| 1. |
- Cinthio, Magnus, et al.
(författare)
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New improved method for 2D arterial wall movement measurements
- 2005
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Ingår i: Proceedings of the International Federation for Medical & Biomedical Engineering. 13th Nordic Baltic Conference on Biomedical Engineering and Medical Physics. - 9173059102 ; , s. 117-118
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Konferensbidrag (refereegranskat)abstract
- We have recently reported that the inner layers of the arteries, the intima-media complex, of common carotid artery, move as much in the longitudinal direction as in the radial direction, during the cardiac cycle. In order to study this phenomenon we have developed a high-resolution ultrasonic method that can simultaneously record both the longitudinal and the radial movements of the arterial wall non-invasively in vivo. However, in young individuals with large movements and with thin intima-media complex it happens sometimes that the echoes from the adventitia region interfere. To be able to minimise the size of the region-of-interest in the radial direction, we suggest that the radial movement of the arterial vessel is first measured and that the radial movement is used as a priori information when the longitudinal movement is measured. The mean difference between the two methods is 8 and 2 standard deviation is 24 μm
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| 2. |
- Jansson, Tomas, et al.
(författare)
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An ultrasonic method for detection of fluid properties in the paranasal sinuses
- 2005
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Ingår i: Proceedings of the International Federation for Medical & Biomedical Engineering. 13th Nordic Baltic Conference on Biomedical Engineering and Medical Physics. - 9173059102 ; , s. 115-116
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Konferensbidrag (refereegranskat)abstract
- We propose a method for detection of the degree of infection in the paranasal sinuses utilizing a previously published method whereby the viscosity in a sealed container may be measured using an ultrasound Doppler method. As ultrasound propagates in a liquid medium, due to attenuation, the resulting pressure gradient will cause the liquid to move in the propagation direction - the wellknown effect of acoustic streaming. The streaming velocity will, for a given acoustic output, be proportional to the viscosity of the fluid. In this study, we verify that acoustic streaming can be induced in an anthropomorphic sinus phantom cast from a human cranium. The sinus phantom was made from agar with added graphite providing sound attenuation prior to the sinus cavity corresponding to an in vivo situation. A number of water-glycerol solutions with scattering particles, were prepared to mimic a clinically interesting range of viscosities (7-47 mPas). Using a 4.2 MHz continuous wave Doppler probe, clearly detectable Doppler shifts in the range of 6.5 to 20 Hz were recorded. A linear relationship was found between the Doppler shifts and 1/viscosity (R2=0.94, corrected for the square-law dependence of sound speed variation due to varying glycerol concentration)
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| 3. |
- Jansson, Tomas, et al.
(författare)
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Investigation of the fetal heart circulation in an animal model using contrast enhanced ultrasound
- 2005
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Ingår i: Proceedings of the International Federation for Medical & Biomedical Engineering. 13th Nordic Baltic Conference on Biomedical Engineering and Medical Physics. - 9173059102 ; , s. 125-126
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Konferensbidrag (refereegranskat)abstract
- To assess the distribution of blood from the umbilical vein (UMV), inferior vena cava (IVC) and superior vena cava (SVC) to either side of the fetal lamb heart by using ultrasound enhanced contrast agent imaging. By injection of ultrasound contrast agents (UCA) in UMV, IVC or SVC, the blood from these vessels was tracked, as it then was highly echogenic. By evaluating the image intensity within the heart ventricles, the relative concentrations of blood could be determined. The study was performed in 19 near term fetal lambs of mixed breed, with a mean gestational age of 136 days (range 134-136). Ultrasound contrast agent was injected at a constant rate of 1 ml/min, to ensure that a constant level of contrast agent would be obtained in both sides of the heart. Results: the median percentages of blood distributed to the left ventricle when injecting contrast in UMV, IVC, and SVC, was 68%, 67%, and 21% respectively. These numbers compare well with previously published data, except the recorded percentage distributed from the IVC. This could be a methodological error as well as a result of the mild hypoxia, or an actual increased capacity of the left ventricle at this gestational age
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| 4. |
- Nilsson, M, et al.
(författare)
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Versatile microchip utilising ultrasonic manipulation of microparticles
- 2005
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Ingår i: Proceedings of the International Federation for Medical & Biomedical Engineering. 13th Nordic Baltic Conference on Biomedical Engineering and Medical Physics. - 9173059102 ; , s. 123-124
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Konferensbidrag (refereegranskat)abstract
- This paper presents the concept and initial work on a microfluidic platform for bead-based analysis of biological sample. The core technology in this project is ultrasonic manipulation and trapping of particle in array configurations by means of acoustic forces. The platform is ultimately aimed for parallel multistep bioassays performed on biochemically activated microbeads (or particles) using submicrolitre sample volumes. A first prototype with three individually controlled particle trapping sites has been developed and evaluated. Standing ultrasonic waves were generated across a microfluidic channel by integrated PZT ultrasonic microtransducers. Particles in a fluid passing a transducer were drawn to pressure minima in the acoustic field, thereby being trapped and confined laterally over the transducer. It is anticipated that acoustic trapping using integrated transducers can be exploited in miniaturised total chemical analysis systems (μTAS), where e.g. microbeads with immobilised antibodies can be trapped in arrays and subjected to minute amounts of sample followed by a reaction, detected using fluorescence. Preliminary results indicate that the platform is capable of handling live cells as well as microbeads. A first model bioassay with detection of fluorescein marked avidin binding to trapped biotin beads has been evaluated
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