| 1. |
- Gram, Magnus, et al.
(author)
-
Extracellular hemoglobin - mediator of inflammation and cell death in the choroid plexus following preterm intraventricular hemorrhage
- 2014
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In: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 11
-
Journal article (peer-reviewed)abstract
- Background: Intraventricular hemorrhage (IVH) with post-hemorrhagic ventricular dilatation (PHVD) is a major cause of neurodevelopmental impairment and mortality in preterm infants. The mechanisms leading to PHVD and brain damage remain largely unknown. The choroid plexus and the ependyma, which constitute an essential part of the blood-brain barrier (BBB), are the first structures to encounter the damaging effects of extravasated blood. The breakdown of the BBB is a critical upstream event leading to brain damage following IVH. In this study we investigated the impact of hemorrhage and hemoglobin (Hb) metabolites on the choroid plexus epithelium. Methods: Using a preterm rabbit pup model of IVH, the structural and functional integrity, cellular, inflammatory and oxidative response of the choroid plexus, at 24 and 72 hours following IVH + PHVD, were investigated. In order to further characterize cellular and molecular mechanisms, primary human choroid plexus epithelial cells were exposed to cerebrospinal fluid (CSF) from preterm infants with IVH as well as to Hb-metabolites. Finally, the blocking effects of the Hb-scavenger haptoglobin (Hp) were investigated both in vivo and in vitro. Results: Following IVH + PHVD, an up-regulation of mRNA for the receptor-related genes TLR-4, IL1R1, FAS, the transcription factor NF-kappa beta and for the pro-inflammatory and chemotactic effector molecules, IL-1 beta, TNF alpha, MCP-1, IL-8, and IL-6 was observed in the choroid plexus at 24 and 72 hours. This was associated with structural disintegration, caspase activation and cell death in the choroid plexus epithelium. In vitro characterization of choroid plexus epithelial cells, following exposure to hemorrhagic CSF and to the Hb-metabolites metHb and heme, displayed apoptotic and necrotic cell death and an up-regulation of receptor-related and inflammatory effector molecules similar to that observed in vivo following IVH + PHVD. Intraventricular injection of the Hb-scavenger Hp in vivo and co-incubation with Hp in vitro reversed or reduced the cellular activation, inflammatory response, structural damage and cell death. Conclusion: Hb-metabolites are important causal initiators of cell death following IVH and removal or scavenging of Hb-metabolites may present an efficient means to reduce the damage to the immature brain following IVH.
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| 2. |
- Gram, Magnus, et al.
(author)
-
Hemoglobin induces inflammation after preterm intraventricular hemorrhage by methemoglobin formation.
- 2013
-
In: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 10:Aug.,6
-
Journal article (peer-reviewed)abstract
- Cerebral intraventricular hemorrhage (IVH) is a major cause of severe neurodevelopmental impairment in preterm infants. To date, no therapy is available that prevents infants from developing serious neurological disability following IVH. Thus, to develop treatment strategies for IVH, it is essential to characterize the initial sequence of molecular events that leads to brain damage. In this study, we investigated extracellular hemoglobin (Hb) as a causal initiator of inflammation in preterm IVH.
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| 3. |
- Romantsik, Olga, et al.
(author)
-
The heme and radical scavenger α1-microglobulin (A1M) confers early protection of the immature brain following preterm intraventricular hemorrhage
- 2019
-
In: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 16:1
-
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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| 4. |
- Sveinsdottir, Snjolaug, et al.
(author)
-
Altered Expression of Aquaporin 1 and 5 in the Choroid Plexus following Preterm Intraventricular Hemorrhage.
- 2014
-
In: Developmental Neuroscience. - : S. Karger AG. - 1421-9859 .- 0378-5866. ; 36:6, s. 542-551
-
Journal article (peer-reviewed)abstract
- Intraventricular hemorrhage (IVH) with posthemorrhagic ventricular dilatation (PHVD) is a common cause of hydrocephalus in infants. Dysregulation of cerebrospinal fluid (CSF) production by the choroid plexus may contribute to the development of PHVD. The aquaporins (AQPs), transmural water transporting proteins, are believed to contribute to CSF production. The aim of the study was to characterize the expression and localization of AQP1, 4 and 5 in the choroid plexus following preterm IVH. Using a preterm rabbit pup model, the mRNA expression, protein level and localization of AQP1, 4 and 5 were investigated in the choroid plexus at 24 and 72 h following IVH with PHVD. Further, AQP1, 4 and 5 expression were characterized in primary human plexus epithelial cells exposed to CSF from preterm human infants with IVH and to hemoglobin metabolites. IVH with PHVD in the immature brain caused a downregulation of AQP1 mRNA, the key AQP in CSF production, but an upregulation of AQP1 protein level with apical epithelial cell localization. Notably, AQP5 was expressed in the choroid plexus with upregulated mRNA expression and protein levels during PHVD with apical epithelial cell localization. Analysis of human choroid plexus epithelial cells in vitro, following exposure to posthemorrhagic CSF and to hemin, displayed results concordant with those observed in vivo, i.e. downregulation of AQP1 mRNA and upregulation of AQP5 mRNA expression. AQP4 was neither detectable in vivo nor in vitro. The changes observed in AQP1 and AQP5 expression in the choroid plexus suggest an adaptive response following IVH with possible functional implications for the development of PHVD. © 2014 S. Karger AG, Basel.
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| 5. |
- Ahlgren, Åsa Rydén, et al.
(author)
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Response of the carotid artery longitudinal motion to submaximal physical activity in healthy humans-Marked changes already at low workload
- 2023
-
In: Physiological Reports. - : Wiley. - 2051-817X. ; 11:2
-
Journal article (peer-reviewed)abstract
- The longitudinal motion of the arterial wall, that is, the displacement of the arterial wall along the artery, parallel to blood flow, is still largely unexplored. The magnitude and nature of putative changes in longitudinal motion of the arterial wall in response to physical activity in humans remain unknown. The aim of this study was therefore to study the longitudinal motion of the carotid artery wall during physical activity in healthy humans. Using in-house developed non-invasive ultrasonic methods, the longitudinal motion of the intima-media complex and the diameter changes of the right common carotid artery (CCA) in 40 healthy volunteers (20 volunteers aged 22-35 years; 20 volunteers aged 55-68 years) were assessed at rest and during submaximal supine bicycle exercise. In a subset of the subjects (n = 18) also intramural shear strain were analyzed. The longitudinal motion of the intima-media complex underwent marked changes in response to physical activity, already at low workload; with most evident a marked increase of the first antegrade displacement (p < 0.001) in early systole. Likewise, the corresponding shear strain also increased significantly (p = 0.004). The increase in longitudinal motion showed significant correlation to increase in blood pressure, but not to blood flow velocity or wall shear stress. In conclusion, physical activity markedly influences the longitudinal motion of the carotid artery wall in healthy humans already at low load. A possible "cushioning" function as well as possible implications for the function of the vasa vasorum, endothelium, and smooth muscle cells and extracellular matrix of the media, are discussed.
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| 6. |
- 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
-
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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| 7. |
- Albinsson, John, et al.
(author)
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Combined use of Iteration, Quadratic Interpolation and an Extra Kernel for high-resolution 2D particle tracking : a first evaluation
- 2010
-
In: 2010 ieee international ultrasonics symposium. - New York : IEEE Press. - 9781457703829 ; , s. 2000-2003
-
Conference paper (peer-reviewed)abstract
- A novel 2D particle tracking method, that uses 1) iteration, 2) fast quadratic sub-pixel estimation (with only 28 multiplications per movement), and 3) a previous kernel, has been evaluated and compared with a full-search block-matching method. The comparison with high-frequency ultrasound data (40 MHz) was conducted in silico and on phantoms, which comprised lateral, diagonal, and ellipsoidal movement patterns with speeds of 0–15 mm/s. The mean tracking error was reduced by 68% in silico and 71% for the phantom measurements. When only sub-pixel estimation was used, the decrease in the tracking error was 61% in silico and 57% for the phantom measurements. As well as decreasing the tracking error, the new method only used 70% of the computational time needed by the full-search block-matching method. With a fast method having good tracking ability for high-frequency ultrasound data, we now have a tool to better investigate tissue movements and its dynamic functionality.
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| 8. |
- Albinsson, John, et al.
(author)
-
Improved tracking performance of lagrangian block-matching methodologies using block expansion in the time domain : In silico, phantom and invivo evaluations
- 2014
-
In: Ultrasound in Medicine and Biology. - : Elsevier. - 0301-5629 .- 1879-291X. ; 40:10, s. 2508-2520
-
Journal article (peer-reviewed)abstract
- The aim of this study was to evaluate tracking performance when an extra reference block is added to a basic block-matching method, where the two reference blocks originate from two consecutive ultrasound frames. The use of an extra reference block was evaluated for two putative benefits: (i) an increase in tracking performance while maintaining the size of the reference blocks, evaluated using in silico and phantom cine loops; (ii) a reduction in the size of the reference blocks while maintaining the tracking performance, evaluated using in vivo cine loops of the common carotid artery where the longitudinal movement of the wall was estimated. The results indicated that tracking accuracy improved (mean - 48%, p<0.005 [in silico]; mean - 43%, p<0.01 [phantom]), and there was a reduction in size of the reference blocks while maintaining tracking performance (mean - 19%, p<0.01 [in vivo]). This novel method will facilitate further exploration of the longitudinal movement of the arterial wall. (C) 2014 World Federation for Ultrasound in Medicine & Biology.
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| 9. |
- Albinsson, John, et al.
(author)
-
Iterative 2D tissue motion tracking in ultrafast ultrasound imaging
- 2018
-
In: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 8:5
-
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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| 10. |
- Albinsson, John, et al.
(author)
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Tracking Performance of Several Combinations of Common Evaluation Metrics and Sub-pixel Methods
- 2015
-
In: 16th Nordic-Baltic Conference on Biomedical Engineering. - Cham : Springer International Publishing. - 1680-0737. ; 48, s. 13-16, s. 13-16
-
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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| 11. |
- Andersson, Roger, et al.
(author)
-
B-field energy dependent phase lag dispersion in magnetomotive ultrasound imaging
- 2015
-
In: 2015 IEEE International Ultrasonics Symposium (IUS). - 1948-5719.
-
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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| 12. |
- Andersson, Roger, et al.
(author)
-
Cross-correlation detection improves spatial delineation and enables high resolution tracking of temporal events in magnetomotive ultrasound imaging
- 2017
-
In: 2017 IEEE International Ultrasonics Symposium, IUS 2017. - 9781538633830
-
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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| 13. |
- Andersson, Roger, et al.
(author)
-
Effect of nanoparticle size and magnetic field strength on the displacement signal in magnetomotive ultrasound imaging
- 2016
-
In: 2016 IEEE International Ultrasonics Symposium, IUS 2016. - 9781467398978 ; 2016-November
-
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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| 14. |
- Baianstovu, Rúna Í, 1961-, et al.
(author)
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Heder och samhälle : Det hedersrelaterade våldets och förtryckets uttryck och samhällets utmaningar
- 2019
-
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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| 15. |
- Bengtsson, Alexander, et al.
(author)
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Characterization and modeling of acousto-optic signal strengths in highly scattering media
- 2019
-
In: Biomedical Optics Express. - 2156-7085. ; 10:11, s. 5565-5584
-
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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| 16. |
- Bjarnegård, Niclas, et al.
(author)
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Cardiovascular function in adulthood following intrauterine growth restriction with abnormal fetal blood flow
- 2013
-
In: Ultrasound in Obstetrics and Gynecology. - : Wiley-Blackwell. - 0960-7692 .- 1469-0705. ; 41:2, s. 177-184
-
Journal article (peer-reviewed)abstract
- Objectives To examine whether intrauterine growth restriction (IUGR) is associated with increased cardiovascular risk later in life. Methods We examined 19 young adults (aged 2225 years) who were born at term after IUGR, along with 18 controls. All had been examined previously with fetal Doppler, and in the present follow-up with echocardiography, carotid echo-tracking ultrasound, applanation tonometry, blood pressure and laser Doppler, in order to characterize their cardiac and vascular geometry and/or function. Results The diameter of the ascending aorta and the left ventricular diameter were smaller in the IUGR group, but only ascending aortic diameter remained significantly smaller after adjustment for body surface area (Pandlt;0.05). The aortic pressure augmentation index was higher in the IUGR group (Pandlt;0.05). The common carotid artery diameter, intimamedia thickness and distensibility as well as left ventricular mass and function were similar in the two groups. IUGR status was found to be an independent predictor of ascending aortic diameter. Conclusions IUGR due to placental dysfunction seems to contribute to the higher systolic blood pressure augmentation and the smaller aortic dimensions that are observed in adults more than 20 years later, with possible negative consequences for future left ventricular performance due to increased aortic impedance.
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| 17. |
- Bohman, Elin, et al.
(author)
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Novel Evidence Concerning Lacrimal Sac Movement Using Ultra-High-Frequency Ultrasound Examinations of Lacrimal Drainage Systems
- 2021
-
In: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 37:4, s. 334-340
-
Journal article (peer-reviewed)abstract
- PURPOSE: Current hypothesis regarding the mechanism of active tear drainage is based on studies performed ex vivo or under nonphysiological conditions. Novel ultra-high-frequency ultrasound has the advantage of generating images with superior resolution, enabling measurements of low flow in small vessels, and the tracking of tissue motion in real time. The purpose of this study was to investigate the lacrimal drainage system and active drainage using this modality.METHODS: The upper lacrimal drainage system was investigated with 40-70 MHz ultrasound in 22 eyes in 13 patients. Irrigation confirmed a lacrimal obstruction in 10 eyes. Motion tracking was used to map movement of the lateral lacrimal sac wall and to measure flow when possible.RESULTS: The anatomy of the upper lacrimal drainage system was mapped in vivo, including the proximal canaliculi, which have not previously been imaged. The lacrimal sac lumen is slit shaped in its resting state but is distended when irrigated or if a nasolacrimal duct obstruction is present. Thus, the healthy lacrimal sac is not a cavity, and the medial retinaculum does not act against a stretched structure. Motion tracking visualized the "lacrimal pump," showing that the direction of motion of the lateral lacrimal sac wall is mainly in the sagittal plane during blinking.CONCLUSIONS: Ultra-high-frequency ultrasound allows detailed physiological monitoring of the upper lacrimal drainage system in vivo. Our findings suggest that current theories of active tear drainage need to be reappraised.
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| 18. |
- Bunke, Josefine, et al.
(author)
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Photoacoustic imaging for the monitoring of local changes in oxygen saturation following an adrenaline injection in human forearm skin
- 2021
-
In: Biomedical Optics Express. - 2156-7085. ; 12:7, s. 4084-4096
-
Journal article (peer-reviewed)abstract
- Clinical monitoring of blood oxygen saturation (sO2) is traditionally performed using optical techniques, such as pulse oximetry and diffuse reflectance spectroscopy (DRS), which lack spatial resolution. Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technique that is superior to previous techniques in that it combines optical excitation and acoustic detection, providing a map of chromophore distribution in the tissue. Hitherto, PAI has primarily been used in preclinical studies, and only a few studies have been performed in patients. Its ability to measure sO2 with spatial resolution during local vasoconstriction after adrenaline injection has not yet been investigated. Using PAI and spectral unmixing we characterize the heterogeneous change in sO2 after injecting a local anesthetic containing adrenaline into the dermis on the forearm of seven healthy subjects. In comparison to results obtained using DRS, we highlight contrasting results obtained between the two methods arising due to the so-called ‘window effect’ caused by a reduced blood flow in the superficial vascular plexus. The results demonstrate the importance of spatially resolving sO2 and the ability of PAI to assess the tissue composition in different layers of the skin.
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| 19. |
- Chaudhry, Nadia, et al.
(author)
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Breast Cancer Diagnosis Using Extended-Wavelength–Diffuse Reflectance Spectroscopy (EW-DRS) : Proof of Concept in Ex Vivo Breast Specimens Using Machine Learning
- 2023
-
In: Diagnostics. - 2075-4418. ; 13:19, s. 1-12
-
Journal article (peer-reviewed)abstract
- This study aims to investigate the feasibility of using diffuse reflectance spectroscopy (DRS) to distinguish malignant breast tissue from adjacent healthy tissue, and to evaluate if an extended-wavelength range (450–1550 nm) has an advantage over the standard wavelength range (450–900 nm). Multivariate statistics and machine learning algorithms, either linear discriminant analysis (LDA) or support vector machine (SVM) are used to distinguish the two tissue types in breast specimens (total or partial mastectomy) from 23 female patients with primary breast cancer. EW-DRS has a sensitivity of 94% and specificity of 91% as compared to a sensitivity of 40% and specificity of 71% using the standard wavelength range. The results suggest that DRS can discriminate between malignant and healthy breast tissue, with improved outcomes using an extended wavelength. It is also possible to construct a simple analytical model to improve the diagnostic performance of the DRS technique.
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| 20. |
- Cinthio, Magnus, et al.
(author)
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A Method for Arterial Diameter Change Measurements Using Ultrasonic B-Mode Data.
- 2010
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In: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629. ; 36:9, s. 1504-1512
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Journal article (peer-reviewed)abstract
- Arterial diameter change is related to distending blood pressure and is used in estimation of arterial stiffness parameters. A common technique to track the arterial walls is by integration of wall velocities estimated by different methods using cross correlation or tissue Doppler. However, because of the high pulse repetition frequency and the need for separate pulsing sequences, the B-mode image quality is affected. We have previously developed a fast algorithm for direct measurement of lumen diameter using B-mode images. In this study we have improved the technique to be more robust and also implemented measurements of diameter change, maximum differential wall velocity and relative diameter change of the common carotid artery noninvasively in vivo. The influence of the lateral width of the region of interest (ROI; 1 pixel, 0.1 mm, 0.5 mm, 1 mm, 2.5 mm and 5 mm) was evaluated. Using the optimal lateral width (2.5 mm), the systematic and random differences between two consecutive measurements were 21 mum and 105 mum, respectively, for lumen diameter measurement; -7 mum and 39 mum, respectively, for lumen diameter change measurements; -0.2 mm/s and 0.9 mm/s, respectively, for maximum relative wall velocity; and -0.2 % and 0.8 %, respectively, for measurements of the relative diameter change. The coefficient of variation (CV) was 1.9%, 5.2%, 7.9% and 6.0%, respectively. The study indicates that the reproducibility is sufficient for in vivo studies when the width of the ROI is 1.0 mm or wider. (E-mail: magnus.cinthio@elmat.lth.se).
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| 21. |
- Cinthio, Magnus, et al.
(author)
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A NEW NON-INVASIVE ULTRASONIC METHOD FOR MEASUREMENTS OF LONGITUDINAL LENGTH ALTERATION OF THE ARTERIAL WALL - FIRST IN VIVO TRIAL
- 2008
-
In: Acoustical Imaging. - 0270-5117. ; 29, s. 39-43
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Conference paper (peer-reviewed)abstract
- We have recently shown that there is a previous unknown longitudinal movement present in the arterial wall. We aim now to investigate whether the longitudinal movement causes length alteration of the arterial wall. The objective of this paper was to describe a new non-invasive ultrasonic technique that measures the length alteration of arteries in human in-vivo. Results indicate that a significant length alteration is present in the common carotid artery.
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| 22. |
- Cinthio, Magnus, et al.
(author)
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An automatic method for measurements of arterial intima-media thickness using ultrasonic B-mode data
- 2012
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In: Acoustical Imaging. - Dordrecht : Springer Netherlands. - 9789400726185 - 9789400726192 ; 31, s. 115-122
-
Conference paper (other academic/artistic)abstract
- We have previously developed algorithms that use B-mode cineloops for simultaneous measurements of arterial diameter change and longitudinal movement of the arterial wall. In this study the lumen diameter algorithm was extended to also measure arterial intima-media thickness of the far wall. To optimize the algorithm the influence of the lateral width of the region-of-interest (1 pixel, 0.1 mm, 0.5 mm, 1 mm, 2.5 mm and 5 mm) was evaluated. The algorithm estimated intima-media thickness at diastole automatically by measuring the distance between the two positions where the laterally averaged B-mode intensity envelope crosses a threshold value relative to the maximum amplitudes of the intimal and adventitial echoes, respectively. The sub-pixel resolution is achieved by solving the equation of a straight line between the two samples on either side of the threshold value. The measurements were performed on 20 healthy normotensive volunteers (age 25–57 years) on the common carotid artery 2–3 cm proximal to the bifurcation. For the 2.5-mm width, which was considered the best, the intima-media thickness was mean 646 μm (SD 66) for men and 613 μm (SD 68) for women. The systematic difference was −5 μm and the random difference was 31 μm. The CV was 4.9%. The study indicates that the reproducibility is sufficient for in vivo studies when the width of the region-of-interest is 1.0 mm or wider.
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| 23. |
- Cinthio, Magnus, et al.
(author)
-
Estimation of arterial pulse wave velocity with a new improved tissue Doppler method
- 2001
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In: 2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 0780372115 ; , s. 188-191
-
Conference paper (other academic/artistic)abstract
- The mechanical properties of the large arteries are important determinants in the circulation physiology. Quantities associated with vessel wall elasticity are of particular interest since they offer a possibility to separate diseased arteries from healthy. Pulse wave velocity (PWV) is a local measure of the arterial wall elasticity. This paper describes a new improved method for non-invasive local PWV estimation. The PWV estimation is based on arterial wall movements, which is detected by Tissue Doppler Imaging (TDI), a color Doppler optimized for low velocities. The TDI facility allows the artery to be measured at several positions simultaneously, which improves the PWV estimation considerably. The method is validated with respect to operator repeatability and operator reproducibility in a limited clinical study.
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| 24. |
- Cinthio, Magnus, et al.
(author)
-
Evaluation of an algorithm for arterial lumen diameter measurements by means of ultrasound.
- 2010
-
In: Medical & Biological Engineering & Computing. - : Springer Science and Business Media LLC. - 0140-0118 .- 1741-0444. ; 48, s. 1133-1140
-
Journal article (peer-reviewed)abstract
- We have developed an algorithm for arterial luminal diameter measurement by means of ultrasound and evaluated the algorithm on agar vessel phantoms and in vivo. The algorithm utilises relative threshold detection on the inner slopes of the arterial walls before the resolution is improved by solving the equation of a straight line between the samples around the threshold value. Further, correction distances added to compensate for the underestimation when using the inner slopes were found to be 304 mum for the near wall and 415 mum for the far wall. The measured mean diameters of ten consecutive images of 3-, 6- and 9-mm phantoms were 3,006 mum (SD 4), 5,918 mum (SD 1) and 8,936 mum (SD 2), respectively. The mean differences between the images were 0.19, 0.04 and 0.37 mum, respectively. In vivo, the intra- and inter-observer variabilities were -64 mum (2SD 358) and -57 mum (2SD 366), respectively.
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| 25. |
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| 26. |
- Cinthio, Magnus, et al.
(author)
-
Individuell betygsättning av grupparbeten inom högre utbildning
- 2016
-
In: 9:e Pedagogiska Inspirationskonferensen 2016. - 2003-3761 .- 2003-377X. ; 9
-
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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| 27. |
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| 28. |
- Cinthio, Magnus, et al.
(author)
-
Instruktioner för laborationsrapportskrivande
- 2008
-
In: [Host publication title missing].
-
Conference paper (peer-reviewed)abstract
- I denna undersökning studeras hur laborations- rapporter vid LTH motiveras som pedagogiskt moment, hur skrivinstruktionerna är relaterade till lärandemomentet, och om detta kan förbättras. Det visar sig att de flesta instruktioner endast mycket kortfattat motiverar varför laborationsrapporter skrivs även om kursansvariga har ambitiösa mål med momentet. I skrivinstruktionerna finns ofta fler dispositions- och formaliainstruktioner än sådana som syftar till reflektion, till att förbättra skrivandet eller som uppmuntrar till vetenskapligt tänkande. Ett intressant angreppssätt, LabWrite, används vid North Carolina State University at Rayleigh, USA, där laboration och rapport används som ett sätt för studenten att också lära sig ett vetenskapligt förhållningssätt. LabWrite är intressant, men som första steg anser vi att instruktionen kan göras tydligare. Ett förslag är att dela upp den i tre distinkta delar; instruktioner som syftar till kritiskt tänkande, instruktioner om disposition och layout och slutligen instruktioner av teknisk karaktär.
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| 29. |
- Cinthio, Magnus, et al.
(author)
-
Intra-Observer Variability of Longitudinal Movement and Intramural Shear Strain Measurements of the Arterial Wall using Ultrasound Non-Invasively in vivo
- 2010
-
In: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629. ; 36:5, s. 697-704
-
Journal article (peer-reviewed)abstract
- Using a recently developed high-resolution noninvasive ultrasonic method, we recently demonstrated that the intima-media complex of the common carotid artery show a bidirectional multiphasic longitudinal displacement of the same magnitude as the diameter change during the cardiac cycle. The longitudinal movement of the adventitial region was smaller, thus, we identified shear strain and, thus, shear stress, within the arterial wall. The aim of this study was to evaluate the intra-observer variability of measurement of the longitudinal displacement of the intima-media complex and the intramural shear strain of the common carotid artery in vivo using the new ultrasonic method. The evaluation was carried out by comparing two consecutive measurements on the common carotid artery of 20 healthy human subjects. According to the method of Bland Altman, we show that the systematic and random differences for the different phases of movement are acceptable in comparison to the measured displacement and no significant differences between the two measurements could be detected (p > 0.05 for all measured parameters). The coefficient of variation (CV) for measurement of the different phases of movement was ≤16%, including short-term physiologic variations. The higher variability in the measurement of the intramural shear strain (CV = 24%) has several explanations, which are discussed. In conclusion, this study shows that the present first ultrasonic method for high-resolution measurement of the longitudinal movement of the arterial wall is reliable and satisfactory for the further research of the longitudinal movement of the arterial wall in vivo. Further studies on the longitudinal movement of the arterial wall are important for developing an improved understanding of the physiology and the pathophysiology of the cardiovascular system.
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| 30. |
- Cinthio, Magnus, et al.
(author)
-
It is possible to resolve micrometer movements in B-mode images
- 2012
-
In: 2012 IEEE International Ultrasonics Symposium (IUS). ; , s. 2536-2539
-
Conference paper (peer-reviewed)abstract
- We have proposed an echo localization estimator which theoretically gives infinite resolution in the axial direction in ultrasonic B-mode images during 1) echo structure tracking and 2) distance measurements of distinct echoes. The performance of the estimator was evaluated using a HDI5000 (Philips Medical Systems, Bothell, WA, USA) with a 35 mm 5-12 MHz linear array transducer. The resulting pixel size in the B-mode image was 100 mu m. The controlled setup consisted of a small water container lined with ultrasound absorber carpet and placed on a micrometer table, a triangulation laser (M5L/2, MEL Mikroelektronik GmbH, Eching, Germany) connected to a high-performance digital multimeter HP 34401A (Agilent Technologies, USA) and a thermometer TESTO 925 (Testo AG, Germany). In each of the three measurement series the micrometer table was moved approximately 15 mu m in 10-12 steps. The echo localization estimator succeeded to resolve the minute movement (< 20 mu m) with high agreement with the reference method in all three series. The correlation was (R>0.998; p <10-e38; 0.86
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| 31. |
- Cinthio, Magnus, et al.
(author)
-
Longitudinal Movement of the Common Carotid Artery Wall : New Information on Cardiovascular Aging
- 2018
-
In: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629 .- 1879-291X. ; 44:11, s. 2283-2295
-
Journal article (peer-reviewed)abstract
- Putative changes in the multiphasic pattern of longitudinal movement of the common carotid artery wall in the normal aging process are unknown. The aim of this study was to explore the phases, and resulting patterns, of the longitudinal movement of the intima–media complex of the human common carotid artery with respect to age and gender. One hundred thirty-five healthy non-smoking patients of different ages were investigated using in-house-developed ultrasound methods. The patterns of longitudinal movement seen in middle-aged and older patients were markedly different from those commonly seen in young patients, including the appearance of two additional phases of motion and, thus, new complex patterns. The displacement and maximum velocity of one of the phases, occurring at the time of aortic valve closure, increased quadratically with age in both men and women.
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| 32. |
- Cinthio, Magnus, et al.
(author)
-
Longitudinal movements and resulting shear strain of the arterial wall
- 2006
-
In: American Journal of Physiology: Heart and Circulatory Physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 291:1, s. 394-402
-
Journal article (peer-reviewed)abstract
- There has been little interest in the longitudinal movement of the arterial wall. It has been assumed that this movement is negligible compared with the diameter change. Using a new high-resolution noninvasive ultrasonic method, we measured longitudinal movements and diameter change of the common carotid artery of 10 healthy humans. During the cardiac cycle, a distinct bidirectional longitudinal movement of the intima-media complex could be observed in all the subjects. An antegrade longitudinal movement, i.e., in the direction of blood flow, in early systole [ 0.39 mm ( SD 0.26)] was followed by a retrograde longitudinal movement, i.e., in the direction opposite blood flow [ -0.52 mm ( SD 0.27)], later in systole and a second antegrade longitudinal movement [ 0.41 mm ( SD 0.33)] in diastole. The corresponding diameter change was 0.65 mm ( SD 0.19). The adventitial region showed the same basic pattern of longitudinal movement; however, the magnitude of the movements was smaller than that of the intimamedia complex, thereby introducing shear strain and, thus, shear stress within the wall [ maximum shear strain between the intima-media complex and the adventitial region was 0.36 rad ( SD 0.26). These phenomena have not previously been described. Measurements were also performed on the abdominal aorta ( n = 3) and brachial ( n = 3) and popliteal ( n = 3) arteries. Our new information seems to be of fundamental importance for further study and evaluation of vascular biology and hemodynamics and, thus, for study of atherosclerosis and vascular diseases.
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| 33. |
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| 34. |
- Cinthio, Magnus, et al.
(author)
-
Minute roughness measurement using phase tracking for arterial wall diagnosis non-invasively in vivo
- 2007
-
In: Ultrasonics Symposium, 2007. IEEE, vols 1-6. - 1051-0117. ; , s. 997-1000
-
Conference paper (peer-reviewed)abstract
- Early diagnosis of atherosclerosis is essential as many of the risk factors are life-style dependent. We suggest a new method to measure minute roughness of the size of micrometers of the arterial wall. The method was evaluated using three silicone phantoms sized 13 fun, 23 itm and 33 pm, respectively. The mean of the measured heights of the phantoms were 8.1 mu m (SD 0.0), 23.3 mu m (SD 0.2) and 29.6 mu m (SD 0.1) in the forward direction, and 7.7 mu m (SI) 0.0), 21.9 mu m (SI) 0.2) and 27.3 mu m (SI) 3.6) In the backward direction, respectively. The phantom study shows very promising result and encourages to further evaluation and in vivo Investigations.
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| 35. |
- Cinthio, Magnus, et al.
(author)
-
New Approaches in Arterial Characterisation
- 2008
-
In: Proceedings of 11th International Symposium on Advanced Biomedical Ultrasound (Invited). ; , s. 3-8
-
Conference paper (other academic/artistic)abstract
- —The aim of this paper is to briefly present the historyand the status of the arterial characterization of today as wellas summarize our work on two new approaches in arterialcharacterization – measurements of the longitudinal movementand the minute roughness of the arterial wall.
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| 36. |
- Cinthio, Magnus, et al.
(author)
-
New improved and modified method for measurements of arterial wall movements in longitudinal and radial directions
- 2005
-
In: Medical physics : proceedings of the jointly held congresses ICMP 2005, 14th International Conference of the Medical Physics of the International Organization for Medical Physics (IOMP), the European Federation of Organisations in Medical Physics (EFOMP) and the German Society of Medical Physics (DGMP) [and] BMT 2005, 39th annual congress of the German Society for Biomedical Engineering (DGBMT) ; 14th - 17th September 2005, Nuremberg, Germany. ; 50, s. 869-870
-
Conference paper (other academic/artistic)
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| 37. |
- Cinthio, Magnus, et al.
(author)
-
New improved method for 2D arterial wall movement measurements
- 2005
-
In: Proceedings of the International Federation for Medical & Biomedical Engineering. 13th Nordic Baltic Conference on Biomedical Engineering and Medical Physics. - 9173059102 ; , s. 117-118
-
Conference paper (peer-reviewed)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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| 38. |
- Cinthio, Magnus, et al.
(author)
-
New non-invasive method for intima-media thickness and intima-media compression measurements
- 2005
-
In: Proceedings - IEEE Ultrasonics Symposium. - 1051-0117. - 0780393821 ; 1, s. 389-392
-
Conference paper (peer-reviewed)abstract
- Intim a-media thickness (IMT) is considered as a valuable marker of early atherosclerosis. We suggest a new algorithm for simultaneous measurements of absolute diameter at diastole, distension (diameter change), IMT at diastole and the intima-media compression (IMC) with a new fast, robust, high-resolution, and automatic algorithm utilizing the ultrasonic gray-scale information. The new algorithm is evaluated in a limited in vivo study on the common carotid artery of 5 healthy volunteers. The standard deviation within an investigation was (8 ± 4 μm; range 4-14 μm) during IMC measurements, (8 ± 5 μm; range 4-16 μm) during the measurements of the IMT at diastole, (30 ±36 μm; range 6-92 μm) during the distension measurements and (48 ±49 μm; range 15-134 μm) during the measurements of the lumen diameter at diastole. The evaluation shows that the algorithm is fast and that the reproducibility and resolution are more than sufficient for in vivo studies. © 2005 IEEE.
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| 39. |
- Cinthio, Magnus, et al.
(author)
-
Non-invasive measurements of longitudinal strain of the arterial wall
- 2007
-
In: Ultrasonics Symposium, 2007. IEEE, vols 1-6. - 1051-0117. - 9781424413843 ; , s. 570-572
-
Conference paper (peer-reviewed)abstract
- We have recently shown that there is a previous unknown longitudinal movement present in the arterial wall. The aim is now to investigate whether the longitudinal movement is associated with longitudinal strain of the arterial wall. The objective of this paper was to describe a new non-invasive ultrasonic technique that measures the longitudinal strain of arteries in human in-vivo. Results indicate that a longitudinal strain is present in the common carotid artery.
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| 40. |
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| 41. |
- Cinthio, Magnus
(author)
-
Ultrasonic Methods for 2D Arterial Wall Movement Measurements
- 2004
-
Doctoral thesis (other academic/artistic)abstract
- Cardiovascular diseases constitute the major cause of morbidity and mortality in the Western World. To increase our knowledge of cardiovascular diseases, it is important to find methods, preferably non-invasive ones, to study very early manifestations of vascular disease. Changes in the mechanical properties of the arteries can be an early manifestation of vascular disease. Further, changes in the mechanical properties of arteries can have important haemodynamic consequences, and are being increasingly recognised as important factors in cardiovascular morbidity and mortality. To obtain a measure of the mechanical properties in the arteries, arterial characterisation is performed. This thesis consists of seven papers concerning arterial characterisation and new ultrasonic methods for arterial characterisation. The first paper is an introduction and an overview of the area around vessel characterisation. Papers II and III describe and evaluate a new method for local non-invasive pulse-wave velocity (PWV) estimation. The PWV estimation was based on arterial-wall movement, which was detected by Tissue Doppler Imaging (TDI). The method was evaluated and optimised on an in vitro set-up and validated in vivo with respect to repeatability and reproducibility in a clinical study. In the evaluation, it was shown that system parameters have a significant effect on the PWV variance, whereas the PWV mean remains unchanged. Furthermore, it was established that high temporal resolution is the most vital parameter for minimising the PWV variance. The longitudinal movement of blood-vessel walls has so far gained little or no attention, as it has been presumed that these movements are of a negligible magnitude. The fourth paper presents results from the first in vivo study with a new unique ultrasonic method for measurement of both the radial and the longitudinal movement of the arterial wall, and it is shown that the magnitude of the longitudinal movement is not negligible, that movement due to breathing affects the recording of arterial longitudinal movement in common carotid artery, and that there was a shear stress present within the arterial wall in one volunteer. The new unique ultrasonic method is evaluated in vitro in paper V, and accuracy, reproducibility, and resolution were all considerably better than the resolution of the applied ultrasound scanner. The sixth paper describes a new method for arterial luminal diameter measurement with ultrasound. Features of the new method are its robustness, fastness, and resolution. The method was calibrated on a vessel phantom and was evaluated in vivo with respect to accuracy and reproducibility, which both were considerably better than the resolution of the applied ultrasound scanner. The seventh paper presents results from an in vivo study where a new digitised ultrasonic method called Elastart, which measures arterial lumen diameter at diastole and arterial distension with tissue Doppler, is compared with a golden standard method. The evaluation of the method in vivo against a golden standard showed that no difference in reproducibility between the two systems could be found. However, measurements of the arterial lumen diameter showed a slight underestimation of the Elastart system compared with the golden standard.
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| 42. |
- Dahlén, Elsa M, et al.
(author)
-
Is there an underestimation of intima-media thickness based on M-mode ultrasound technique in the abdominal aorta?
- 2012
-
In: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:1, s. 1-4
-
Journal article (peer-reviewed)abstract
- Measuring intima-media thickness (IMT) in the common carotid artery (CCA) is a valuable resource for the evaluation of subclinical atherosclerosis. The main objective of this study was to explore whether a B-mode ultrasound technique, Philips ATL, and an M-mode ultrasound technique, Wall Track System (WTS), show interchangeable results when measured in CCA and the abdominal aorta (AA). A total of 24 healthy, young subjects were examined. IMT and lumen diameter (LD) of the AA and the CCA were measured twice by two skilled ultrasonographers with two different ultrasound equipment B-mode: (Philips, ATL and M-mode: WTS).The intra-observer variability of IMT in CCA and AA using B-mode showed a coefficient of variation 8% and 9%, and with M-mode 11% and 15%, respectively. Interobserver variability of IMT in CCA and AA using B-mode was 6% and 12%, and with M-mode 11% and 18%, respectively. CCA IMT was 0·53 ± 0·07 and 0·53 ± 0·09 mm using B-mode and M-mode, respectively. However, in AA, IMT was 0·61 ± 0·5 and 0·54 ± 0·10 mm using B-mode and M-mode, respectively. Thus, AA IMT was 11·5% thicker using B-mode (P<0·01). We received adequate IMT readings from the carotid artery as well as the AA using two commonly used B-mode and M-mode techniques. B-mode technique seems to show less variability, especially in the AA. More importantly, the two techniques measured different IMT thickness in the aorta, emphasizing the importance of using similar technique when comparing the impact of absolute values of IMT on cardiovascular disease.
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| 43. |
- Dahlstrand, Ulf, et al.
(author)
-
Photoacoustic imaging for three-dimensional visualization and delineation of basal cell carcinoma in patients
- 2020
-
In: Photoacoustics. - : Elsevier BV. - 2213-5979. ; 18
-
Journal article (peer-reviewed)abstract
- Background: Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used to determine the borders of basal cell carcinomas (BCC) preoperatively in order to reduce the need for repeated surgery.Methods: Two- and three-dimensional PA images were obtained by scanning BCCs using 59 wavelengths in the range 680-970 nm. Spectral unmixing was performed to visualize the tumor tissue distribution. Spectral signatures from 38 BCCs and healthy tissue were compared ex vivo.Results and discussion: The PA spectra could be used to differentiate between BCC and healthy tissue ex vivo (p < 0.05). Spectral unmixing provided visualization of the overall architecture of the lesion and its border.Conclusion: PA imaging can be used to differentiate between BCC and healthy tissue and can potentially be used to delineate tumors prior to surgical excision.
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| 44. |
- Dahlstrand, Ulf, et al.
(author)
-
Photoacoustic Imaging of Enucleated Eyes from Patients with Uveal Melanoma can Reveal Extrascleral Growth
- 2021
-
In: Open Ophthalmology Journal. - : Bentham Science Publishers Ltd.. - 1874-3641. ; 15:1, s. 270-276
-
Journal article (peer-reviewed)abstract
- Background:Uveal melanoma is treated by either enucleation (removal of the eye) or local eye-sparing therapies, depending on tumor size and whether there are signs of extrascleral growth. Photoacoustic (PA) imaging is a novel imaging modality that provides high-resolution images of the molecular composition of tissues.Objective:In this study, the feasibility of PA imaging for uveal melanomas and detection of extrascleral growth was explored.Methods:Seven enucleated human eyes with uveal melanomas were examined using PA imaging. The spectral signatures of the melanomas and the layers of the normal eyewall were characterized using 59 excitation wavelengths from 680 to 970 nm.Results:Significant differences were seen between the spectra obtained from melanoma and the healthy eyewall. Using spectral unmixing, melanin, hemoglobin and collagen could be mapped out, showing the architecture of the tumor in relation to the eyewall. This allowed visualization of regions where the tumor extended into the extrascleral space.Conclusion:PA imaging appears to have the potential to aid in assessing uveal melanomas and as a diagnostic tool for the detection of extrascleral growth.
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| 45. |
- Dahlstrand, Ulf, et al.
(author)
-
Spectral Signatures in the Different Layers of the Human Eyelid by Photoacoustic Imaging
- 2019
-
In: Lasers in Surgery and Medicine. - : Wiley. - 0196-8092 .- 1096-9101.
-
Journal article (peer-reviewed)abstract
- BACKGROUND AND OBJECTIVES: The eyelids are susceptible to a number of skin cancers, which are challenging to excise radically without sacrificing excessive healthy tissue. Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used for intraoperative micrographic control of the surgical margins of eyelid tumors. In this study, non-cancerous human eyelid tissue was characterized using PA as a first step in the development of this technique.STUDY DESIGN/MATERIALS AND METHODS: Twelve full-thickness samples from nine patients were analyzed ex vivo using PA imaging. Two-dimensional PA images were acquired using 59 wavelengths in the range of 680-970 nm to obtain the spectral signatures of the skin, orbicularis oculi muscle, and the tarsal plate. Three-dimensional images were obtained by scanning the tissues using a linear stepping motor. Spectral unmixing was performed to visualize the chromophore distribution.RESULTS: The resulting PA spectra could be used to differentiate between the orbicularis oculi muscle and the other two structures (P < 0.05). The signals from the skin and the tarsal plate were more similar in appearance, probably due to similarities in their molecular composition. Spectral unmixing provided a clear visualization of the overall architecture of the eyelids.CONCLUSIONS: PA imaging can be used to differentiate between the orbicularis oculi muscle and the eyelid skin and tarsal plate. The main structures of human eyelids could be visualized in three dimensions using PA imaging. This technique could potentially be used to examine eyelid tumors intraoperatively in the future. However, further studies on tumors in vivo are needed before considering such clinical use. Lasers Surg Med. © 2019 Wiley Periodicals, Inc.
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| 46. |
- Erlöv, Tobias, et al.
(author)
-
A Computer Program for Assessing Histoanatomical Morphometrics in Ultra-High-Frequency Ultrasound Images of the Bowel Wall in Children : Development and Inter-Observer Variability
- 2023
-
In: Diagnostics. - 2075-4418. ; 13:17
-
Journal article (peer-reviewed)abstract
- Ultra-high-frequency ultrasound (UHFUS) has a reported potential to differentiate between aganglionic and ganglionic bowel wall, referred to as histoanatomical differences. A good correlation between histoanatomy and UHFUS of the bowel wall has been proven. In order to perform more precise and objective histoanatomical morphometrics, the main research objective of this study was to develop a computer program for the assessment and automatic calculation of the histoanatomical morphometrics of the bowel wall in UHFUS images. A computer program for UHFUS diagnostics was developed and presented. A user interface was developed in close collaboration between pediatric surgeons and biomedical engineers, to enable interaction with UHFUS images. Images from ex vivo bowel wall samples of 23 children with recto-sigmoid Hirschsprung’s disease were inserted. The program calculated both thickness and amplitudes (image whiteness) within different histoanatomical bowel wall layers. Two observers assessed the images using the program and the inter-observer variability was evaluated. There was an excellent agreement between observers, with an intraclass correlation coefficient range of 0.970–0.998. Bland–Altman plots showed flat and narrow distributions. The mean differences ranged from 0.005 to 0.016 mm in thickness and 0 to 0.7 in amplitude units, corresponding to 1.1–3.6% and 0.0–0.8% from the overall mean. The computer program enables and ensures objective, accurate and time-efficient measurements of histoanatomical thicknesses and amplitudes in UHFUS images of the bowel wall. The program can potentially be used for several bowel wall conditions, accelerating research within UHFUS diagnostics.
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| 47. |
- Erlöv, Tobias, et al.
(author)
-
A fast 2D tissue motion estimator based on the phase of the intensity enables visualization of the propagation of the longitudinal movement in the carotid artery wall
- 2013
-
In: 2013 IEEE International Ultrasonics Symposium (IUS). - 9781467356855 ; , s. 1761-1764
-
Conference paper (peer-reviewed)abstract
- A fast 2D motion estimator has been developed and evaluated. The method does not utilize block-matching or iterative solutions and is thus more computationally efficient and suitable for real-time motion estimation over the entire image. The method has been evaluated on 1) phantom measurements and 2) in vivo on the carotid artery wall of 17 subjects, where measurements of the longitudinal displacement of the intima-media complex were compared to our previously validated method. The mean error of the phantom measurements was 2.0 +/- 3.3% (velocities between 2-15 mm/s; approx. 60 million estimations). In the in vivo measurements the mean difference (validated-proposed) was 18 +/- 44 mu m. Further the method has enabled visualization of the propagation of the longitudinal movement in the carotid artery wall. Several different phases of the longitudinal propagation, which seem to be connected to the multi-phasic pattern of the longitudinal movement, can be seen. All phases of the longitudinal propagation seem to originate from the direction of the heart.
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| 48. |
- Erlöv, Tobias, et al.
(author)
-
A method for measuring the variation of intima-media thickness during the entire cardiac cycle using B-Mode images
- 2011
-
In: 2011 IEEE International Ultrasonics Symposium (IUS). - 9781457712531 ; , s. 2126-2129
-
Conference paper (peer-reviewed)abstract
- Increased intima-media thickness (IMT) has been shown to predict cardiovascular risk, and measurement of intima-media thickness has been extensively used in medical research since the mid-1990s. IMT is conventionally measured by manual tracing, however this method is very time-consuming and suffers from large inter-observer variability. Numerous methods, both semi-automatic and fully-automatic, have been suggested to limit the influence of the observer. However, most methods only report one value per cardiac cycle instead of the variation of IMT over time. We propose a new method that measures the variation of IMT during the entire cardiac cycle. The method tracks spatial variations with compensation for both longitudinal movement and angle variations. This enables detection of positions where an inaccurate measurement of IMT has occurred. These can then be removed from the calculations in order to maximize the accuracy. The method was evaluated in vivo on 20 healthy individuals (mean age 38 years, range 25-57). The overall IMT in diastole (IMTdia) was 717+/-69 mu m and the intima-media compression (IMC) was 66+/-21 mu m which corresponds to a 9.2+/-2.6% maximal compression of the arterial wall during a cardiac cycle. The CV was 3.5% for IMTdia and 9.9% for IMC. Extending traditional IMT measurement to include also the variation of IMT during a cardiac cycle may improve the individual risk classification for cardiovascular diseases.
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| 49. |
- Erlöv, Tobias, et al.
(author)
-
A Method to Measure Shear Strain with High Spatial Resolution in the Arterial Wall Non-Invasively in vivo by Tracking Zero-Crossings of B-Mode Intensity Gradients
- 2010
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In: Proceedings - IEEE Ultrasonics Symposium. - 9781457703812 ; , s. 491-494
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Conference paper (peer-reviewed)abstract
- We have previously shown that there is a distinct longitudinal movement of the arterial wall during a cardiac cycle. This movement is larger in the intima-media region than in the adventitial region which introduces a substantial shear strain within the arterial wall. Our previously developed echo-tracking algorithm measured this shear strain by tracking two separate echoes, one in the intima-media region and one in the adventitia region and thus only a linear distribution was evaluated. The objective of this study was to suggest and evaluate a new improved method which can measure the intramural shear strain with higher spatial resolution and thereby provide more information on this new and rather unknown phenomenon. The mean maximum shear strain was 0.82 radians with a standard deviation of 0.17 radians and a CV-value of 14.2%. The total mean difference in measured longitudinal movement between the new and previous method was 10μm with a standard deviation of 90μm and a CV-value of 12.8%. The spatial distribution of the intramural shear strain seems to be very non-linear with a large amount of shear strain occurring in a small section around the transition between the media and adventitia layers.
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- Erlöv, Tobias, et al.
(author)
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A robust and fast method for arterial lumen diameter and intima-media thickness measurements
- 2012
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In: 2012 IEEE International Ultrasonics Symposium (IUS). - 9781467345613 - 9781467345620 ; , s. 1678-1681
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Conference paper (peer-reviewed)abstract
- Lumen diameter, distension and intima-media thickness (IMT) in human arteries are important parameters in cardiovascular research. The signal reflected from the arterial wall strongly depends on the ultrasound scanner and settings. The signal also varies with age and health of the subject. A general method insensitive with respect to the subject and the scanner would be of great help. We have developed a novel and robust method for ARTerIal Characterization (ARTIC), suitable for real-time in vivo measurements of diameter, distension and IMT using B-Mode images. The aim of this study was to evaluate ARTIC on different subjects and scanners. ARTIC was evaluated in vivo in different groups of subjects using two scanners, HDI5000 (Philips Medical Systems, Bothell, WA, USA) and ULA-OP (University of Florence, Italy). First, a comparison was made against a previous method validated on phantoms. Then measurements of young (healthy) and old (healthy and unhealthy) subjects were evaluated for both scanners. Finally, a comparison between scanners was made. The evaluation of different subjects shows a coefficient of variation (CV) ranging from 1.4-2.0% for diameter, 4.3-8.8% for distension and 3.6-6.6% for IMT.
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