctional MBs.

National Category
Medical Equipment Engineering Medical Materials
Identifiers
urn:nbn:se:kth:diva-159765 (URN)10.2147/DDDT.S77790 (DOI)000353631900001 ()2-s2.0-84929178166 (Scopus ID)
Note

QC 20150807. Updated from accepted to published.

Available from: 2015-02-10 Created: 2015-02-10 Last updated: 2017-12-04Bibliographically approved
Larsson, M. K., Larsson, M., Nowak, G., Paradossi, G., Brodin, L.-Å., Janerot Sjöberg, B., . . . Bjällmark, A. (2014). Endocardial border delineation capability of a novel multimodal polymer-shelled contrast agent. Cardiovascular Ultrasound, 12, 24
Open this publication in new window or tab >>Endocardial border delineation capability of a novel multimodal polymer-shelled contrast agent
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2014 (English)In: Cardiovascular Ultrasound, ISSN 1476-7120, E-ISSN 1476-7120, Vol. 12, p. 24-Article in journal (Refereed) Published
Abstract [en]

Background: A novel polymer-shelled contrast agent (CA) with multimodal and target-specific potential was developed recently. To determine its ultrasonic diagnostic features, we evaluated the endocardial border delineation as visualized in a porcine model and the concomitant effect on physiological variables. Methods: Three doses of the novel polymer-shelled CA (1.5 ml, 3 ml, and 5 ml [5 x 10(8) microbubbles (MBs)/ml]) and the commercially available CA SonoVue (1.5 ml [2-5 x 10(8) MBs/ml]) were used. Visual evaluations of ultrasound images of the left ventricle were independently performed by three observers who graded each segment in a 6-segment model as either 0 = not visible, 1 = weakly visible, or 2 = visible. Moreover, the duration of clinically useful contrast enhancement and the left ventricular opacification were determined. During anesthesia, oxygen saturation, heart rate, and arterial pressure were sampled every minute and the effect of injection of CA on these physiological variables was evaluated. Results: The highest dose of the polymer-shelled CA gave results comparable to SonoVue. Thus, no significant difference in the overall segment score distribution (2-47-95 vs. 1-39-104), time for clinically sufficient contrast enhancement (20-40 s for both) and left ventricular overall opacification was found. In contrast, when comparing the endocardial border delineation capacity for different regions SonoVue showed significantly higher segment scores for base and mid, except for the mid region when injecting 1.5 ml of the polymer-shelled CA. Neither high nor low doses of the polymer-shelled CA significantly affected the investigated physiological variables. Conclusions: This study demonstrated that the novel polymer-shelled CA can be used in contrast-enhanced diagnostic imaging without influence on major physiological variables.

Keywords
Contrast agent, Echocardiography, Endocardial border delineation, Microbubbles, Polyvinyl alcohol, Porcine, Ultrasound
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:kth:diva-148611 (URN)10.1186/1476-7120-12-24 (DOI)000338893900001 ()2-s2.0-84910120890 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 3MiCRON (245572)
Note

QC 20150401

Available from: 2014-08-12 Created: 2014-08-11 Last updated: 2017-12-05Bibliographically approved
Li, Y., Tesselaar, E., Borges, J. B., Böhm, S. H., Sjöberg, F. & Janerot-Sjöberg, B. (2014). Hyperoxia affects the regional pulmonary ventilation/perfusion ratio: an electrical impedance tomography study. Acta Anaesthesiologica Scandinavica, 58(6), 716-725
Open this publication in new window or tab >>Hyperoxia affects the regional pulmonary ventilation/perfusion ratio: an electrical impedance tomography study
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2014 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 58, no 6, p. 716-725Article in journal (Refereed) Published
Abstract [en]

Background The way in which hyperoxia affects pulmonary ventilation and perfusion is not fully understood. We investigated how an increase in oxygen partial pressure in healthy young volunteers affects pulmonary ventilation and perfusion measured by thoracic electrical impedance tomography (EIT). Methods Twelve semi-supine healthy male volunteers aged 21-36 years were studied while breathing room air and air-oxygen mixtures (FiO2) that resulted in predetermined transcutaneous oxygen partial pressures (tcPO2) of 20, 40 and 60kPa. The magnitude of ventilation (Zv) and perfusion (ZQ)-related changes in cyclic impedance variations, were determined using an EIT prototype equipped with 32 electrodes around the thorax. Regional changes in ventral and dorsal right lung ventilation (V) and perfusion (Q) were estimated, and V/Q ratios calculated. Results There were no significant changes in Zv with increasing tcPO2 levels. ZQ in the dorsal lung increased with increasing tcPO2 (P=0.01), whereas no such change was seen in the ventral lung. There was a simultaneous decrease in V/Q ratio in the dorsal region during hyperoxia (P=0.04). Two subjects did not reach a tcPO2 of 60kPa despite breathing 100% oxygen. Conclusion These results indicate that breathing increased concentrations of oxygen induces pulmonary vasodilatation in the dorsal lung even at small increases in FiO2. Ventilation remains unchanged. Local mismatch of ventilation and perfusion occurs in young healthy men, and the change in ventilation/perfusion ratio can be determined non-invasively by EIT.

Keywords
Cerebral-Blood-Flow, Lung Perfusion, Ventilatory Response, Supplemental Oxygen, Healthy-Volunteers, Stimulus-Response, Piglet Model, Circulation, Collapse, Hypoxia
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:kth:diva-148363 (URN)10.1111/aas.12323 (DOI)000337967300011 ()2-s2.0-84903183090 (Scopus ID)
Note

QC 20140806

Available from: 2014-08-06 Created: 2014-08-05 Last updated: 2017-12-05Bibliographically approved
Kothapalli, V. V., Daeichin, V., Mastik, F., Brodin, L.-Å., Janerot Sjöberg, B., Paradossi, G., . . . Grishenkov, D. (2014). Unique pumping-out fracturing mechanism of a polymer-shelled contrast agent: An acoustic characterization and optical visualization. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 62(3), 451-462, Article ID 7055440.
Open this publication in new window or tab >>Unique pumping-out fracturing mechanism of a polymer-shelled contrast agent: An acoustic characterization and optical visualization
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2014 (English)In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 62, no 3, p. 451-462, article id 7055440Article in journal (Refereed) Published
Abstract [en]

This work describes the fracturing mechanism of air-filled microbubbles (MBs) encapsulated by a cross-linked poly(vinyl alcohol) (PVA) shell. The radial oscillation and fracturing events following the ultrasound exposure were visualized with an ultrahigh-speed camera, and backscattered timedomain signals were acquired with the acoustic setup specific for harmonic detection. No evidence of gas emerging from defects in the shell with the arrival of the first insonation burst was found. In optical recordings, more than one shell defect was noted, and the gas core was drained without any sign of air extrusion when several consecutive bursts of 1 MPa amplitude were applied. In acoustic tests, the backscattered peak-to-peak voltage gradually reached its maximum and exponentially decreased when the PVA-based MB suspension was exposed to approximately 20 consecutive bursts arriving at pulse repetition frequencies of 100 and 500 Hz. Taking into account that the PVA shell is porous and possibly contains large air pockets between the cross-linked PVA chains, the aforementioned acoustic behavior might be attributed to pumping gas from these pockets in combination with gas release from the core through shell defects. We refer to this fracturing mechanism as pumping-out behavior, and this behavior could have potential use for the local delivery of therapeutic gases, such as nitric oxide.

National Category
Medical Equipment Engineering Medical Image Processing Medical Materials
Identifiers
urn:nbn:se:kth:diva-159768 (URN)10.1109/TUFFC.2014.006732 (DOI)000351446800006 ()2-s2.0-84924942910 (Scopus ID)
Note

The study was financed by EU-grants (3MiCRON ) and strategic money from the Karolinska Institutet.

QC 20150409

Available from: 2015-02-10 Created: 2015-02-10 Last updated: 2017-12-04Bibliographically approved
Broomé, M., Maksuti, E., Bjällmark, A., Frenckner, B. & Janerot-Sjöberg, B. (2013). Closed-loop real-time simulation model of hemodynamics and oxygen transport in the cardiovascular system. Biomedical engineering online, 12(1), 69
Open this publication in new window or tab >>Closed-loop real-time simulation model of hemodynamics and oxygen transport in the cardiovascular system
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2013 (English)In: Biomedical engineering online, ISSN 1475-925X, E-ISSN 1475-925X, Vol. 12, no 1, p. 69-Article in journal (Refereed) Published
Abstract [en]

Background: Computer technology enables realistic simulation of cardiovascular physiology. The increasing number of clinical surgical and medical treatment options imposes a need for better understanding of patient-specific pathology and outcome prediction. Methods: A distributed lumped parameter real-time closed-loop model with 26 vascular segments, cardiac modelling with time-varying elastance functions and gradually opening and closing valves, the pericardium, intrathoracic pressure, the atrial and ventricular septum, various pathological states and including oxygen transport has been developed. Results: Model output is pressure, volume, flow and oxygen saturation from every cardiac and vascular compartment. The model produces relevant clinical output and validation of quantitative data in normal physiology and qualitative directions in simulation of pathological states show good agreement with published data. Conclusion: The results show that it is possible to build a clinically relevant real-time computer simulation model of the normal adult cardiovascular system. It is suggested that understanding qualitative interaction between physiological parameters in health and disease may be improved by using the model, although further model development and validation is needed for quantitative patient-specific outcome prediction.

Keywords
Cardiovascular simulation, Time-varying elastance functions, Lumped parameter model, Valve model, Oxygen transport model, Computer simulation
National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-128495 (URN)10.1186/1475-925X-12-69 (DOI)000323346300001 ()2-s2.0-84882957482 (Scopus ID)
Funder
Swedish Research Council, 2012-2800
Note

QC 20130916

Available from: 2013-09-16 Created: 2013-09-12 Last updated: 2017-12-06Bibliographically approved
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