| 1. |
- Romantsik, Olga, et al.
(author)
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The heme and radical scavenger α1-microglobulin (A1M) confers early protection of the immature brain following preterm intraventricular hemorrhage
- 2019
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In: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 16:1
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Journal article (peer-reviewed)abstract
- Background: Germinal matrix intraventricular hemorrhage (GM-IVH) is associated with cerebro-cerebellar damage in very preterm infants, leading to neurodevelopmental impairment. Penetration, from the intraventricular space, of extravasated red blood cells and extracellular hemoglobin (Hb), to the periventricular parenchyma and the cerebellum has been shown to be causal in the development of brain injury following GM-IVH. Furthermore, the damage has been described to be associated with the cytotoxic nature of extracellular Hb-metabolites. To date, there is no therapy available to prevent infants from developing either hydrocephalus or serious neurological disability. Mechanisms previously described to cause brain damage following GM-IVH, i.e., oxidative stress and Hb-metabolite toxicity, suggest that the free radical and heme scavenger α1-microglobulin (A1M) may constitute a potential neuroprotective intervention. Methods: Using a preterm rabbit pup model of IVH, where IVH was induced shortly after birth in pups delivered by cesarean section at E29 (3 days prior to term), we investigated the brain distribution of recombinant A1M (rA1M) following intracerebroventricular (i.c.v.) administration at 24 h post-IVH induction. Further, short-term functional protection of i.c.v.-administered human A1M (hA1M) following IVH in the preterm rabbit pup model was evaluated. Results: Following i.c.v. administration, rA1M was distributed in periventricular white matter regions, throughout the fore- and midbrain and extending to the cerebellum. The regional distribution of rA1M was accompanied by a high co-existence of positive staining for extracellular Hb. Administration of i.c.v.-injected hA1M was associated with decreased structural tissue and mitochondrial damage and with reduced mRNA expression for proinflammatory and inflammatory signaling-related genes induced by IVH in periventricular brain tissue. Conclusions: The results of this study indicate that rA1M/hA1M is a potential candidate for neuroprotective treatment following preterm IVH.
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| 2. |
- Albinsson, John, et al.
(author)
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A combination of parabolic and grid slope interpolation for 2D tissue displacement estimations
- 2017
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In: Medical & Biological Engineering & Computing. - : Springer Science and Business Media LLC. - 0140-0118 .- 1741-0444. ; 55:8, s. 1327-1338
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Journal article (peer-reviewed)abstract
- Parabolic sub-sample interpolation for 2D block-matching motion estimation is computationally efficient. However, it is well known that the parabolic interpolation gives a biased motion estimate for displacements greater than |y.2| samples (y = 0, 1, …). Grid slope sub-sample interpolation is less biased, but it shows large variability for displacements close to y.0. We therefore propose to combine these sub-sample methods into one method (GS15PI) using a threshold to determine when to use which method. The proposed method was evaluated on simulated, phantom, and in vivo ultrasound cine loops and was compared to three sub-sample interpolation methods. On average, GS15PI reduced the absolute sub-sample estimation errors in the simulated and phantom cine loops by 14, 8, and 24% compared to sub-sample interpolation of the image, parabolic sub-sample interpolation, and grid slope sub-sample interpolation, respectively. The limited in vivo evaluation of estimations of the longitudinal movement of the common carotid artery using parabolic and grid slope sub-sample interpolation and GS15PI resulted in coefficient of variation (CV) values of 6.9, 7.5, and 6.8%, respectively. The proposed method is computationally efficient and has low bias and variance. The method is another step toward a fast and reliable method for clinical investigations of longitudinal movement of the arterial wall.
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| 3. |
- Albinsson, John, et al.
(author)
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Iterative 2D tissue motion tracking in ultrafast ultrasound imaging
- 2018
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In: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 8:5
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Journal article (peer-reviewed)abstract
- In order to study longitudinal movement and intramural shearing of the arterial wall with a Lagrangian viewpoint using ultrafast ultrasound imaging, a new tracking scheme is required. We propose the use of an iterative tracking scheme based on temporary down-sampling of the frame-rate, anteroposterior tracking, and unbiased block-matching using two kernels per position estimate. The tracking scheme was evaluated on phantom B-mode cine loops and considered both velocity and displacement for a range of down-sampling factors (k = 1-128) at the start of the iterations. The cine loops had a frame rate of 1300-1500 Hz and were beamformed using delay-and-sum. The evaluation on phantom showed that both the mean estimation errors and the standard deviations decreased with an increasing initial down-sampling factor, while they increased with an increased velocity or larger pitch. A limited in vivo study shows that the major pattern of movement corresponds well with state-of-the-art low frame rate motion estimates, indicating that the proposed tracking scheme could enable the study of longitudinal movement of the intima-media complex using ultrafast ultrasound imaging, and is one step towards estimating the propagation velocity of the longitudinal movement of the arterial wall.
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| 4. |
- Albinsson, John, et al.
(author)
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Tracking Performance of Several Combinations of Common Evaluation Metrics and Sub-pixel Methods
- 2015
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In: 16th Nordic-Baltic Conference on Biomedical Engineering. - Cham : Springer International Publishing. - 1680-0737. ; 48, s. 13-16, s. 13-16
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Conference paper (peer-reviewed)abstract
- Motion estimation in a series of consecutive images is used in a variety of areas, e.g. video compression and investigation of tissue characteristics and organ function in medical images. Several methods exist both for estimating motions on a pixel level, e.g. block-matching in which two blocks in consecutive images are compared by an evaluation metric, and on a sub-pixel level. In this paper, we have evaluated the tracking performance of all combinations between three evaluation metrics and eight sub-pixel estimation methods. The tracking performance of a sub-pixel method varies depending on the evaluation metric used. This indicates that a reported tracking performance for a sub-pixel estimation method can be significantly different when combined with another evaluation metric. Also there is a large variation in the time needed for the motion estimations depending primarily on the sub-pixel method used but also on the evaluation metric.
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| 5. |
- Andersson, Roger, et al.
(author)
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B-field energy dependent phase lag dispersion in magnetomotive ultrasound imaging
- 2015
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In: 2015 IEEE International Ultrasonics Symposium (IUS). - 1948-5719.
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Conference paper (peer-reviewed)abstract
- Magnetomotive ultrasound imaging is an emerging technique where superparamagnetic iron oxide nanoparticles can be used as an ultrasound contrast agent. A time-varying external magnetic field acts to move tissue embedded particles, and ultrasound is used to detect the resulting tissue movement. In experimental phantom studies we have observed a phase lag dispersion in the magnetomotive response in respect to applied time-varying magnetic field (B-field). We hypothesize that this dispersion is triggered by the strength of the applied B-field in combination with concentration of embedded nanoparticles in the region. The cohort response of the nanoparticles aligns as the magnetic field gets more energetic. Moreover, the tightening of the phase response indicate an asymptotic tapering towards a phase limit.
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| 6. |
- Andersson, Roger, et al.
(author)
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Cross-correlation detection improves spatial delineation and enables high resolution tracking of temporal events in magnetomotive ultrasound imaging
- 2017
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In: 2017 IEEE International Ultrasonics Symposium, IUS 2017. - 9781538633830
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Conference paper (peer-reviewed)abstract
- Magnetomotive ultrasound (MM US) imaging is a method whereby superparamagnetic iron oxide nanoparticles (SPIO NP) are used as a contrast agent. By applying an external magnetic field the particles are set in motion together with their surroundings. The induced movement is detected with ultrasound, and for the case of harmonic excitation of the magnetic source, quadrature detection (lock-in plus phase gating) can recover the magnetomotive signal (doi:10.1109/TUFFC.2013.2591). Here, we propose instead the use of cross-correlation for detection, and report the potential benefits compared to the previous approach.
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| 7. |
- Andersson, Roger, et al.
(author)
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Effect of nanoparticle size and magnetic field strength on the displacement signal in magnetomotive ultrasound imaging
- 2016
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In: 2016 IEEE International Ultrasonics Symposium, IUS 2016. - 9781467398978 ; 2016-November
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Conference paper (peer-reviewed)abstract
- Magnetomotive ultrasound imaging is an emerging technique where superparamagnetic iron oxide nanoparticles can be used as an ultrasound contrast agent. A time-varying external magnetic field acts to move tissue embedded particles, and ultrasound is used to detect the resulting tissue movement. In this experimental phantom study we observed a variation in the magnetomotive response in respect to physical size of the embedded superparamagnetic iron oxide nanoparticles. Given the same Fe concentration a weaker response, by a factor of 2, was detected with the larger nanoparticles. However, approximately seven times larger response remains, given the volume ratio between particles, implying a seven times larger response per binding event. We hypothesize that this can have bearing in molecular imaging.
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| 8. |
- Baianstovu, Rúna Í, 1961-, et al.
(author)
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Heder och samhälle : Det hedersrelaterade våldets och förtryckets uttryck och samhällets utmaningar
- 2019
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Reports (peer-reviewed)abstract
- Denna bok är resultatet av den hittills mest omfattande studien av det hedersrelaterade våldets uttryck, former och mekanismer som genomförts i Sverige. Studien bygger på kvalitativa och kvantitativa delstudier och har gjorts på uppdrag av Stockholms, Göteborgs och Malmö stad 2017–2018. Bredden gör studien unik inom detta område. Den kvalitativa datainsamlingen: 235 nyckelpersoner med djupgående kunskap om hedersrelaterat våld och förtryck har intervjuats i 95 öppna intervjuer. Några av intervjupersonerna har kunskap utifrån sitt arbete eller från sitt engagemang i föreningar. Andra har kunskap på grund av egen erfarenhet av livet i en hederskontext och av utsatthet för våld och förtryck. Några har båda dessa positioner. Den kvantitativa datainsamlingen: 6 002 ungdomar i årskurs nio har besvarat en enkät om relationer, begränsningar och olika former av utsatthet i hemmet, skolan och på fritiden. Det sammantagna resultatet visar att människor med olika etniska tillhörigheter, trosuppfattningar, funktionsnedsättningar, sexuell läggning, ålder och socioekonomiska förhållanden lever med våldsutsatthet och normer som förtrycker dem. Vidare visas att hedersrelaterat våld och förtryck är uttryck för olika svårigheter som kan sammanfattas med begreppen inneslutning och mobilitet på individ-, grupp- och samhällsnivå och i samspelet mellan dessa. Inneslutning och mobilitet betecknar att våldsutövning ökar i introverta eller inneslutna grupper där samspelet med andra grupper är låg; dvs. att mobiliteten är låg. Hedersrelaterat våld och förtryck närs bland annat av minoritetsskap, särskilt i kombination med kollektiv statslöshet, krig, migration och segregation. Social, ekonomisk och politisk rörlighet urholkar däremot våldsnormerna och minskar våldsanvändandet. Sammantaget visar resultatet att hedersrelaterat våld och förtryck drabbar individer på ett flertal sätt och att samhället genom socialpolitiken bör ta ett förnyat ansvar på flera nivåer, både akut, kortsiktigt och långsiktigt.
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| 9. |
- Bengtsson, Alexander, et al.
(author)
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Characterization and modeling of acousto-optic signal strengths in highly scattering media
- 2019
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In: Biomedical Optics Express. - 2156-7085. ; 10:11, s. 5565-5584
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Journal article (peer-reviewed)abstract
- Ultrasound optical tomography (UOT) is an imaging technique based on the acousto-optic effect that can perform optical imaging with ultrasound resolution inside turbid media, and is thus interesting for biomedical applications, e.g. for assessing tissue blood oxygenation. In this paper, we present near background free measurements of UOT signal strengths using slow light filter signal detection. We carefully analyze each part of our experimental setup and match measured signal strengths with calculations based on diffusion theory. This agreement between experiment and theory allows us to assert the deep tissue imaging potential of similar to 5 cm for UOT of real human tissues predicted by previous theoretical studies [Biomed. Opt. Express 8, 4523 (2017)] with greater confidence, and indicate that future theoretical analysis of optimized UOT systems can be expected to be reliable. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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| 10. |
- Cinthio, Magnus, et al.
(author)
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Individuell betygsättning av grupparbeten inom högre utbildning
- 2016
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In: 9:e Pedagogiska Inspirationskonferensen 2016. - 2003-3761 .- 2003-377X. ; 9
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Conference paper (peer-reviewed)abstract
- Det finns många fördelar med att låta studenter vid högre utbildning gruppvis genomföra projektarbete med öppna frågeställningar. Det finns emellertid problem med att sätta individuella betyg i en kurs som till stor del examineras genom det gruppvisa projektarbetet. I kursen EEMA01 Medicinteknisk design ges valet av undervisningsform naturligt av lärandemålens karaktär men betygssättningen böravspegla individens bidrag i grupprocessen. Efter kritik från missnöjda studenter har lärarlaget i kursen nu utarbetat ett förslag till komplettering för att påverka betygsättning som uppfattats som orättvis.
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