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  • 51.
    Chaabane, Wiem
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Health Sciences. Tunis University, Tunisia.
    Cieślar-Pobuda, Artur
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Health Sciences. Silesian University of Technology, Gliwice, Poland.
    El-Gazzah, Mohamed
    Tunis University, Tunisia.
    Jain, Mayur V.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Health Sciences.
    Rzeszowska-Wolny, Joanna
    Silesian University of Technology, Gliwice, Poland.
    Rafat, Mehrdad
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Health Sciences.
    Stetefeld, Joerg
    University of Manitoba, Winnipeg, Canada.
    Ghavami, Saeid
    University of Manitoba, Winnipeg, Canada.
    Los, Marek
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Health Sciences. Pomeranian Medical University, Szczecin, Poland.
    Human-Gyrovirus-Apoptin Triggers Mitochondrial Death Pathway—Nur77 is Required for Apoptosis Triggering: 2014In: Neoplasia, ISSN 1522-8002, E-ISSN 1476-5586, Vol. 16, no 9, p. 679-693Article in journal (Refereed)
    Abstract [en]

    The human gyrovirus derived protein Apoptin (HGV-Apoptin) a homologue of the chicken anemia virus Apoptin (CAV-Apoptin), a protein with high cancer cells selective toxicity, trigger apoptosis selectively in cancer cells. In this paper, we show that HGV-Apoptin acts independently from the death receptor pathway as it induces apoptosis in similar rates in Jurkat cells deficient in either FADD-function or caspase-8 (key players of the extrinsic pathway) and their parental clones. HGV-Apoptin induces apoptosis via the activation of the mitochondrial intrinsic pathway. It induces both mitochondrial inner and outer membrane permebilization, characterized by the loss of the mitochondrial potential and the release into cytoplasm of the pro-apoptotic molecules including apoptosis inducing factor (AIF) and cytochrome c. HGV-Apoptin acts via the apoptosome, as lack of expression of APAF1 in murine embryonic fibroblast strongly protected the cells from HGV-Apoptin-induced apoptosis. Moreover, QVD-oph a broad-spectrum caspase inhibitor delayed HGV-Apoptin-induced death. On the other hand, overexpression of the anti-apoptotic BCL-XL confers resistance to HGV-Apoptin induced cell death. In contrast, cells that lack the expression of the pro-apoptotic BAX and BAK are protected from HGV-Apoptin induced apoptosis. Furthermore, HGV-Apoptin acts independently from p53 signal but triggers the cytoplasmic translocation of Nur77. Taking together this data indicate that HGV-Apoptin acts through the mitochondrial pathway, in a caspase-dependent manner but independently from the death receptor pathway.

  • 52. Clancy, N.
    et al.
    Leahy, MJ.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Anderson, Chris
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Non-invasive assessment of the mechanical properties of human skin - investigation of effective age using an optical method2006In: Royal Academy of Medicine in Ireland, Section of Biomedical Sciences, University of Limerick, Summer Meeting,2006, 2006Conference paper (Refereed)
  • 53.
    Clancy, Neil T.
    et al.
    Department of Physics, University of Limerick, Ireland.
    Leahy, Martin J.
    Department of Physics, University of Limerick, Ireland.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson, Chris
    Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Analysis of skin recovery from mechanical indentation using diffuse lighting and digital imaging2007In: Diffuse Optical Imaging of Tissue / [ed] Brian W. Pogue; Rinaldo Cubeddu, SPIE - International Society for Optical Engineering, 2007, p. 66291G-1-66291G-10Conference paper (Other academic)
    Abstract [en]

    Skin behaves as a viscoelastic material, having mechanical properties composed of elastic and fluid components. Upon indentation, the fibres are stretched and fluid displaced from the compressed region. The rate of recovery from this imprint is therefore dependent on the hydration and elasticity of the skin. A reliable measurement could be applied to the assessment of clinical conditions such as oedema, rare genetic disorders such as cutis laxa  and the evaluation of the 'effective age' of skin in vivo . This paper describes a new approach to the non-invasive indentation technique and a novel method of analysis. A method is proposed that tracks the skin's recovery optically from an initial strain made using a mechanical indentor, diffuse side-lighting and a CCD video-capture device. Using the blue colour plane of the image it is possible to examine the surface topography only, and track the decay of the imprint over time. Two algorithms are discussed for the extraction of information on the skin's displacement and are analysed in terms of reliability and reproducibility.

  • 54.
    Clancy, Neil T.
    et al.
    Department of Physics, University of Limerick, Ireland.
    Leahy, Martin J.
    Department of Physics, University of Limerick, Ireland.
    Nilsson, Gert E.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson, Chris
    Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Analysis of skin recovery from mechanical indentation using diffuse lighting and digital imaging. in Diffuse Optical Imaging of Tissue.2007In: Proceedings of SPIE - Diffuse Optical Imaging of Tissue / [ed] Brian W. Pogue, Rinaldo Cubeddu, Bellingham, WA, United States: SPIE - International Society for Optical Engineering, 2007, p. 66291G-1-66291G-10Conference paper (Refereed)
    Abstract [en]

    Skin behaves as a viscoelastic material, having mechanical properties composed of elastic and fluid components. Upon indentation, the fibres are stretched and fluid displaced from the compressed region. The rate of recovery from this imprint is therefore dependent on the hydration and elasticity of the skin. A reliable measurement could be applied to the assessment of clinical conditions such as oedema, rare genetic disorders such as cutis laxa and the evaluation of the 'effective age' of skin in vivo . This paper describes a new approach to the non-invasive indentation technique and a novel method of analysis. A method is proposed that tracks the skin's recovery optically from an initial strain made using a mechanical indentor, diffuse side-lighting and a CCD video-capture device. Using the blue colour plane of the image it is possible to examine the surface topography only, and track the decay of the imprint over time. Two algorithms are discussed for the extraction of information on the skin's displacement and are analysed in terms of reliability and reproducibility.

  • 55.
    Clancy, Neil T
    et al.
    University of London Imperial College of Science, Technology and Medicine.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson, Chris
    Linköping University, Department of Clinical and Experimental Medicine, Dermatology and Venerology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Leahy, Martin J
    University of Limerick.
    A new device for assessing changes in skin viscoelasticity using indentation and optical measurement2010In: SKIN RESEARCH AND TECHNOLOGY, ISSN 0909-752X, Vol. 16, no 2, p. 210-228Article in journal (Refereed)
    Abstract [en]

    Background/aims Skin is a viscoelastic material, comprised of fluidic and fibrous components. Changes in viscoelasticity can arise due to a number of conditions including dehydration, swelling (associated with injury or disease), impaired heart function, rehydration therapy, ageing, scarring, sun exposure and genetic conditions affecting connective tissue. Quantification of changes in skin viscoelasticity due to these processes is of great clinical interest in the fields of therapy monitoring, wound healing and disease screening. However, devices currently available to measure aspects of the mechanical properties of skin have limitations in ease-of-use, accessibility, and depth of measurement. This paper describes a new technique to follow changes in the viscoelasticity of the skin, using a novel approach to an indentation manoeuvre. The device is portable, low-cost and easy to use while at the same time providing rich information on the mechanical response of the skin. Methods The method proposed optically tracks the skins recovery from an initial strain, made with a novel linear indentor, using diffuse side-lighting and a CCD video camera. Upon indentation, the skins elastin fibres are stretched and fluid is displaced from the compressed region. When the indentor is removed, the rate of recovery of the skin from this imprint is therefore principally dependent on its hydration and elasticity. Using the blue colour plane of the image and polarisation filtering, it is possible to examine the surface topography only, and track the decay of the imprint over time. Results The decrease in size of the imprint over time (decay curve) recorded by the device is shown to agree with the theoretical predictions of an appropriate viscoelastic model of skin mechanical behaviour. The contributors to the response measured using the indentation device are fully characterised and evaluated using separate measurement techniques including high-frequency ultrasound, polarisation spectroscopy and optical coherence tomography. Conclusion The device developed is capable of tracking the viscoelastic response of skin to minimal indentation. The high precision achieved using low-cost materials means that the device could be a viable alternative to current technologies.

  • 56. Clancy, NT.
    et al.
    Leahy, MJ.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Non-invasive assessment of the mechanical properties of human skin - investigation of effective age using an optical method2006In: BioMed 2006,2006, 2006Conference paper (Refereed)
    Abstract [en]

      

  • 57. Clancy, NT.
    et al.
    Leahy, MJ.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Anderson, Chris
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Analysis of mechanical imprints in human skin using an optical technique. in Fission Impossible?2007In: IOPI Spring Weekend Meeting,2007, 2007Conference paper (Refereed)
  • 58.
    Colantonio, Sara
    et al.
    CNR, Italy.
    Germanese, Danila
    CNR, Italy.
    Moroni, Davide
    CNR, Italy.
    Giorgi, Daniela
    CNR, Italy.
    Pascali, Mariantonietta
    CNR, Italy.
    Righi, Marco
    CNR, Italy.
    Coppini, Giuseppe
    CNR, Italy.
    Aurora Morales, Maria
    CNR, Italy.
    Chiarugi, Franco
    FORTH, Greece.
    Pediaditis, Mattew
    FORTH, Greece.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Henriquez, Pedro
    University of Central Lancashire, England.
    Matuszewski, Bogdan
    University of Central Lancashire, England.
    Milanic, Matijia
    Norwegian University of Science and Technology, Norway.
    Randeberg, Lise
    Norwegian University of Science and Technology, Norway.
    SEMEOTICONS - READING THE FACE CODE OF CARDIO-METABOLIC RISK2015In: 2015 INTERNATIONAL WORKSHOP ON COMPUTATIONAL INTELLIGENCE FOR MULTIMEDIA UNDERSTANDING (IWCIM), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    What if you could discover your health status by looking at yourself in the mirror? Since November 2013, the EU FP7 Project SEMEOTICONS is working to make this possible. The Project is building a multi-sensory device, having the form of a conventional mirror, able to read the semeiotic code of the face and detect possible evidence of the onset of cardio-metabolic diseases. The device, called Wize Mirror, integrates unobtrusive imaging sensors used to capture videos, images and 3D scans of the face. These are processed to assess the risk of a cardio-metabolic disease and thereby suggest possible strategies to prevent its onset.

  • 59.
    Cubo, Ruben
    et al.
    Uppsala University, Sweden.
    Medvedev, Alexander
    Uppsala University, Sweden.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Model-Based Optimization of Individualized Deep Brain Stimulation Therapy2016In: IEEE DESIGN and TEST, ISSN 2168-2356, Vol. 33, no 4, p. 74-81Article in journal (Refereed)
    Abstract [en]

    n/a

  • 60.
    Cubo, Ruben
    et al.
    Uppsala University, Sweden.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Medtron Eindhoven Design Centre, Netherlands.
    Medvedev, Alexander
    Uppsala University, Sweden.
    Electric Field Modeling and Spatial Control in Deep Brain Stimulation2015In: 2015 54TH IEEE CONFERENCE ON DECISION AND CONTROL (CDC), IEEE , 2015, p. 3846-3851Conference paper (Refereed)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established treatment, in e.g. Parkinsons Disease, whose underlying biological mechanisms are unknown. In DBS, electrical stimulation is delivered through electrodes surgically implanted into certain regions of the brain of the patient. Mathematical models aiming at a better understanding of DBS and optimization of its therapeutical effect through the simulation of the electrical field propagating in the brain tissue have been developed in the past decade. The contribution of the present study is twofold: First, an analytical approximation of the electric field produced by an emitting contact is suggested and compared to the numerical solution given by a Finite Element Method (FEM) solver. Second, the optimal stimulation settings are evaluated by fitting the field distribution to a target one to control the spread of the stimulation. Optimization results are compared to those of a geometric approach, maximizing the intersection between the target and the activated volume in the brain tissue and reducing the stimulated area beyond said target. Both methods exhibit similar performance with respect to the optimal stimuli, with the electric field control approach being faster and more versatile.

  • 61.
    Cubo, Ruben
    et al.
    Uppsala University, Sweden.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Medvedev, Alexander
    Uppsala University, Sweden.
    Target coverage and selectivity in field steering brain stimulation2014In: 2014 36TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), Institute of Electrical and Electronics Engineers (IEEE), 2014, p. 522-525Conference paper (Refereed)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established treatment in Parkinsons Disease. The target area is defined based on the state and brain anatomy of the patient. The stimulation delivered via state-of-the-art DBS leads that are currently in clinical use is difficult to individualize to the patient particularities. Furthermore, the electric field generated by such a lead has a limited selectivity, resulting in stimulation of areas adjacent to the target and thus causing undesirable side effects. The goal of this study is, using actual clinical data, to compare in silico the stimulation performance of a symmetrical generic lead to a more versatile and adaptable one allowing, in particular, for asymmetric stimulation. The fraction of the volume of activated tissue in the target area and the fraction of the stimulation field that spreads beyond it are computed for a clinical data set of patients in order to quantify the lead performance. The obtained results suggest that using more versatile DBS leads might reduce the stimulation area beyond the target and thus lessen side effects for the same achieved therapeutical effect.

  • 62.
    Danielis, Alessandro
    et al.
    CNR, Italy.
    Giorgi, Daniela
    CNR, Italy.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Colantonio, Sara
    CNR, Italy.
    Salvetti, Ovidio
    CNR, Italy.
    Lip segmentation based on Lambertian shadings and morphological operators for hyper-spectral images2017In: Pattern Recognition, ISSN 0031-3203, E-ISSN 1873-5142, Vol. 63, p. 355-370Article in journal (Refereed)
    Abstract [en]

    Lip segmentation is a non-trivial task because the colour difference between the lip and the skin regions maybe not so noticeable sometimes. We propose an automatic lip segmentation technique for hyper-spectral images from an imaging prototype with medical applications. Contrarily to many other existing lip segmentation methods, we do not use colour space transformations to localise the lip area. As input image, we use for the first time a parametric blood concentration map computed by using narrow spectral bands. Our method mainly consists of three phases: (i) for each subject generate a subset of face images enhanced by different simulated Lambertian illuminations, then (ii) perform lip segmentation on each enhanced image by using constrained morphological operations, and finally (iii) extract features from Fourier-based modeled lip boundaries for selecting the lip candidate. Experiments for testing our approach are performed under controlled conditions on volunteers and on a public hyper-spectral dataset. Results show the effectiveness of the algorithm against low spectral range, moustache, and noise.

  • 63.
    Dembek, Till A.
    et al.
    Department of Neurology, University of Cologne, Cologne, Germany; Department of Stereotaxy and Functional Neurosurgery, University of Cologne, Cologne, Germany.
    Barbe, Michael T
    Department of Neurology, University of Cologne, Cologne, Germany.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Medtronic Neuromodulation, Medtronic Eindhoven Design Center, Eindhoven, The Netherlands.
    Hoevels, Mauritius
    Department of Stereotaxy and Functional Neurosurgery, University of Cologne, Cologne, Germany.
    Visser-Vandewalle, Veerle
    Department of Stereotaxy and Functional Neurosurgery, University of Cologne, Cologne, Germany.
    Fink, Gereon R
    Department of Neurology, University of Cologne, Cologne, Germany.
    Timmermann, Lars
    Department of Neurology, University of Cologne, Cologne, Germany.
    Probabilistic mapping of deep brain stimulation effects in essential tremor2017In: NeuroImage: Clinical, ISSN 0353-8842, E-ISSN 2213-1582, Vol. 13Article in journal (Refereed)
    Abstract [en]

    Objective

    To create probabilistic stimulation maps (PSMs) of deep brain stimulation (DBS) effects on tremor suppression and stimulation-induced side-effects in patients with essential tremor (ET).

    Method

    Monopolar reviews from 16 ET-patients which consisted of over 600 stimulation settings were used to create PSMs. A spherical model of the volume of neural activation was used to estimate the spatial extent of DBS for each setting. All data was pooled and voxel-wise statistical analysis as well as nonparametric permutation testing was used to confirm the validity of the PSMs.

    Results

    PSMs showed tremor suppression to be more pronounced by stimulation in the zona incerta (ZI) than in the ventral intermediate nucleus (VIM). Paresthesias and dizziness were most commonly associated with stimulation in the ZI and surrounding thalamic nuclei.

    Discussion

    Our results support the assumption, that the ZI might be a very effective target for tremor suppression. However stimulation inside the ZI and in its close vicinity was also related to the occurrence of stimulation-induced side-effects, so it remains unclear whether the VIM or the ZI is the overall better target. The study demonstrates the use of PSMs for target selection and evaluation. While their accuracy has to be carefully discussed, they can improve the understanding of DBS effects and can be of use for other DBS targets in the therapy of neurological or psychiatric disorders as well. Furthermore they provide a priori information about expected DBS effects in a certain region and might be helpful to clinicians in programming DBS devices in the future.

    Abbreviations: DBS, Deep brain stimulation; ET, Essential tremor; PSA, Posterior subthalamic area; PSM, Probabilistic stimulation map; VIM, Ventral intermediate nucleus; VNA, Volume of neural activation; ZI, Zona incerta

  • 64.
    Diczfalusy, Elin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Modeling and Simulation of Microdialysis in the Deep Brain Structures2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Microdialysis is a method for monitoring of the local biochemical environment in a region of interest. The method uses a catheter, mimicking the function of a blood capillary, to sample substances from the surrounding medium through diffusion. A recent application for microdialysis is the sampling of neuroactive substances in the deep brain, or basal ganglia, during deep brain stimulation (DBS) for patients with Parkinson’s disease. The basal ganglia consist of nuclei interconnected by chemical synapses, and it is hypothesized that the levels of neurotransmitter substances around the synapses are affected by DBS treatment. In order to relate the microdialysis data to their anatomical origin and to the effects of DBS, it is suitable to estimate the tissue volume which is sampled during a microdialysis experiment. In this thesis, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated and evaluated using the finite element method (FEM), to allow interpretation of biochemical data in relation to anatomical structures.

    A FEM model for simulation of the TVImax for a microdialysis catheter placed in grey brain matter was set up, using Fick’s law of diffusion. The model was used to investigate the impact of the analyte diffusion coefficient (D), the tissue tortuosity (λ) and the loss rate constant (k) on the size of the TVImax by regression analysis. Using relevant parameter intervals, the radius of the TVImax of a neurotransmitter was estimated to 0.85 ± 0.25 mm. A microdialysis experiment on calf brain tissue showed agreement with the regression model. A heterogeneous anisotropic FEM model based on diffusion tensor imaging (DTI) showed that the radius of the TVImax may vary by up to 0.5 mm as a consequence of local tissue properties, which was reasonable in relation to the 95% confidence interval from the regression estimation. The TVImax was simulated and patient-specifically visualized in relation to MRI images for four patients undergoing microdialysis in parallel to DBS. The size of the TVImax showed to be relevant in relation to the basal ganglia nuclei, and the obtained microdialysis data indicated that the biochemical response to DBS depends on the catheter position. The simulations of the TVImax were combined with patient-specific DBS electric field simulations, for further interpretation of the results in relation to the effects of DBS.

    In conclusion, simulations and visualizations of the TVImax allowed relating microdialysis data to its anatomical origin. Detailed knowledge about the parameters affecting the microdialysis sampling volume is valuable for the current application as well as other applications related to the migration of analytes in tissue.

    List of papers
    1. A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis
    Open this publication in new window or tab >>A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis
    Show others...
    2011 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 49, no 12, p. 1459-1469Article in journal (Refereed) Published
    Abstract [en]

    Microdialysis can be used in parallel to deep brain stimulation (DBS) to relate biochemical changes to the clinical outcome. The aim of the study was to use the finite element method to predict the tissue volume of influence (TVI(max)) and its cross-sectional radius (r (TVImax)) when using brain microdialysis, and visualize the TVI(max) in relation to patient anatomy. An equation based on Fick's law was used to simulate the TVI(max). Factorial design and regression analysis were used to investigate the impact of the diffusion coefficient, tortuosity and loss rate on the r (TVImax). A calf brain tissue experiment was performed to further evaluate these parameters. The model was implemented with pre-(MRI) and post-(CT) operative patient images for simulation of the TVI(max) for four patients undergoing microdialysis in parallel to DBS. Using physiologically relevant parameter values, the r (TVImax) for analytes with a diffusion coefficient D = 7.5 × 10(-6) cm(2)/s was estimated to 0.85 ± 0.25 mm. The simulations showed agreement with experimental data. Due to an implanted gold thread, the catheter positions were visible in the post-operative images. The TVI(max) was visualized for each catheter. The biochemical changes could thereby be related to their anatomical origin, facilitating interpretation of results.

    Place, publisher, year, edition, pages
    Springer Publishing Company, 2011
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-72911 (URN)10.1007/s11517-011-0841-0 (DOI)000297550600012 ()22081236 (PubMedID)
    Available from: 2011-12-09 Created: 2011-12-09 Last updated: 2018-01-12Bibliographically approved
    2. Simulations and visualizations for interpretation of brain microdialysis data during deep brain stimulation
    Open this publication in new window or tab >>Simulations and visualizations for interpretation of brain microdialysis data during deep brain stimulation
    Show others...
    2012 (English)In: IEEE Engineering in Medicine and Biology Society (EMBC), 2012, IEEE , 2012, p. 6438-6441Conference paper, Published paper (Refereed)
    Abstract [en]

    Microdialysis of the basal ganglia was used in parallel to deep brain stimulation (DBS) for patients with Parkinson’s disease. The aim of this study was to patientspecifically simulate and visualize the maximum tissue volume of influence (TVImax) for each microdialysis catheter and the electric field generated around each DBS electrode. The finite element method (FEM) was used for the simulations. The method allowed mapping of the anatomical origin of the microdialysis data and the electric stimulation for each patient. It  was seen that the sampling and stimulation targets differed among the patients, and the results will therefore be used in the future interpretation of the biochemical data.

    Place, publisher, year, edition, pages
    IEEE, 2012
    Series
    IEEE Engineering in Medicine and Biology Society Conference Proceedings, ISSN 1557-170X
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84275 (URN)10.1109/EMBC.2012.6347468 (DOI)000313296506155 ()23367403 (PubMedID)9781424441198 (ISBN)9781424441204 (ISBN)9781457717871 (ISBN)
    Conference
    34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2012), 28 August - 1 September 2012, San Diego, CA, USA
    Available from: 2012-10-03 Created: 2012-10-03 Last updated: 2018-01-12Bibliographically approved
    3. The effect of tissue heterogeneity and anisotropy on microdialysis of the deep brain
    Open this publication in new window or tab >>The effect of tissue heterogeneity and anisotropy on microdialysis of the deep brain
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Microdialysis of the basal ganglia was recently used to study changes of neurotransmitter levels in relation to deep brain stimulation (DBS). In order to estimate the anatomical origin of the microdialysis data, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated and visualized using the finite element method (FEM). In the current study the impact of brain heterogeneity and anisotropy on the TVImax was investigated, using diffusion tensor imaging (DTI) to create a second-order tensor model of the basal ganglia. The results were presented using descriptive statistics, indicating that the mean radius of the TVImax varied by up to 0.5 mm (n = 98444) for FEM simulations based on DTI compared to a homogeneous and isotropic reference model. The internal capsule and subthalamic area showed significantly higher anisotropy (p < 0.0001, n = 600) than the putamen and the globus pallidus, in accordance with theory. It was concluded that the size of the TVImax remained small enough to be relevant in relation to the anatomical structures of interest, and that local tissue properties should be accounted for when relating the microdialysis data to their anatomical targets.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84276 (URN)
    Available from: 2012-10-03 Created: 2012-10-03 Last updated: 2016-05-04Bibliographically approved
  • 65.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    A diffusion tensor-based finite element model of microdialysis in the deep brain2015In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, Vol. 18, no 2, p. 201-212Article in journal (Refereed)
    Abstract [en]

    Microdialysis of the basal ganglia was recently used to study neurotransmitter levels in relation to deep brain stimulation. In order to estimate the anatomical origin of the obtained data, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated using the finite element method. This study investigates the impact of brain heterogeneity and anisotropy on the TVImax using diffusion tensor imaging (DTI) to create a second-order tensor model of the basal ganglia. Descriptive statistics showed that the maximum migration distance for neurotransmitters varied by up to 55% (n = 98,444) for DTI-based simulations compared with an isotropic reference model, and the anisotropy differed between different targets in accordance with theory. The size of the TVImax was relevant in relation to the size of the anatomical structures of interest, and local tissue properties should be accounted for when relating microdialysis data to their anatomical targets.

  • 66.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    The effect of tissue heterogeneity and anisotropy on microdialysis of the deep brainManuscript (preprint) (Other academic)
    Abstract [en]

    Microdialysis of the basal ganglia was recently used to study changes of neurotransmitter levels in relation to deep brain stimulation (DBS). In order to estimate the anatomical origin of the microdialysis data, the maximum tissue volume of influence (TVImax) for a microdialysis catheter was simulated and visualized using the finite element method (FEM). In the current study the impact of brain heterogeneity and anisotropy on the TVImax was investigated, using diffusion tensor imaging (DTI) to create a second-order tensor model of the basal ganglia. The results were presented using descriptive statistics, indicating that the mean radius of the TVImax varied by up to 0.5 mm (n = 98444) for FEM simulations based on DTI compared to a homogeneous and isotropic reference model. The internal capsule and subthalamic area showed significantly higher anisotropy (p < 0.0001, n = 600) than the putamen and the globus pallidus, in accordance with theory. It was concluded that the size of the TVImax remained small enough to be relevant in relation to the anatomical structures of interest, and that local tissue properties should be accounted for when relating the microdialysis data to their anatomical targets.

  • 67.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Didzar, Nil
    Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Biochemical monitoring and simulation of the electric field during deep brain stimulation (oral)2010Conference paper (Other academic)
  • 68.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Dizdar (Dizdar Segrell), Nil
    Linköping University, Department of Clinical and Experimental Medicine, Neurology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Simulations and visualizations for interpretation of brain microdialysis data during deep brain stimulation2012In: IEEE Engineering in Medicine and Biology Society (EMBC), 2012, IEEE , 2012, p. 6438-6441Conference paper (Refereed)
    Abstract [en]

    Microdialysis of the basal ganglia was used in parallel to deep brain stimulation (DBS) for patients with Parkinson’s disease. The aim of this study was to patientspecifically simulate and visualize the maximum tissue volume of influence (TVImax) for each microdialysis catheter and the electric field generated around each DBS electrode. The finite element method (FEM) was used for the simulations. The method allowed mapping of the anatomical origin of the microdialysis data and the electric stimulation for each patient. It  was seen that the sampling and stimulation targets differed among the patients, and the results will therefore be used in the future interpretation of the biochemical data.

  • 69.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Simulation of Deep Brain Stimulation for Tourette's Syndrome (oral)2011Conference paper (Refereed)
  • 70.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Dizdar (Dizdar Segrell), Nil
    Linköping University, Department of Clinical and Experimental Medicine, Neurology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis2011In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 49, no 12, p. 1459-1469Article in journal (Refereed)
    Abstract [en]

    Microdialysis can be used in parallel to deep brain stimulation (DBS) to relate biochemical changes to the clinical outcome. The aim of the study was to use the finite element method to predict the tissue volume of influence (TVI(max)) and its cross-sectional radius (r (TVImax)) when using brain microdialysis, and visualize the TVI(max) in relation to patient anatomy. An equation based on Fick's law was used to simulate the TVI(max). Factorial design and regression analysis were used to investigate the impact of the diffusion coefficient, tortuosity and loss rate on the r (TVImax). A calf brain tissue experiment was performed to further evaluate these parameters. The model was implemented with pre-(MRI) and post-(CT) operative patient images for simulation of the TVI(max) for four patients undergoing microdialysis in parallel to DBS. Using physiologically relevant parameter values, the r (TVImax) for analytes with a diffusion coefficient D = 7.5 × 10(-6) cm(2)/s was estimated to 0.85 ± 0.25 mm. The simulations showed agreement with experimental data. Due to an implanted gold thread, the catheter positions were visible in the post-operative images. The TVI(max) was visualized for each catheter. The biochemical changes could thereby be related to their anatomical origin, facilitating interpretation of results.

  • 71.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Didzar, Nil
    Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A finite element model for biochemical monitoring in the brain during deep brain stimulation (poster)2010Conference paper (Refereed)
  • 72.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Dizdar, Nil
    Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Kullman, Anita
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A Finite Model for Biochemical Monitoring in the Brain during Deep Brain Stimulation (oral)2010Conference paper (Refereed)
  • 73.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Software for Patient Specific Modeling and Simulation of Deep Brain Stimulation (poster)2011Conference paper (Refereed)
  • 74.
    Draijer, Matthijs J
    et al.
    University of Twente.
    Hondebrink, Erwin
    University of Twente.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    G van Leeuwen, Ton
    University of Twente.
    Steenbergen, Wiendelt
    University of Twente.
    Relation between the contrast in time integrated dynamic speckle patterns and the power spectral density of their temporal intensity fluctuations2010In: OPTICS EXPRESS, ISSN 1094-4087, Vol. 18, no 21, p. 21883-21891Article in journal (Refereed)
    Abstract [en]

    Scattering fluid flux can be quantified with coherent light, either from the contrast of speckle patterns, or from the moments of the power spectrum of intensity fluctuations. We present a theory connecting these approaches for the general case of mixed static-dynamic patterns of boiling speckles without prior assumptions regarding the particle dynamics. An expression is derived and tested relating the speckle contrast to the intensity power spectrum. Our theory demonstrates that in speckle contrast the concentration of moving particles dominates over the contribution of speed to the particle flux. Our theory provides a basis for comparison of both approaches when used for studying tissue perfusion.

  • 75.
    Droog Tesselaar, Erik
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Henricson, Joakim
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Nilsson, Gert E.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Burn Unit . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    A protocol for iontophoresis of acetylcholine and sodium nitroprusside that minimises nonspecific vasodilatory effects2004In: Microvascular research, ISSN 0026-2862, Vol. 67, no 2, p. 197-202Article in journal (Refereed)
    Abstract [en]

    Iontophoresis of vasoactive substances is a promising tool for studying pharmacological aspects of the (patho)physiology of the microvasculature. However, nonspecific microvascular responses are a common problem in most protocols used. We studied the effect of current density (mA/cm2), charge density (mC/cm2), drug concentration (mass %) and vehicle concentration (M) on the nonspecific vasodilatation during iontophoresis of sodium chloride, acetylcholine (ACh) and sodium nitroprusside (SNP).

    We found that nonspecific vasodilatation depended on current density and charge density in both anodal and cathodal iontophoresis. The responses to ACh and SNP were dependent on current density, charge density and drug concentration. We found that by limiting current density (<0.01 mA/cm2) and charge density (<7.8 mC/cm2) and with adjusted concentrations for drugs and vehicles, it is possible to prevent nonspecific effects during iontophoresis of ACh and SNP, while maximum drug effects (plateaus in the dose–response curves) are still obtained. These new findings are important for future iontophoresis studies in which vasoactive drugs are used to assess microvascular function because the presented approach has advantages compared to older techniques, which mainly have attempted to suppress or compensate for the nonspecific responses during iontophoresis by the use of local anaesthetics or the measurement of drug-minus-vehicle responses, both of which present well-known experimental shortcomings.

  • 76.
    Durke, Anna
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Lindfors, Lina
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    En jämförelse mellan svenska mammografer med film-skärm system och nivåer satta av europeiska kommissionen2005Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att ta reda på hur svenska mammografiavdelningar står sig mot det europeiska protokollet undersöks nio mammografiavdelningar. Till hjälp har ett CDMAM-fantom version 3.4 och fyra plexiglasskivor använts för att simulera ett normaltjockt bröst. Även ljusskåpen och filmens egenskaper har undersökts och jämförts med kraven i europeiska protokollet. Avgränsningar har gjorts då koncentreringen ligger på mammografer som använder sig av film-skärm system.

    Röntgenbilderna har studerats utan tekniska hjälpmedel. Efter bedömning och poängsättning av bilderna på CDMAM-fantomet har värdena förts in i ett Excel-program där värdena presenteras i grafer. Från graferna utvärderas om bildkvaliteten ligger inom

    gränserna som anges för bra bildkvalitet. Det är endast ett av sjukhusen som ligger inom gränsen för bra bildkvalitet.

    Jämförelser har gjorts för att undersöka hur filmens egenskaper påverkar bildkvaliteten och om stråldosen har betydelse för bildkvaliteten. Samma sjukhus som har den högsta stråldosen har också den bästa bildkvaliteten.

  • 77.
    Eriksson, Charlotte
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Optimization of Dual Energy data acquisition using CdTe-detectors with electronic spectrum splitting2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Dual energy imaging has made it possible to enhance contrast in medical images using images containing different energy information, by combining low and high energy images. Dual energy data can either be acquired using double exposures or splitting the energy spectrum into two images using one exposure.

    This thesis presents investigations of dual energy imaging using a detector solution developed by XCounter which provides dual energy images in a single exposure with a threshold separating low and high energy images. Phantom experiments with phantoms of aluminum and plexiglas were performed using weighted logarithmic subtraction and basis material decomposition to produce dual energy images. Methods were validated and images were evaluated in terms of signal difference in noise ratio to find the threshold and tube voltage combination for optimum energy spectrum separation. The methods were also tested on biological materials using bone, soft tissue and iodine solution as contrast enhancer, to investigate K-edge imaging. 

    Optimal separation of plexiglas and aluminum were found at 70 kVp and the threshold parameter set within a range of 8 to 9, which corresponds to approximately 30 to 34 keV. For K-edge imaging, the optimum separation were found close to K-edge energy of iodine. The results found in the phantom study correlated with results from the biological material study.

  • 78. Eriksson, O.
    et al.
    Johansson, Johannes
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Finite element simulations of rf lesions in porcine brain2002Conference paper (Refereed)
  • 79.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Characterisation of brain electrodes for ablative neurosurgery1999Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stereotactic ablative neurosurgery with radio frequency current is regularly performed on patients with movement disorders, for instance Parkinson's disease. Even though the technique has been used for ablation in the brain for almost 50 years, nobody has suggested a standardised way of testing the electrodes used for ablative surgery.

    Within the framework of this thesis a computer-assisted video system has been developed for a proposed standardised method for in vitro estimation of protein clots generated by radio frequency lesioning electrodes. The system can be used for documentation of lesion growth by video recording, as well as lesion shape and size Oength, width and volume) calculations by use of two perpendicularly captured images of the protein clot. The system has been used for this purpose in a comparative study including two different test solutions (albumin and hen's egg white), three different temperature settings (70, 80 or 90°C) and five different brain electrode configurations, three monopolar (2mm diameter and 4mm tip, 1mm diameter and 2 or 4mm tip) and two bipolar (1 or 2mm diameter). Electrode configurations and parameter settings of the radio frequency generator greatly affect the size and shape of the coagulated lesion. Larger electrodes and higher temperature settings produce larger lesions, while the shape of the lesion is more dependent on the choice between monopolar or bipolar electrodes and the length of the active uninsulated electrode tip. The experiments performed in the albumin solution showed more regular, reproducible and homogeneous shapes and sizes compared to the experiments performed in hen's egg white. Protein clots generated by the electrodes in the albumin solution ranged in width from 2.2±0.1 to 5.3±0.lmm, length from 3.0±0.1 to 8.7±0.3mm and volume from 8.5±1.4 to 133.5±26.8mm3 , (m±s.d.,n=10). By using different test patterns, the video system has been  proven to be accurate and precise (random error 2%), giving repeatable and reproducible results.

    A method for simulation of the thermal characteristics of brain lesioning electrodes using the finite element method has also been developed. Finite element simulations of thein vitro experiment give valuable information of the lesion growth and final size when using different thermal properties and conditions. No deviation in width and distance from tip was seen when comparing finite element simulations of a power distribution at the distal part of the tip to in vitro experiments. However, the length is somewhat underestimated.

    In conclusion, the developed computer-assisted video system can be used as a standard system for evaluation of radio frequency electrodes used in stereotactic ablative neurosurgery. The proposed albumin solution is superior to egg white and should be used as a test substrate. An FEM simulation offers a good approximation for assessment of the size of the in vitro lesion.

  • 80.
    Eriksson, Ola
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Backlund, Erik Olof
    Lindstam, Håkan
    Lundberg, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Lindström, Sivert
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Stereotactic RF-lesioning - A study in the pig brain2000In: Scandinavian Neurosurgical Society Meeting,2000, 2000Conference paper (Refereed)
  • 81.
    Eriksson, Ola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Backlund, Erik-Olof
    Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Lundberg, Peter
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Lindstam, Håkan
    Linköping University, Department of Medicine and Care, Radiology. Linköping University, Faculty of Health Sciences.
    Lindström, Sivert
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Experimental radiofrequency brain lesions: a volumetric study2002In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 51, no 3, p. 781-788Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE : This study describes the production, under strictly standardized and controlled conditions, of radiofrequency lesions with identical neurogenerator settings: in vitro in two different albumin solutions (nongelatinous and gelatinous) and in vivo in the thalamus of the pig.

    METHODS : The radiofrequency lesions were investigated in vitro by the use of a specially designed video system and in vivo by magnetic resonance imaging. Moreover, the size of the in vivo lesions was estimated with the use of histological sectioning. The statistical analysis included the calculation of a correlation coefficient for the length, width, and volume for each lesion estimation.

    RESULTS : A high correlation (R = 0.96, P < 0.005; n = 14) was found between clot sizes in the two albumin solutions. Albumin clots generated in gelatinous albumin showed systematically larger volumes. In the pig, two concentric zones were seen in all magnetic resonance images and all histological preparations. The width correlation of the completely coagulated brain tissue (inner zones) was R = 0.94, P < 0.005, and n = 7. The corresponding correlation between magnetic resonance images and gelatinous albumin was R = 0.93, P < 0.005, and n = 7. As a rule, the in vitro clots were smaller than the outer zone but larger than the inner zone of the magnetic resonance imaging-recorded lesions for all of the electrode and temperature combinations tested. In vivo lesions generated with the same electrode and parameter settings showed high reproducibility.

    CONCLUSION : The value of presurgical electrode tests to validate the electrode function and lesion size in vitro has become evident in this study, which shows a high correlation between the in vitro albumin clots and the in vivo lesions observed on magnetic resonance images.

  • 82.
    Eriksson, Ola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Optical changes as a marker for lesion size estimation during radio frequency ablation: a model study2001In: SPIE Proceedings | Volume 4254 | Guidance, Surgical-Assist and Treatment Systems / [ed] Warren S. Grundfest; David A. Benaron; Tuan Vo-Dinh, 2001, Vol. 4254, p. 164-171Conference paper (Other academic)
    Abstract [en]

    Stereotactic radiofrequency (RF)-lesioning in the central part of the brain is performed on patients that, for instance, have severe movement or psychiatric disorders. The size of the generated lesion can to some extent be controlled by RF-generator settings such as temperature and time as well as the electrode configuration. Today, MR- imaging and CT are the essential diagnostic methods to confirm the lesion size in vivo. The aim of this study was to investigate whether it is possible to use changes in the reflected light intensity and laser Doppler flowmetry as a marker for size estimation during RF-lesioning.

  • 83.
    Eriksson, Ola
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Kullberg, G
    Rehncrona, S
    Invitro evaluation of brain lesioning electrodes (Leksell) using a computer-based video system1997In: XIIth Meeting World Society Stereotactic Functional Neurosurgery,1997, 1997Conference paper (Refereed)
  • 84.
    Eriksson, Ola
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wren, Joakim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    Loyd, Dan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics.
    A finite element model for brain electrodes and its comparison with in-vitro albumin lesions1999In: Congress of the International Society for Neurosurgical Technology and Instrument Invention ISNTII,1999, 1999Conference paper (Other academic)
  • 85.
    Eriksson, Olle
    et al.
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, Faculty of Arts and Sciences.
    Backlund, EO
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Lindstam, H
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    A method for comparisons between in vitro, in vivo and post mortem appearance of tereotactic RF-lesions in the pig brain.2000Conference paper (Other academic)
  • 86.
    Ewerlöf, Maria
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Salerud, E. Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Estimating skin blood saturation by selecting a subset of hyperspectral imaging data2015In: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues XIII / [ed] Daniel L. Farkas; Dan V. Nicolau; Robert C. Leif, SPIE, 2015, Vol. 9328Conference paper (Refereed)
    Abstract [en]

    Skin blood haemoglobin saturation (𝑠b) can be estimated with hyperspectral imaging using the wavelength (λ) range of 450-700 nm where haemoglobin absorption displays distinct spectral characteristics. Depending on the image size and photon transport algorithm, computations may be demanding. Therefore, this work aims to evaluate subsets with a reduced number of wavelengths for 𝑠b estimation. White Monte Carlo simulations are performed using a two-layered tissue model with discrete values for epidermal thickness (𝑇epi) and the reduced scattering coefficient (μ's ), mimicking an imaging setup. A detected intensity look-up table is calculated for a range of model parameter values relevant to human skin, adding absorption effects in the post-processing. Skin model parameters, including absorbers, are; μ's (λ), 𝑇epi, haemoglobin saturation (𝑠b), tissue fraction blood (𝑐b) and tissue fraction melanin (𝑐mel). The skin model paired with the look-up table allow spectra to be calculated swiftly. Three inverse models with varying number of free parameters are evaluated: A(𝑠b, 𝑐b), B(𝑠b, 𝑐b, 𝑐mel) and C(all parameters free). Fourteen wavelength candidates are selected by analysing the maximal spectral sensitivity to 𝑠b and minimizing the sensitivity to 𝑐b. All possible combinations of these candidates with three, four and 14 wavelengths, as well as the full spectral range, are evaluated for estimating 𝑠b for 1000 randomly generated evaluation spectra. The results show that the simplified models A and B estimated 𝑠b accurately using four wavelengths (mean error 2.2% for model B). If the number of wavelengths increased, the model complexity needed to be increased to avoid poor estimations.

  • 87.
    Falk, Magnus
    et al.
    Linköping University, Department of Medical and Health Sciences, General Practice. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Primary Health Care Centres. Östergötlands Läns Landsting, Local Health Care Services in the West of Östergötland, Unit of Research and Development in Local Health Care, County of Östergötland.
    Ilias, Michail
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson, Chris
    Linköping University, Department of Clinical and Experimental Medicine, Dermatology and Venerology. Linköping University, Faculty of Health Sciences.
    Inter-observer variability in reading of phototest reactions with sharply or diffusely delineated borders2008In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 14, no 4, p. 397-402Article in journal (Refereed)
    Abstract [en]

    Background: In both clinical and experimental phototesting, naked eye assessment of erythema has been the main assessment parameter. As with all subjective assessment, variability in recorded results due to variable circumstances around the performance and reading of tests influences reliability and utility of data whether they be interpreted for an individual patient or for a group of research subjects.

    Methods: In the present study, variability in the reporting of diameter of ultraviolet B (UVB) erythema has been studied. The erythematous reactions were assessed by the naked eye and with the help of a millimetre-graded ruler by a group of dermatologists and dermatological trainees. Reaction size, objectively quantified by means of laser Doppler perfusion imaging (LDPI) using thresholding of the reaction perfusion, and known size of UVB provocation were used as yardsticks in order to quantify this variability.

    Results: Agreement between observers, against known size, was excellent for reactions with a sharp border, but for reactions with a diffuse or indistinct border there was a substantial inter-observer variability. This was also true for the comparison between naked-eye reading and LDPI assessment of the reaction size.

    Conclusion: It is concluded that if naked-eye readings are to be the outcome measurement, then provocations/protocols producing distinct borders are an advantage. If borders between provoked and unprovoked skin can be expected to be diffuse, i.e. part of a continuum of response, the use of objective, bioengineering techniques such as LDPI is required. Quantitative methods are also the basis for more detailed presentation and interpretation of test results including information on dose response above the minimal erythema dose.

  • 88.
    Fors, Carina
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Evaluation of a Laser Doppler System for Myocardial Perfusion Monitoring2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Coronary artery bypass graft (CABG) surgery is a common treatment for patients with coronary artery disease. A potential complication of CABG is myocardial ischemia or infarction. In this thesis, a method - based on laser Doppler flowmetry (LDF) - for detection of intra- and postoperative ischemia by myocardial perfusion monitoring is evaluated.

    LDF is sensitive to motion artifacts. In previous studies, a method for reduction of motion artifacts when measuring on the beating heart has been developed. By using the ECG as a reference, the perfusion signal is measured in intervals during the cardiac cycle where the cardiac motion is at a minimum, thus minimizing the artifacts in the perfusion signal.

    The aim of this thesis was to investigate the possibilities to use the ECG-triggered laser Doppler system for continuous monitoring of myocardial perfusion in humans during and after CABG surgery. Two studies were performed. In the first study, changes in myocardial perfusion during CABG surgery were investigated (n = 13), while the second study focused on postoperative measurements (n = 13). In addition, an ECG-triggering method was implemented and evaluated.

    It was found that the large variations in myocardial perfusion during CABG surgery could be monitored with the ECG-triggered laser Doppler system. Furthermore, a perfusion signal of good quality could be registered postoperatively from the closed chest in ten out of thirteen patients. In eight out of ten patients, a proper signal was obtained also the following morning, i.e., about 20 hours after probe insertion. The results show that respiration and blood pressure can have an influence on the perfusion signal.

    In conclusion, the results indicate that the method is able to detect fluctuations in myocardial perfusion under favourable circumstances. However, high heart rate, abnormal cardiac motion, improper probe attachment and limitations in the ECG-triggering method may result in variations in the perfusion signal that are not related to tissue perfusion.

    List of papers
    1. Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique
    Open this publication in new window or tab >>Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique
    2005 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, no 5, p. 582-588Article in journal (Refereed) Published
    Abstract [en]

    Electrocardiogram (ECG)—triggered laser Doppler perfusion monitoring (LDPM) was used to assess myocardial perfusion, with minimum myocardial tissue motion influence, during coronary artery bypass grafting (CABG). Thirteen subjects were investigated at six phases: pre- and post-CABG; post aorta cross-clamping; pre and post left internal mammary artery (LIMA) graft declamping; and post aorta declamping. The perfusion signal was calculated in late systole and late diastole, with expected minimum tissue motion, and compared with arrested heart measurements. Patient conditions or artifacts caused by surgical activity made it impossible to perform and analyse data in all six phases for some patients. No significant (n=5) difference between perfusion signals pre- and post-CABG was found. Diastolic perfusion signal levels were significantly (p<0.02) lower compared with systolic levels. After aorta cross-clamping, the signal level was almost zero. A distinct perfusion signal increase after LIMA and aorta declamping, compared with pre-LIMA declamping, was found in ten cases out of 13. A significantly (p<0.04) lower perfusion signal in the arrested heart compared with in the beating heart was registered. Influence from mechanical ventilation was observed in 14 measurements out of 17. In conclusion, ECG-triggered LDPM can be used to assess myocardial perfusion during CABG. Perfusion signals were lower in the arrested heart compared with in the beating heart and in late diastole compared with late systole. No significant difference between pre- and post-CABG was found.

    Place, publisher, year, edition, pages
    Springer, 2005
    Keywords
    Laser Doppler perfusion monitoring, Coronary artery bypass grafting, Beating heart, Myocardial microcirculation, Movement artifacts, Electrocardiography
    National Category
    Medical Laboratory and Measurements Technologies
    Identifiers
    urn:nbn:se:liu:diva-14612 (URN)10.1007/BF02351031 (DOI)000234262300007 ()2-s2.0-29244438810 (Scopus ID)
    Available from: 2007-08-27 Created: 2007-08-27 Last updated: 2017-12-13Bibliographically approved
    2. Analysis of breathing-related variations in ECG-triggered laser Doppler perfusion signals measured on the beating heart during surgery
    Open this publication in new window or tab >>Analysis of breathing-related variations in ECG-triggered laser Doppler perfusion signals measured on the beating heart during surgery
    2006 (English)In: Computers in cardiology, ISSN 0276-6574, Vol. 33, p. 181-184Article in journal (Refereed) Published
    Abstract [en]

    Laser Doppler perfusion monitoring (LDPM) is a

    method to assess microvascular perfusion. A modified,

    ECG-triggered LDPM system has been developed to

    measure myocardial perfusion with minimum influence

    from heart motion. With this method, one systolic (PLS)

    and one diastolic (PLD) perfusion value is obtained.

    The aim of this study was to analyse breathing-related

    variations in PLS and PLD measured during open-heart

    surgery. The phase delays between PLS, PLD, mean

    arterial blood pressure (MAP), heart rate and, indirectly,

    the respiration were determined.

    MAP tended to be in phase with or precede the

    variations in PLD, i.e., PLD was at a maximum at the end

    of inspiration or at the beginning of expiration. No clear

    relation between PLS and any of the other signals could

    be found.

    National Category
    Medical Laboratory and Measurements Technologies
    Identifiers
    urn:nbn:se:liu:diva-14613 (URN)2-s2.0-50149103402 (Scopus ID)
    Available from: 2007-08-27 Created: 2007-08-27 Last updated: 2017-12-13Bibliographically approved
    3. Determination of appropriate times during the cardiac cycle for online laser Doppler measurements of myocardial perfusion
    Open this publication in new window or tab >>Determination of appropriate times during the cardiac cycle for online laser Doppler measurements of myocardial perfusion
    2007 (English)Article in journal (Refereed) Submitted
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14614 (URN)
    Available from: 2007-08-27 Created: 2007-08-27 Last updated: 2017-02-16Bibliographically approved
  • 89.
    Fors, Carina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Analysis of Breathing-related Variations in ECG-triggered Laser Doppler Perfusion Signals Measured on the Beating Heart during Surgery2006In: IEEE 2006,2006, 2006, p. 181-184Conference paper (Refereed)
    Abstract [en]

        

  • 90.
    Fors, Carina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Online Laser Doppler Measurements of Myocardial Perfusion2008In: IFMBE Proceedings 22,2008, Springer Berlin Heidelberg , 2008, p. 1718-1721Conference paper (Refereed)
    Abstract [en]

    Laser Doppler perfusion monitoring is a suitable method for microvascular blood perfusion measurements. When used on a moving tissue or organ, the Doppler signal arising from the moving blood cells may be distorted. ECG triggering of the laser Doppler signal can be used for reducing the influence from movements during measurements on the beating heart. The aim of this study was to determine the most appropriate triggering intervals during the cardiac cycle for online measurements. Recordings from thirteen coronary artery bypass graft (CABG) patients were included in the study. During surgery, the fibre-optic probe was passed through the chest wall and sutured to the left anterior ventricular wall with the probe tip inserted 3–5 mm into the myocardium. After the patient arrived at the intensive care unit a second measurement was initiated and lasted for about two hours. Before the probe was removed a third measurement was performed for about 5 minutes the following morning. A total of 97 data sequences were analysed and the intervals of low and stable perfusion signal were compared to the positions of the T and P peaks in the ECG.

    It was found that the most appropriate time intervals were in late systole at the T peak [−3, 9] ms and just before the P peak [−28, -10] ms in late diastole. However, the position of these intervals may vary between individuals, because of e.g., abnormal cardiac motion. With the use of the appropriate interval online measurement of the myocardial perfusion on a beating heart appears possible.

  • 91.
    Fors, Carina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Postoperativa mätningar av myokardperfusion med EKG-triggad laser Doppler2006In: Medicinteknikdagarna 2006,2006, 2006Conference paper (Other academic)
  • 92.
    Fors, Carina
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Casimir Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Analysis of breathing-related variations in ECG-triggered laser Doppler perfusion signals measured on the beating heart during surgery2006In: Computers in cardiology, ISSN 0276-6574, Vol. 33, p. 181-184Article in journal (Refereed)
    Abstract [en]

    Laser Doppler perfusion monitoring (LDPM) is a

    method to assess microvascular perfusion. A modified,

    ECG-triggered LDPM system has been developed to

    measure myocardial perfusion with minimum influence

    from heart motion. With this method, one systolic (PLS)

    and one diastolic (PLD) perfusion value is obtained.

    The aim of this study was to analyse breathing-related

    variations in PLS and PLD measured during open-heart

    surgery. The phase delays between PLS, PLD, mean

    arterial blood pressure (MAP), heart rate and, indirectly,

    the respiration were determined.

    MAP tended to be in phase with or precede the

    variations in PLD, i.e., PLD was at a maximum at the end

    of inspiration or at the beginning of expiration. No clear

    relation between PLS and any of the other signals could

    be found.

  • 93.
    Fors, Carina
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Casimir Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Determination of appropriate times during the cardiac cycle for online laser Doppler measurements of myocardial perfusion2007Article in journal (Refereed)
  • 94.
    Fors, Carina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Karlsson, Daniel M G
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Myocardial perfusion assessment using an ECG triggered laser doppler technique2005In: 13th Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005, Umeå: IFMBE , 2005, p. 83-84Conference paper (Refereed)
  • 95.
    Fors, Carina
    et al.
    Linköping University, Department of Biomedical Engineering.
    Karlsson, M G Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    A system for on-line laser Doppler monitoring of ECG-traced myocardial perfusion2004In: IEEE EMBS,2004, Piscataway, NJ, USA: IEEE , 2004, p. 3796-Conference paper (Refereed)
  • 96.
    Franzén, Lennart
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Pathology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pathology and Clinical Genetics.
    Ghassemifar, M.R.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Tarpila, Erkki
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Actin fiber orientation in connective tissue contraction. A quantitative study using the perforated rat mesentery model.1996In: Wound Repair and Regeneration, ISSN 1067-1927, E-ISSN 1524-475X, Vol. 4, p. 454-460Article in journal (Refereed)
  • 97.
    Fredly, Siv
    et al.
    Department of Neonatal Intensive Care, Oslo University Hospital, Ullevål, Oslo, Norway / Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
    Fugelseth, Drude
    Department of Neonatal Intensive Care, Oslo University Hospital, Ullevål, Oslo, Norway / Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
    Nygaard, Cathrine S
    Department of Neonatal Intensive Care, Oslo University Hospital, Ullevål, Oslo, Norway.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Stiris, Tom
    Department of Neonatal Intensive Care, Oslo University Hospital, Ullevål, Oslo, Norway / Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
    Kvernebo, Knut
    Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway / Department of Cardiothoracic Surgery, Oslo University Hospital, Ullevål, Oslo, Norway.
    Noninvasive assessments of oxygen delivery from the microcirculation to skin in hypothermia-treated asphyxiated newborn infants2016In: Pediatric Research, ISSN 0031-3998, E-ISSN 1530-0447, Vol. 76, no 6, p. 902-906Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    Therapeutic hypothermia (TH) has become standard treatment for severe and moderate hypoxic-ischemic neonatal encephalopathy (HIE). Our group has developed an optically based, noninvasive concept of assessing the capacity for oxygen delivery from the microcirculation to the cells of a tissue under investigation. The hypothesis was that mechanisms of reduced oxygen delivery due to reduced metabolism in cooled asphyxiated neonates could be characterized with this concept.

    METHODS:

    The skin of 28 asphyxiated newborn infants was studied on days 1 and 3 during TH and on day 4 following rewarming with laser Doppler perfusion measurements (LDPM), computer-assisted video microscopy (CAVM), and diffuse reflectance spectroscopy (DRS). Twenty-five healthy neonates served as a control group.

    RESULTS:

    The LDPM decreased during cooling (P < 0.01). Functional capillary density was higher both during and following TH compared with control infants (P < 0.01). Capillary flow velocities were reduced during TH (P < 0.05). The heterogeneity of the flow velocities was larger in the HIE infants than in the control infants. Tissue oxygen extraction was higher during TH (P < 0.01).

    CONCLUSION:

    This study indicates that assessments of skin microvascular density, capillary flow velocity, and oxygen extraction can be used to characterize reduced oxygen delivery to cells during TH

  • 98.
    Fredly, Siv
    et al.
    Oslo University Hospital, Norway; University of Oslo, Norway.
    Fugelseth, Drude
    Oslo University Hospital, Norway; University of Oslo, Norway.
    Wester, Torjus
    University of Oslo, Norway; Oslo University Hospital, Norway.
    Häggblad, Erik
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Oslo University Hospital, Norway.
    Kvernebo, Knut
    University of Oslo, Norway; Oslo University Hospital, Norway.
    Skin microcirculation in healthy term newborn infants - assessment of morphology, perfusion and oxygenation2015In: Clinical hemorheology and microcirculation, ISSN 1386-0291, E-ISSN 1875-8622, Vol. 59, no 4, p. 309-322Article in journal (Refereed)
    Abstract [en]

    Despite microcirculations fundamental role, assessments of its function are limited. We explored the applicability of Computer Assisted Video Microscope (CAVM), Laser Doppler Perfusion Measurements (LDPM) and Diffuse Reflectance Spectroscopy (DRS) to study skin microvascular morphology, perfusion and oxygen saturation in twenty-five healthy newborns day 1-3 of life. Results: Day 1-3 (mean (SD)): Microvascular density (CAVM; number of microvessels crossing a grid of lines/mm line, c/mm): Chest: 11.3 (1.5), 11.0 (1.7), 10.7 (1.6). Hand: 13.2 (2.0), 13.2 (1.9), 12.4 (1.6). Capillary density was significantly higher in the hand than in the chest each day (p less than 0.001). Perfusion (LDPM; arbitrary units): Chest: 109.1 (26.0), 101.4 (24.6), 100.8 (25.3). Hand: 58.9 (17.5), 54.3 (15.8), 46.9 (14.8). Perfusion was significantly higher in the chest than in the hand each day (p less than 0.01). Microvascular oxygen saturation (DRS; %): Chest: 88.1 (5.2), 87.8 (10.0), 86.7 (9.0). Hand: 79.9 (15.2), 82.7 (11.8), 82.2 (12.1) (p less than 0.05). Capillary flow velocities (CAVM) were similar in the chest and hand: 60-70% capillaries had "continuous high flow" and 30-40% "continuous low flow". Multimodal skin microvascular assessments with CAVM, LDPM and DRS are feasible with reproducible data in newborns. The hand has lower perfusion, higher capillary density and higher oxygen extraction than the chest.

  • 99.
    Fredly, Siv
    et al.
    Department of Neonatal Intensive Care Unit, Oslo University hospital, Ullevål, Oslo Norway.
    Häggblad, Erik
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Kvernebo, Knut
    Faculty of Medicine, University of Oslo, Oslo, Norway.
    Fugelseth, Drude
    Department of Neonatal Intensive Care Unit, Oslo University hospital, Ullevål, Oslo Norway.
    Skin microcirculation in healthy newborns- assessments of morphology, perfusion and oxygenation2010Conference paper (Refereed)
  • 100.
    Fredly, Siv
    et al.
    Oslo University Hospital, Ullevål, Norway.
    Kvernebo, Knut
    Oslo University Hospital, Ullevål, Norway.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Biophotonic Assessment of Microcirculation in Healthy Newborn Children2013Conference paper (Other academic)
1234567 51 - 100 of 565
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