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  • 2151.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Ehnfors, M
    Linkoping Univ, S-58183 Linkoping, Sweden Univ Orebro, Dept Caring Sci, S-70130 Orebro, Sweden Swedish Nurses Assoc, Stockholm, Sweden.
    Ridderstolpe, L
    Linkoping Univ, S-58183 Linkoping, Sweden Univ Orebro, Dept Caring Sci, S-70130 Orebro, Sweden Swedish Nurses Assoc, Stockholm, Sweden.
    Towards a multi-professional patient record - A study of the headings used in clinical practice1999Inngår i: JAMIA Journal of the American Medical Informatics Association, ISSN 1067-5027, E-ISSN 1527-974XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports on the differences and similarities of headings used in patient records by Swedish health care professionals, nurses, occupational therapists, physiotherapists, dietitians, speech therapists, medical social workers and general practitioners. The background to the study is a national project where representatives from the different health care professions have worked together for two years in an effort to develop a multi-professional database of terms for the health care sector. The study reports on an analysis of the existing multi-professional lists of headings with respect to structure, degree of specialization, synonyms and homonyms. The study is descriptive in nature, gives a status report on the variety of headings used in clinical practice, provides necessary material for a normative approach focusing on a truly multi-professional patient record in the future.

  • 2152.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Ehnfors, Margareta
    Örebro Universitet Sverige.
    Ridderstolpe, L
    Towards a multi-professional patient record - a study of the headings used in clinical practice1999Inngår i: AMIA99,1999, Philadelphia: Hanley & Belfus Inc , 1999Konferansepaper (Fagfellevurdert)
  • 2153.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Ehnfors, Margareta
    Dept of Caring Sciences Örebro University, Sweden.
    Ridderstolpe, L
    Towards a multi-professional patient record - a study of the use of headings1999Inngår i: Medical Informatics Europe99,1999, Amsterdam: IOS Press , 1999, s. 813-Konferansepaper (Fagfellevurdert)
  • 2154.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Johansson, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Linnarsson, Rolf
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Experiences from the use of data-driven decision support in different environments1994Inngår i: Computers in Biology and Medicine, ISSN 0010-4825, E-ISSN 1879-0534, Vol. 24, s. 397-404Artikkel i tidsskrift (Fagfellevurdert)
  • 2155.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Karlsson, Daniel
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Petersson, Håkan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Chen, Rong
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Nyström, Mikael
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Sundvall, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Advancement in the standardisation of the EHR2007Inngår i: 5th Scandinavian Conference on Health Informatics 2007, 2007Konferansepaper (Fagfellevurdert)
  • 2156.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Lanhammar, Erik
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Multi-search - a search tool for literature retrieval1996Inngår i: Medical Informatics Europe 96,1996, Amsterdam: IOS Press , 1996, s. 619-Konferansepaper (Fagfellevurdert)
  • 2157.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Nilsson, Göran
    Centrallasarettet Västerås.
    Bandh, S
    Centrallasarettet Västerås.
    Jonason, Tommy
    Centrallasarettet Västerås.
    Ahrén, Tom
    Centrallasarettet Västerås.
    Deduction of biphasic phase response curves from ventricular parasystole1989Inngår i: Pacing and Clinical Electrophysiology, ISSN 0147-8389, E-ISSN 1540-8159, Vol. 12, s. 793-804Artikkel i tidsskrift (Fagfellevurdert)
  • 2158.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Nilsson, Göran
    Centrallasarettet Västerås.
    Bandh, S
    Centrallasarettet Västerås.
    Jonason, Tommy
    Centrallasarettet Västerås.
    Ahrén, Tom
    Centrallasarettet Västerås.
    Ringqvist, I
    Regionsjukhuset Umeå.
    Deduction of triphasic phase response curves from ventricular parasystole1989Inngår i: Pacing and Clinical Electrophysiology, ISSN 0147-8389, E-ISSN 1540-8159, Vol. 12, s. 1104-1114Artikkel i tidsskrift (Fagfellevurdert)
  • 2159.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Shahsavar, Nosrat
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Xiao-Ming, Gao
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Arkad, Kristina
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Johansson, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Data driven medical decision support based on Arden Syntax within the HELIOS environment1994Inngår i: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 45, nr suppl, s. S97-S106Artikkel i tidsskrift (Fagfellevurdert)
  • 2160.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Tanaka, T
    University of Tokyo .
    Nygårds, Mats-Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Furukawa, T
    University of Tokyo .
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Computer simulation of cardiac pacing1988Inngår i: Pacing and Clinical Electrophysiology, ISSN 0147-8389, E-ISSN 1540-8159, Vol. 11, s. 83-95Artikkel i tidsskrift (Fagfellevurdert)
  • 2161.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Tanaka, T
    University of Tokyo Japan.
    Nygårds, Mats-Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    A mathematical model of cardiac conduction system including external pacemakers1985Inngår i: Computers in Cardiology 1985,1985, IEEE computer Society , 1985, s. 397-Konferansepaper (Fagfellevurdert)
  • 2162.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Wigertz, Ove
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Study programs in medical informatics at Linköping university1995Inngår i: Yearbook of Medical Informatics / [ed] Jan H. van Bemmel, Alexa T. McCray, Rotterdam: International Medical Informatics Association , 1995, s. 115-120Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 2163.
    Åhlfeldt, Hans
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Yongyu, Zhang
    Northwest Inst of Light Industry Xianyang, China.
    Nilsson, Göran
    Centrallasarettet Västerås.
    Ahrén, Tom
    Centrallasarettet Västerås.
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    The Hyperpace system - computer-aided analysis, simulation and education of cardiac arrhytmias1989Inngår i: Medical Inforamtics MEDINFO89,1989, Tokyo: Elsevier Science Publ , 1989, s. 483-Konferansepaper (Fagfellevurdert)
  • 2164.
    Åstrand, Olov
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet.
    Carlsson, Martin
    Länssjukhuset i Kalmar.
    Nilsson, Ingela
    Länssjukhuset i Kalmar.
    Lindström, Torbjörn
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet.
    Borga, Magnus
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Tekniska högskolan.
    Nyström, Fredrik
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet.
    Weight gain by hyperalimentation elevates C-reactive protein levels but does not affect circulating levels of adiponectin or resistin in healthy subjects2010Inngår i: European Journal of Endocrinology, ISSN 0804-4643, E-ISSN 1479-683X, Vol. 163, nr 6, s. 879-885Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: Increase of resistin and/or reduction of adiponectin have beenimplicated in the development of insulin resistance followingweight gain. We aimed to study this prospectively in humans.

    Design: Prospective and interventional with parallel control group.

    Methods: Twelve healthy men and six healthy women (age 26±6.6years) and an age-matched control group were recruited. Subjectsin the intervention group aimed for a bodyweight increase of5–15% by doubling the baseline caloric intake by eatingat least two fast food-based meals a day in combination withadoption of a sedentary lifestyle for 4 weeks.

    Results: Bodyweight increased from 67.6±9.1 to 74.0±11kg, P<0.001, by the intervention. Insulin levels increased(before: 27.4±12 pmol/l, after: 53.0±22 pmol/l,P=0.004), while plasma levels of adiponectin (before: 5038±3736ng/ml, after: 6739±7949 ng/ml, P=0.18) and resistin (before:21.8±19 ng/ml, after: 14.4±6.8 ng/ml, P=0.074)remained unchanged by the weight gain and were similar as incontrols. On the other hand, leptin levels increased about threefoldfollowing the intervention (before: 5.7±7.4, after: 16±20ng/ml, P=0.008), and also the inflammatory marker C-reactiveprotein (CRP) increased from 0.34±0.44 to 0.71±0.87mg/l, P=0.03, when two outliers >10 mg/l were disregarded.

    Conclusions: Hyperalimentation reduces insulin sensitivity when weight gainof 9% was combined with reduction of exercise. However, thelevels of resistin and adiponectin were unaffected by the intervention,while CRP levels increased within this short time period suggestingthat low-grade inflammation can occur early in the process ofdeveloping a metabolic syndrome.

     

  • 2165.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Functional brain atlas2014Konferansepaper (Annet vitenskapelig)
  • 2166.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Modelling, Simulaltion, and Visualization of Deep Brain Stimulation2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Deep brain stimulation (DBS) is an effective surgical treatment for neurological diseases such as essential tremor, Parkinsonʹs disease (PD) and dystonia. DBS has so far been used in more than 70 000 patients with movement disorders, and is currently in trial for intractable Gilles de la Tourette’s syndrome, obsessive compulsive disorders, depression, and epilepsy. DBS electrodes are implanted with stereotactic neurosurgical techniques in the deep regions of the brain. Chronic electrical stimulation is delivered to the electrodes from battery-operated pulse generators that are implanted below the clavicle.

    The clinical benefit of DBS is largely dependent on the spatial distribution of the electric field in relation to brain anatomy. To maximize therapeutic benefits while avoiding unwanted side-effects, knowledge of the distribution of the electric field in relation anatomy is essential. Due to difficulties in measuring electric fields in vivo, computerized analysis with finite element models have emerged as an alternative.

    The aim of the thesis was to investigate technical and clinical aspects of DBS by means of finite element models, simulations, and visualizations of the electric field and tissue anatomy. More specifically the effects of dilated perivascular spaces filled with cerebrospinal fluid on the electrical field generated by DBS was evaluated. A method for patient-specific finite element modelling and simulation of DBS was developed and used to investigate the anatomical distribution of the electric field in relation to clinical effects and side effects. Patient-specific models were later used to investigate the electric field in relation to effects on speech and movement during DBS in patients with PD (n=10). Patient-specific models and simulations were also used to evaluate the influence of heterogeneous isotropic and heterogeneous anisotropic tissue on the electric field during DBS. In addition, methods were developed for visualization of atlas-based and patient-specific anatomy in 3D for interpretation of anatomy, visualization of neural activation with the activating function, and visualization of tissue micro structure. 3D visualization of anatomy was used to assess electrode contact locations in relation to stimulation-induced side-effects (n=331) during DBS for patients with essential tremor (n=28). The modelling, simulation, and visualization of DBS provided detailed information about the distribution of the electric field and its connection to clinical effects and side-effects of stimulation. In conclusion, the results of this thesis provided insights that may help to improve DBS as a treatment for movement disorders as well as for other neurological diseases in the future.

    Delarbeid
    1. The effect of cystic cavities on deep brain stimulation in the basal ganglia: A simulation-based study
    Åpne denne publikasjonen i ny fane eller vindu >>The effect of cystic cavities on deep brain stimulation in the basal ganglia: A simulation-based study
    Vise andre…
    2006 (engelsk)Inngår i: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 3, nr 2, s. 132-138Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Although the therapeutic effect of deep brain stimulation (DBS) is well recognized, a fundamental understanding of the mechanisms responsible is still not known. In this study finite element method (FEM) modelling and simulation was used in order to study relative changes of the electrical field extension surrounding a monopolar DBS electrode positioned in grey matter. Due to the frequently appearing cystic cavities in the DBS-target globus pallidus internus, a nucleus of grey matter with and without a cerebrospinal fluid filled cystic cavity was modelled. The position, size and shape of the cyst were altered in relation to the electrode. The simulations demonstrated an electrical field around the active element with decreasing values in the radial direction. A stepwise change was present at the edge between grey and white matters. The cyst increased the radial extension and changed the shape of the electrical field substantially. The position, size and shape of the cyst were the main influencing factors. We suggest that cystic cavities in the DBS-target may result in closely related unexpected structures or neural fibre bundles being stimulated and could be one of the reasons for suboptimal clinical effects or stimulation-induced side effects. © 2006 IOP Publishing Ltd.

    sted, utgiver, år, opplag, sider
    Institute of Physics Publishing (IOPP), 2006
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-34125 (URN)10.1088/1741-2560/3/2/007 (DOI)000239673500007 ()16705269 (PubMedID)2-s2.0-33744911364 (Scopus ID)20869 (Lokal ID)20869 (Arkivnummer)20869 (OAI)
    Tilgjengelig fra: 2009-10-10 Laget: 2009-10-10 Sist oppdatert: 2017-12-13bibliografisk kontrollert
    2. Method for patient-specific finite element modeling and simulation of deep brain stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Method for patient-specific finite element modeling and simulation of deep brain stimulation
    Vise andre…
    2009 (engelsk)Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 47, nr 1, s. 21-28Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Deep brain stimulation (DBS) is an established treatment for Parkinsons disease. Success of DBS is highly dependent on electrode location and electrical parameter settings. The aim of this study was to develop a general method for setting up patient-specific 3D computer models of DBS, based on magnetic resonance images, and to demonstrate the use of such models for assessing the position of the electrode contacts and the distribution of the electric field in relation to individual patient anatomy. A software tool was developed for creating finite element DBS-models. The electric field generated by DBS was simulated in one patient and the result was visualized with isolevels and glyphs. The result was evaluated and it corresponded well with reported effects and side effects of stimulation. It was demonstrated that patient-specific finite element models and simulations of DBS can be useful for increasing the understanding of the clinical outcome of DBS.

    sted, utgiver, år, opplag, sider
    Springer, 2009
    Emneord
    Deep brain stimulation, Patient-specific, Simulation, Finite element, Glyph
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-16616 (URN)10.1007/s11517-008-0411-2 (DOI)000262483600004 ()18936999 (PubMedID)2-s2.0-58649107661 (Scopus ID)
    Merknad

    The original publication is available at www.springerlink.com: Mattias Åström, Ludvic U Zrinzo, Stephen Tisch, Elina Tripoliti, Marwan I Hariz and Karin Wårdell , Method for patient-specific finite element modeling and simulation of deep brain stimulation, 2009, Medical and Biological Engineering and Computing, (47), 1, 21-28. http://dx.doi.org/10.1007/s11517-008-0411-2 Copyright: Springer Science Business Media http://www.springerlink.com/

    Tilgjengelig fra: 2009-02-07 Laget: 2009-02-06 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    3. Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation
    Vise andre…
    2010 (engelsk)Inngår i: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 88, nr 4, s. 224-233Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Background/Aims: Deep brain stimulation (DBS) is widely used to treat motor symptoms in patients with advanced Parkinson’s disease. The aim of this study was to investigate the anatomical aspects of the electric field in relation to effects on speech and movement during DBS in the subthalamic nucleus. Methods: Patient-specific finite element models of DBS were developed for simulation of the electric field in 10 patients. In each patient, speech intelligibility and movement were assessed during 2 electrical settings, i.e. 4 V (high) and 2 V (low). The electric field was simulated for each electrical setting. Results: Movement was improved in all patients for both high and low electrical settings. In general, high-amplitude stimulation was more consistent in improving the motor scores than low-amplitude stimulation. In 6 cases, speech intelligibility was impaired during high-amplitude electrical settings. Stimulation of part of the fasciculus cerebellothalamicus from electrodes positioned medial and/or posterior to the center of the subthalamic nucleus was recognized as a possible cause of the stimulation-induced dysarthria. Conclusion: Special attention to stimulation-induced speech impairments should be taken in cases when active electrodes are positioned medial and/or posterior to the center of the subthalamic nucleus.

    Emneord
    Deep brain stimulation, Dysarthria, Speech intelligibility, Parkinson’s disease, Electric field, Fasciculus cerebellothalamicus
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-58057 (URN)10.1159/000314357 (DOI)000280136100004 ()
    Merknad

    Original Publication: Mattias Åström, Elina Tripoliti, Mawan I. Hariz, Ludvig U. Zrinzo, Irene Martinez-Torres, Patricia Limousin and Karin Wårdell, Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation, 2010, Stereotactic and Functional Neurosurgery, (88), 4, 224-233. http://dx.doi.org/10.1159/000314357 Copyright: S. Karger AG http://www.karger.com/

    Tilgjengelig fra: 2010-07-27 Laget: 2010-07-27 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    4. Influence of heterogeneous and anisotropic tissue conductivity on electric field distribution in deep brain stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Influence of heterogeneous and anisotropic tissue conductivity on electric field distribution in deep brain stimulation
    2012 (engelsk)Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 50, nr 1, s. 23-32Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The aim was to quantify the influence of heterogeneous isotropic and heterogeneous anisotropic tissue on the spatial distribution of the electric field during deep brain stimulation (DBS). Three finite element tissue models were created of one patient treated with DBS. Tissue conductivity was modelled as I) homogeneous isotropic, II) heterogeneous isotropic based on MRI, and III) heterogeneous anisotropic based on diffusion tensor MRI. Modelled DBS electrodes were positioned in the subthalamic area, the pallidum, and the internal capsule in each tissue model. Electric fields generated during DBS were simulated for each model and target-combination and visualized in 3D with isolevels at 0.20 (inner), and 0.05 V m-1 (outer). F-test and vector analysis was used for statistical evaluation of the distribution of the electric field. Heterogeneous isotropic tissue altered the spatial distribution of the electric field by up to 4% at inner, and up to 10% at outer isolevel. Heterogeneous anisotropic tissue had a larger impact on the distribution of the electric field with an influence of up to 18% and 15% at each isolevel, respectively. The influence of heterogeneous and anisotropic tissue on the electric field may be clinically relevant in anatomic regions that are functionally subdivided and surrounded by multiple fibres of passage.

    sted, utgiver, år, opplag, sider
    Springer, 2012
    Emneord
    Deep brain stimulation, Diffusion tensor, Finite element, Model, Simulation, Patient-specific
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-70087 (URN)10.1007/s11517-011-0842-z (DOI)000298648400003 ()
    Merknad

    funding agencies|Swedish Foundation for Strategic Research (SSF)||Swedish Research Council (VR)| 621-2008-3013 |Swedish Governmental Agency for Innovation Systems (VINNOVA)| 311-2006-7661 |

    Tilgjengelig fra: 2011-08-18 Laget: 2011-08-18 Sist oppdatert: 2017-12-08bibliografisk kontrollert
    5. Stimulation-induced side effects in the posterior subthalamic area: distribution, characteristics and visualization
    Åpne denne publikasjonen i ny fane eller vindu >>Stimulation-induced side effects in the posterior subthalamic area: distribution, characteristics and visualization
    2013 (engelsk)Inngår i: Clinical neurology and neurosurgery (Dutch-Flemish ed. Print), ISSN 0303-8467, E-ISSN 1872-6968, Vol. 15, nr 1, s. 65-71Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Objective: The posterior subthalamic area (PSA) is an emerging but relatively unexplored target for DBS treatment of tremor. The aim of the study was to explore the area further by evaluating the spatial distribution and the characteristics of stimulation-induced side effects in this area. Methods: Twenty-eight patients with essential tremor (ET) implanted with 33 DBS electrodes were evaluated concerning stimulation-induced side effects by testing each contact separately one year after surgery. The location of the side effects were plotted on axial slides of the Morel Stereotactic Atlas and a 3-dimensional model of the area for visualization was created. Results: Visualization of the contacts eliciting stimulation-induced side effects demonstrated that identical responses can be elicited from various points in the PSA and its vicinity. The majority of contacts inducing muscular affection and cerebellar symptoms, including dysarthria, could not be attributed to an effect on the internal capsule. Paresthesias, affecting various body parts were elicited throughout the area without a clear somatotopic pattern. Conclusion: Stimulation-induced side effects in the PSA and its vicinity are difficult to attribute to certain anatomical areas as the same response can be induced from various locations, and are thus of limited localizing value.

    sted, utgiver, år, opplag, sider
    Elsevier, 2013
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-70088 (URN)10.1016/j.clineuro.2012.04.015 (DOI)000312576300012 ()
    Tilgjengelig fra: 2011-08-18 Laget: 2011-08-18 Sist oppdatert: 2017-12-08bibliografisk kontrollert
  • 2167.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Neuronmodeling and DBS electric field simulations2014Konferansepaper (Annet vitenskapelig)
  • 2168.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan. Sapiens Steering Brain Stimulation BV, NL-5656 Eindhoven, Netherlands.
    Diczfalusy, Elin
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Martens, Hubert
    Sapiens Steering Brain Stimulation B.V., Eindhoven, The Netherlands.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Relationship between Neural Activation and Electric Field Distribution during Deep Brain Stimulation2015Inngår i: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 62, nr 2, s. 664-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Models and simulations are commonly used to study deep brain stimulation (DBS). Simulated stimulation fields are often defined and visualized by electric field isolevels or volumes of tissue activated (VTA). The aim of the present study was to evaluate the relationship between stimulation field strength as defined by the electric potential V, the electric field E, and the divergence of the electric field ∇(2) V, and neural activation. Axon cable models were developed and coupled to finite-element DBS models in three-dimensional (3-D). Field thresholds ( VT , ET, and ∇(2) VT ) were derived at the location of activation for various stimulation amplitudes (1 to 5 V), pulse widths (30 to 120 μs), and axon diameters (2.0 to 7.5 μm). Results showed that thresholds for VT and ∇(2) VT were highly dependent on the stimulation amplitude while ET were approximately independent of the amplitude for large axons. The activation field strength thresholds presented in this study may be used in future studies to approximate the VTA during model-based investigations of DBS without the need of computational axon models.

  • 2169.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Diczfalusy, Elin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Computational analysis of the electric field during deep brain stimulation (oral, invited)2010Konferansepaper (Fagfellevurdert)
  • 2170.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Diczfalusy, Elin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Software for patient-specific modeling and simulation of deep brain stimulation (poster)2011Konferansepaper (Annet vitenskapelig)
  • 2171.
    Åström, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Johansson, Johannes
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Hariz, Marwan
    Institute of Neurology London.
    Eriksson, Ola
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    The effect of cystic cavities on deep brain stimulation in the basal ganglia: A simulation-based study2006Inngår i: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 3, nr 2, s. 132-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although the therapeutic effect of deep brain stimulation (DBS) is well recognized, a fundamental understanding of the mechanisms responsible is still not known. In this study finite element method (FEM) modelling and simulation was used in order to study relative changes of the electrical field extension surrounding a monopolar DBS electrode positioned in grey matter. Due to the frequently appearing cystic cavities in the DBS-target globus pallidus internus, a nucleus of grey matter with and without a cerebrospinal fluid filled cystic cavity was modelled. The position, size and shape of the cyst were altered in relation to the electrode. The simulations demonstrated an electrical field around the active element with decreasing values in the radial direction. A stepwise change was present at the edge between grey and white matters. The cyst increased the radial extension and changed the shape of the electrical field substantially. The position, size and shape of the cyst were the main influencing factors. We suggest that cystic cavities in the DBS-target may result in closely related unexpected structures or neural fibre bundles being stimulated and could be one of the reasons for suboptimal clinical effects or stimulation-induced side effects. © 2006 IOP Publishing Ltd.

  • 2172.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Johansson, Johannes
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Modeling and simulation of electric fields generated by brain stimulation electrodes: the effect of cystic cavities in the basal ganglia2005Inngår i: Proceedings from the International IEEE EMBS Conference on Neural Engineering, IEEE , 2005, s. 198-201Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Deep brain stimulation (DBS) is an effective method for managing movement disorders. A small electrode is implanted in the basal ganglia and an electric potential is applied to one or more active elements of the electrode in order to simulate the neurons in the surrounding tissue. The fundamental understanding of the mechanisms responsible for the therapeutic DBS effects is unknown. A method to increase the knowledge is to use computer simulations. In this study the finite element method has been used for investigation of relative changes of the electrical field extension surrounding a monopolar DBS-electrode positioned in gray matter. Due to the frequently appearing cystic cavities in globus pallidus and putamen a nucleus of gray matter with and without a cerebrospinal fluid filled cystic cavity was modeled. The simulations demonstrated an electrical field around the active element with decreasing values in the radial direction. A stepwise change was present at the edge between gray and white matter. The cyst increased the radial extension and changed the shape of the field. This may result in closely related unexpected structures being stimulated and could be one of the reasons of reported postoperative complications.

  • 2173.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Lemair, Jean-Jaques
    Hôpital Gabriel Montpied, Service de Neurochirurgie, Clermont-Ferrand, France.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    The influence of brain tissue heterogeneity and anisotropy on deep brain stimulation in the subhalamic nucleus2009Konferansepaper (Fagfellevurdert)
  • 2174.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Lemaire, Jean-Jacques
    Clermont Université, Université d'Auvergne, EA 3295, Equipe de recherche en signal et imagerie médicale, Image- Guided Clinical Neuroscience and Connectomics (IGCNC), BP 10448, F-63000 Clermont-Ferrand, France/CHU Clermont-Ferrand, Service de Neurochirurgie, F-63003 Clermont-Ferrand, France.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Influence of heterogeneous and anisotropic tissue conductivity on electric field distribution in deep brain stimulation2012Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 50, nr 1, s. 23-32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim was to quantify the influence of heterogeneous isotropic and heterogeneous anisotropic tissue on the spatial distribution of the electric field during deep brain stimulation (DBS). Three finite element tissue models were created of one patient treated with DBS. Tissue conductivity was modelled as I) homogeneous isotropic, II) heterogeneous isotropic based on MRI, and III) heterogeneous anisotropic based on diffusion tensor MRI. Modelled DBS electrodes were positioned in the subthalamic area, the pallidum, and the internal capsule in each tissue model. Electric fields generated during DBS were simulated for each model and target-combination and visualized in 3D with isolevels at 0.20 (inner), and 0.05 V m-1 (outer). F-test and vector analysis was used for statistical evaluation of the distribution of the electric field. Heterogeneous isotropic tissue altered the spatial distribution of the electric field by up to 4% at inner, and up to 10% at outer isolevel. Heterogeneous anisotropic tissue had a larger impact on the distribution of the electric field with an influence of up to 18% and 15% at each isolevel, respectively. The influence of heterogeneous and anisotropic tissue on the electric field may be clinically relevant in anatomic regions that are functionally subdivided and surrounded by multiple fibres of passage.

  • 2175.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Medtronic, Sweden; Medtronic, Netherlands.
    Samuelsson, Jennifer
    Umea Univ, Sweden.
    Roothans, Jonas
    Medtronic, Sweden; Medtronic, Netherlands.
    Fytagoridis, Anders
    Umea Univ, Sweden; Karolinska Inst, Sweden.
    Ryzhkov, Maxim
    Medtronic, Sweden; Medtronic, Netherlands.
    Nijlunsing, Rutger
    Medtronic, Sweden; Medtronic, Netherlands.
    Blomstedt, Patric
    Umea Univ, Sweden.
    Prediction of Electrode Contacts for Clinically Effective Deep Brain Stimulation in Essential Tremor2018Inngår i: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 96, nr 5, s. 281-288Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background/Aim: Deep brain stimulation (DBS) is an established neurosurgical treatment that can be used to alleviate symptoms in essential tremor (ET) and other movement disorders. The aim was to develop a method and software tool for the prediction of effective DBS electrode contacts based on probabilistic stimulation maps (PSMs) in patients with ET treated with caudal zona incerta (cZi) DBS. Methods: A total of 33 patients (37 leads) treated with DBS were evaluated with the Essential Tremor Rating Scale (ETRS) 12 months after surgery. In addition, hand tremor and hand function (ETRS items 5/6 and 11-14) were evaluated for every contact during stimulation with best possible outcome without inducing side effects. Prediction of effective DBS electrode contacts was carried out in a retrospective leave-one-out manner based on PSMs, simulated stimulation fields, and a scoring function. Electrode contacts were ranked according to their likelihood of being included in the clinical setting. Ranked electrode contacts were compared to actual clinical settings. Results: Predictions made by the software tool showed that electrode contacts with rank 1 matched the clinically used contacts in 60% of the cases. Contacts with a rank of 1-2 and 1-3 matched the clinical contacts in 83 and 94% of the cases, respectively. Mean improvement of hand tremor and hand function was 79 +/- 21% and 77 +/- 22% for the clinically used and the predicted electrode contacts, respectively. Conclusions: Effective electrode contacts can be predicted based on PSMs in patients treated with cZi DBS for ET. Predictions may in the future be used to reduce the number of clinical assessments that are carried out before a satisfying stimulation setting is defined. (C) 2018 S. Karger AG, Basel

  • 2176.
    Åström, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Tisch, Stephen
    Institute of Neurology University College, London, UK.
    Zrinzo, Ludvic U.
    Institute of Neurology University College, London, UK.
    Tripoliti, Elina
    University of Neurology University College, London, UK.
    Hariz, Marwan I.
    Department of Neurosurgery University Hospital, Umeå, Sweden.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    A model-Based analysis of deep brain stimulation2007Konferansepaper (Annet vitenskapelig)
    Abstract [en]

      

  • 2177.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Tripoliti, E
    n/a.
    Hariz, M I
    n/a.
    Zrinzo, L U
    n/a.
    Martinez-Torre, I
    n/a.
    Limousin, P
    n/a.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Swedish Movement Disorder Society, Umeå 15-16 october, 20092009Inngår i: The electric field during DBS, 2009Konferansepaper (Annet vitenskapelig)
  • 2178.
    Åström, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Tripoliti, E.
    Institute of Neurology University College London.
    Zrinzo, U.
    Institute of Neurology University College London.
    Marinez-Torres, I.
    Institute of Neurology University College London.
    Limousin, P.
    Institute of Neurology University College London.
    Hariz, M. I.
    Institute of Neurology University College London.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Voltage steering to control deep brain stimulation-induced speech deficits2008Inngår i: XVIII Congress of the European Society for Stereotactic and Functional Neurosurgery,2008, 2008Konferansepaper (Annet vitenskapelig)
  • 2179.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Tripoliti, Elina
    University College, London.
    Hariz, Mawan I.
    University Hospital, Umeå .
    Zrinzo, Ludvig U.
    University College, London.
    Martinez-Torres, Irene
    University College, London.
    Limousin, Patricia
    University College, London.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation2010Inngår i: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 88, nr 4, s. 224-233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background/Aims: Deep brain stimulation (DBS) is widely used to treat motor symptoms in patients with advanced Parkinson’s disease. The aim of this study was to investigate the anatomical aspects of the electric field in relation to effects on speech and movement during DBS in the subthalamic nucleus. Methods: Patient-specific finite element models of DBS were developed for simulation of the electric field in 10 patients. In each patient, speech intelligibility and movement were assessed during 2 electrical settings, i.e. 4 V (high) and 2 V (low). The electric field was simulated for each electrical setting. Results: Movement was improved in all patients for both high and low electrical settings. In general, high-amplitude stimulation was more consistent in improving the motor scores than low-amplitude stimulation. In 6 cases, speech intelligibility was impaired during high-amplitude electrical settings. Stimulation of part of the fasciculus cerebellothalamicus from electrodes positioned medial and/or posterior to the center of the subthalamic nucleus was recognized as a possible cause of the stimulation-induced dysarthria. Conclusion: Special attention to stimulation-induced speech impairments should be taken in cases when active electrodes are positioned medial and/or posterior to the center of the subthalamic nucleus.

  • 2180.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Tripoliti, Elina
    Institute of Neurology, Queen Square, University College London, UK.
    Martinez-Torres, Irene
    Institute of Neurology, Queen Square, University College London, UK.
    Zrinzo, Ludvic U.
    Institute of Neurology, Queen Square, University College London, UK.
    Limousin, Patricia
    Institute of Neurology, Queen Square, University College London, UK.
    Hariz, Marwan I.
    Institute of Neurology, Queen Square, University College London, UK; Dept of Neurosurgery, University Hospital, Umeå, Sweden.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Patient-specific models and simulations of deep brain stimulation for postoperative follow-up2009Inngår i: World Congress on Medical Physics and Biomedical Engineering / [ed] Olaf Dössel and Wolfgang C. Schlegel, Springer , 2009, s. 331-334Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Deep brain stimulation (DBS) is an established treatment for Parkinson’s disease (PD). The success of DBS is highly dependent on electrode location and electrical parameter settings. In this study patient-specific computer models of DBS were used for postoperative follow-up in three PD patients who suffered from stimulation induced hypomania, dysarthria, and uncontrollable laughter respectively. The overall aim of the study was to relate the anatomical aspect of the electric field to the effects and side effects of stimulation. The simulations showed the anatomical distribution of the electric field for all the patients and the results were in agreement with previous reports regarding these side effects of stimulation. It was demonstrated that patient-specific models and simulations of DBS may be useful for postoperative follow-up of DBS.

  • 2181.
    Åström, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Tripoliti, Elina
    Institute of Neurology University College London, UK.
    Zrinzo, Ludvic U.
    Institute of Neurology University College London, UK.
    Martinez-Torres, Irene
    Institute of Neurology University College London, UK.
    Limousin, Patricia
    Institute of Neurology University College London, UK.
    Hariz, Marwan I.
    Institute of Neurology University College London, UK.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Voltage steering to control the effects and side effects of deep brain stimulation2008Konferansepaper (Annet vitenskapelig)
  • 2182.
    Åström, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Tripoliti, Elina
    Institute of Neurology University College, London, UK.
    Zrinzo, Ludvic U
    Institute of Neuroligy University College, London, UK.
    Tisch, Stephen
    Institute of Neurology University College, London, UK.
    Martinez-Torres, Irene
    Institute of Neurology University College, London, UK.
    Limousin, Patricia
    Institute of Neurology University College, London, UK.
    Hariz, Marwan I.
    Department of Neurosurgery University Hospital, Umeå, Sweden.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Effects of bilateral subthalamic nucleus deep brain stimulation on speech intelligibillity and movement: A model-based case stydy.2007Inngår i: XVII WFN World Congress on Parkinson´s disease and related disorders,2007, 2007Konferansepaper (Annet vitenskapelig)
    Abstract [en]

      

  • 2183.
    Åström, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    U. Zrinzo, Ludvic
    Institute of Neurology, Queen Square, London, UK.
    I. Hariz, Marwan
    Inst. för Neurokirurgi Norrlands universitetssjukhus, Umeå samt Institute of Neurology, Queen Square, London, UK.
    Tisch, Stephen
    Institute of Neurology, Queen Square, London, UK.
    Limousin, Patricia
    Institute of Neurology, Queen Square, London, UK.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Patientspecifik modellering och simulering av djup hjärnstimulering2006Inngår i: Medicinteknikdagarna 2006,2006, 2006Konferansepaper (Annet vitenskapelig)
  • 2184.
    Åström, Mattias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Zrinzo, L.U.
    Institute of Neurology Queen square, London, UK.
    Hariz, Marwan
    Institute of Neurology Queen square, London, UK.
    Tisch, Stephen
    Institute of Neurology Queen Square, London, UK.
    Limousin, Patricia
    Institute of Neurology Queens Square, London, UK.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Patient specific modelling and simulation of deep brain stimulation: A method for pre- and postoperative investigations2006Konferansepaper (Annet vitenskapelig)
  • 2185.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Zrinzo, Ludvic U
    University College London.
    Tisch, Stephen
    Linköpings universitet, Tekniska högskolan.
    Tripoliti, Elina
    University College London.
    Hariz, Marwan I
    University College London.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Method for patient-specific finite element modeling and simulation of deep brain stimulation2009Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 47, nr 1, s. 21-28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deep brain stimulation (DBS) is an established treatment for Parkinsons disease. Success of DBS is highly dependent on electrode location and electrical parameter settings. The aim of this study was to develop a general method for setting up patient-specific 3D computer models of DBS, based on magnetic resonance images, and to demonstrate the use of such models for assessing the position of the electrode contacts and the distribution of the electric field in relation to individual patient anatomy. A software tool was developed for creating finite element DBS-models. The electric field generated by DBS was simulated in one patient and the result was visualized with isolevels and glyphs. The result was evaluated and it corresponded well with reported effects and side effects of stimulation. It was demonstrated that patient-specific finite element models and simulations of DBS can be useful for increasing the understanding of the clinical outcome of DBS.

  • 2186.
    Öberg, Åke
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Bio-Optics in Medicine2003Inngår i: Medical & Biological Engineering & Computing, ISSN 0140-0118, Vol. 41, s. 241-241Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Guest editor

  • 2187.
    Öberg, Åke
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Medicinsk teknik i Japan1973Rapport (Annet (populærvitenskap, debatt, mm))
  • 2188.
    Öberg, Åke
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Optical sensors for heart- and respiratory rate measurements. Academic prototypes and clinical evaluation1996Inngår i: International Conference IEEE Engineering in Medicine and Biology Society,1996, IEEE , 1996Konferansepaper (Fagfellevurdert)
  • 2189.
    Öberg, Åke
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Optical sensors in medical care2004Inngår i: Sensors in Medicine and Health Care / [ed] Åke Öberg; Tatsuo Togawa and Francis A Spelman, Weinheim, Germany: WileyVCH Verlag , 2004, s. 15-44Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Due to remarkable developments in the field of sensors along with miniaturization, sophisticated microsensors are part of many aspects of 21st century medicine and health care. Turning sensory inputs of all kinds into defined electrical signals that can be  interpreted and acted upon by both stationary and portable medicne  equipment as well as implants, sensors find many applications monitoring blood pressure, heart rates, glucose levels and many other parameters by which human health can be evaluated.         

    They also serve as key components in modern imaging equipment as well as operating equipment for minimally invasive surgery,catheters and other applications.         

    Taken as a whole, Sensors Applications covers all major fields  of application for commercial sensors, as well as their  manufacturing techniques and major types. Strong emphasis is placedon microsensors, microsystems and integrated electronic sensor  packages rather than bulk equipment. Each of the individual volumes is tailored to the needs and queries of readers from the relevant branches of industry and research.

  • 2190.
    Öberg, Åke
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Optical sensors in Medical Care2004Inngår i: Sensors Update: sensor technology, applications, markets]. Vol. 13 / [ed] H. Baltes, G.K. Fedder, J.G. Korvink, Weinheim, Germany: WileyVCH Verlag , 2004, s. 201-232Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 2191.
    Öberg, Åke
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Tissue motion - a disturbance in the Laser-Doppler blood flow signal?1999Inngår i: Technology and Health Care, ISSN 0928-7329, Vol. 7, s. 185-192Artikkel i tidsskrift (Fagfellevurdert)
  • 2192.
    Öberg, Åke
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Salerud, Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Microprobes for blood flow measurements in tissue and small vessels1988Inngår i: SPIE Vol 94 Microsensors and Catheter-Based Imaging and Technology,1988, 1988, s. 35-Konferansepaper (Fagfellevurdert)
  • 2193.
    Öberg, Åke
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Spelman, Francis A.
    Dept. of Bioengineering University of Washington.
    Togawa, Tatsuo
    School of Human Sciences Waseda University.
    Introduction2004Inngår i: Sensors in Medicine and Health Care / [ed] P. Å. Öberg, Tatsuo Togawa, Francis A. Spelman, Weinheim, Germany: WileyVCH Verlag , 2004, s. -420Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Due to remarkable developments in the field of sensors along with miniaturization, sophisticated microsensors are part of many aspects of 21st century medicine and health care. Turning sensory inputs of all kinds into defined electrical signals that can be  interpreted and acted upon by both stationary and portable medicne  equipment as well as implants, sensors find many applications monitoring blood pressure, heart rates, glucose levels and many other parameters by which human health can be evaluated.        

    They also serve as key components in modern imaging equipment as well as operating equipment for minimally invasive surgery,catheters and other applications.        

    Taken as a whole, Sensors Applications covers all major fields  of application for commercial sensors, as well as their  manufacturing techniques and major types. Strong emphasis is placedon microsensors, microsystems and integrated electronic sensor  packages rather than bulk equipment. Each of the individual volumes is tailored to the needs and queries of readers from the relevant branches of industry and research.

  • 2194.
    Öberg, Åke
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Spelman, Francis A.
    Dept. of Bioengineering University of Washington, USA.
    Togawa, Tatsuo
    School of Human Sciences Waseda University.
    Sensors in Medicine and Health Care2004Bok (Annet vitenskapelig)
    Abstract [en]

    Due to remarkable developments in the field of sensors along with miniaturization, sophisticated microsensors are part of many aspects of 21st century medicine and health care. Turning sensory inputs of all kinds into defined electrical signals that can be  interpreted and acted upon by both stationary and portable medicne  equipment as well as implants, sensors find many applications monitoring blood pressure, heart rates, glucose levels and many other parameters by which human health can be evaluated.       

    They also serve as key components in modern imaging equipment as well as operating equipment for minimally invasive surgery,catheters and other applications.       

    Taken as a whole, Sensors Applications covers all major fields  of application for commercial sensors, as well as their  manufacturing techniques and major types. Strong emphasis is placedon microsensors, microsystems and integrated electronic sensor  packages rather than bulk equipment. Each of the individual volumes is tailored to the needs and queries of readers from the relevant branches of industry and research.

  • 2195.
    Öberg, Åke
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Sundqvist, Tommy
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för molekylär och klinisk medicin, Medicinsk mikrobiologi.
    Johansson, Anders
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Assessment of cartilage thickness utilising reflectance spectroscopy2004Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 42, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new principle for cartilage layer thickness assessments in joints is presented. It is based on the differences between the absorption spectra of cartilage and subchondral bone (containing blood). High-resolution ultrasound measurements of cartilage thickness were compared with reflection spectroscopy data from the same area of bovine hip joint condyles. A simple mathematical model allowed calculation of thickness and comparison with ultrasound data. The cartilage thickness was changed by being ground in short episodes. For thicker cartilage layers, a high degree of reflection in the 400-600nm wavelength interval was seen. For thinner cartilage layers, the characteristics of the spectra of blood and bone dominated those of cartilage. The mean (±SD) thickness of intact cartilage was 1.21± 0.30 mm (n = 30). In an exponential regression model, spectroscopic estimation of cartilage thickness showed a correlation coefficient of r= 0.69 (n = 182). For thinner cartilage layers (d<0.5mm), the mean model error was 0.19±0.17mm. Results from a bi-layer Monte Carlo simulation supported the assumption of an exponential relationship between spectroscopy data and reference ultrasound data. The conclusion is that optical reflection spectroscopy can be used for cartilage layer thickness assessment.

  • 2196.
    Öberg, Åke
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Sundqvist, Tommy
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för molekylär och klinisk medicin, Medicinsk mikrobiologi.
    Johansson, Anders
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Sundberg, Mikael
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Characterisation of the cartilage/bone interface utilising reflectance spectroscopy2001Inngår i: 23rd Annual International Conference IEEE EMBS,2001, IEEE , 2001, Vol. 3, s. 3002-3004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Optical reflection spectra of the cartilage/bone interface from hip joints of cows were studied. When comparing to ultrasonic measurement, it was found that cartilage thickness could be extracted using optical reflectance spectroscopy. For thicker cartilage layers, a high reflection for the wavelengths 400-600 nm was seen, and for thinner cartilage layers, the characteristic spectra of blood and bone dominated. The optical reflectance spectra may be used to characterise cartilage, and specifically cartilage thickness, in connection with in situ diagnosis or autologous chondrocyte implantation (ACI).

  • 2197.
    Öberg, Åke
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Tamura, T.
    Lindberg, Lars-Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Salerud, Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    A comparison between laser Doppler flowmetry and photoplethysmography1988Inngår i: Betch. AMH CCCP,1988, 1988, s. 82-Konferansepaper (Fagfellevurdert)
  • 2198.
    Ödman, Svante
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    On biomedical electrode technology: with special reference to long-term properties and movement-induced noise in surface electrodes1980Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of the present investigation was to improve the quality of surface electrode measurements. Long-term properties of commercially available ECG-electrodes were studied by investigating polarization potentials, electrode impedance, adhesion and skin reactions during a period of 7 days. The most stable polarization potentials were obtained for Ag/AgC1-electrodes and stable electrode impedance were obtained for disposable electrodes with stable adhesion and equipped with an electrode capsule. Unchanged adhesion and mechanical strength were shown by disposable electrodes with large self-adhesive collars.

    Movement-induced potentials of streaming potential type were studied in various electrode configurations. The geometric design of the electrode was important for reduction of noise generated by the movement of gel. Potential and impedance variations were measured for electrode movements in electrolytes relative to the skin. The impedance variations were small and streaming potentials with a magnitude of up to 10μV were recorded. The deformation potentials generated in the skin dominate the disturbance pattern in surface electrode recordings. Potential and impedance variations studied with varying mechanical stress upon skin showed that the impedance variations did not bring about the potential variations. The size of potential variations in skin and related mechanical stress possess a non-linear relationship which varies between individuals. A non-linear character of the time sequence of stretch potentials was found.

    The spread of deformation potentials was studied in the skin area around and beneath surface electrodes. When stretching a rectangular skin zone between two plates fixed to the skin the highest potentials were obtained in the zone. The magnitude of the potentials decreased with the distance to the zone. Stretch potentials could be reduced but not geometrically limited by fixing the skin to a rigid electrode collar. The potential spread is a consequence of successively decreasing deformation.

  • 2199. Ödman, Svante
    et al.
    Levitan, Herbert
    Robinson, Peter J
    Michel, Mary Ellen
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Rapoport, Santley I
    Peripheral nerve as an osmometer: role of endoneurial capillaries in frog sciatic nerve.1987Inngår i: American Journal of Physiology, ISSN 0002-9513, E-ISSN 2163-5773, Vol. 252, nr 3 Pt 1, s. C335-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The sciatic nerve of the frog was perfused in vivo with isotonic Ringer solution followed by Ringer made hypertonic by addition of sucrose or of NaCl. Nerve diameter and endoneurial hydrostatic pressure fell during hypertonic Ringer perfusion. Using a model that describes the elastic and osmotic properties of the nerve, sigma sLp, the product of the osmotic reflection coefficient at endoneurial capillaries for s equals sucrose or NaCl (which approximates 1), and of capillary hydraulic conductivity, was found to equal 73 X 10(-13) cm3 X s-1 X dyn-1. The nerve is elastic. It has a compliance K of 3.7 X 10(-5) cm2 X mmHg-1, corresponding to a modulus of elasticity E of the perineurium equal to 1.2 X 10(6) dyn X cm-2. The results indicate that the nerve behaves as an osmometer during vascular perfusion, due to the low permeability of endoneurial capillaries to small solutes such as NaCl and sucrose. A low capillary hydraulic conductivity limits bulk water flow between blood and nerve, and a low compliance limits nerve swelling and edema.

  • 2200.
    Öhman, Fredrik
    Linköpings universitet, Institutionen för medicinsk teknik.
    Går det att mäta blodtryck med fotopletysmografi och bioakustisk sensor i kombination?2004Independent thesis Basic level (professional degree)Oppgave
    Abstract [sv]

    The aim of the work was to investigate the possibility to combine information from PPG and bio-acoustic technology to extract information that is related to the blood pressure. The measurements have been carried out with several different configurations. First the relation between arterial sounds and the PPG-signal was studied. After those measurements with both PPG and the bio- acoustic technique was concluded on people in different positions and after riding a bike. The goal was to vary the blood pressure. The conclusion that can be drawn in this report is that the bio-acoustic and the PPG-signal in peripheral arteries have the same source. That implies that arterial sounds are a product of turbulence when the pulse wave passes by. Further it can be assumed that it is the first heart sound that is represented in the arterial sounds. The time before and after the arterial sound in one heart cycle vary whit the blood pressure. There relationship seems also to vary with the bloodpressure but it vary differently under different conditions.

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