liu.seSearch for publications in DiVA
Endre søk
Begrens søket
567891011 351 - 400 of 2207
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 351.
    Chowdhury, Shamsul I.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Computer-based support for knowledge extraction from clinical databases1990Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is devoted to aspects related to the analysis and interpretation of medical data thus allowing knowledge extraction from medical databases. The difficulties with traditional approaches for data analysis and interpretation by people less proficient in statistics are well known. An attempt has been made to identify different stages in the processes of data analysis and interpretation where this category of users might need help and to identify how this help could best be provided (studies I, II, III). In this work artificial intelligence approaches have been used as remedies to improve user-friendliness as well as power and effectiveness of statistical software in respect to data analysis strategies. Prototype implementations based on these approaches are presented and discussed. Issues pertaining to the evaluation of decision support systems m medicine have been identified and discussed in detail (study IV).

    Knowledge in a knowledge-based system for decision support is generally acquired from experts and the literature. Knowledge can also be effectively extracted from a database of patient observations and from interpretation of those observations. The resulting system would be more accurate in the latter case, especially if it is intended to operate in decision support in the same clinical setting.

    The studies V and VI were conducted to show how retrospectively collected data could be utilized for the purpose of knowledge extraction. More traditional data analysis approaches (study V) were used to analyze a database on liver diseases. The data material used in the study was collected in the HELP system as a routine part of patient care. The main issues involved were detection of outliers and treatment of missing values in order to facilitate utilization of this kind of database for eventual knowledge extraction. In Study V, statistical techniques including discriminant analysis and artificial intelligence approaches such asinductive learning, were used. The 'K nearest neighbor' technique was found to be an easy and acceptable method for estimating missing values when the database contained only a few missing values for each object in the database. Discriminant analysis was found to be a good method for classifying a patient, based on a set of variables, into two or more disease classes. The results show that when discriminant analysis was applied to two groups based on a relatively large number (19) of variables, then only a few (3) of the variables accounted for a high percentage of correct classifications.

    The knowledge-based approach for data analysis and interpretation used in (study III) was applied to a large database (study VI). The main emphasis was to study the feasibility of the approach in exploring a large patient record system. The data material was taken from Kronan Health Center - a primary health care center in suburban Stockholm with a patient database consisting of about 14,000 medical records. The analysis was carried out to test the hypothesis of a possible causation between hypertension and diabetes. The results of this study support the assumption that there is a relationship between diabetes and hypertension but the question of the direction of this relationship remained unsolved, as did the question of direct causality. On the other hand, the results of this study are in accordance with the hypothesis of a common metabolic syndrome. The results arrived at by the analysis method (multivariate tabular analysis) utilized by the system are, moreover in accordance with another statistical method (log linear analysis). This also supports the approach taken in the knowledge-based system.

  • 352.
    Chowdhury, Shamsul
    et al.
    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.
    Wallgren, Anders
    Dept of Statistics Sween Örebro.
    Wallgren, Britt
    Dept Statistics Sweden Örebro.
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Extracting knowledge from a large primary health care database using a knowledge-based statistical approach1990Inngår i: Journal of medical systems, ISSN 0148-5598, E-ISSN 1573-689X, Vol. 14, nr 4, s. 213-225Artikkel i tidsskrift (Fagfellevurdert)
  • 353.
    Chowdhury, Shamsul
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Mathiesen, Ulrik
    Oskarshamns sjukhus .
    Krusinska, Ewa
    Technical University of Wroclaw, Poland .
    Franzén, Lennart
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Patologi. Östergötlands Läns Landsting, Laboratoriemedicinskt centrum, Klinisk patologi och klinisk genetik.
    Wigertz, Ove
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Bodemar, Göran
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för molekylär och klinisk medicin, Gastroenterologi och hepatologi. Östergötlands Läns Landsting, Medicincentrum, Endokrin- och magtarmmedicinska kliniken US.
    Design and delivery of information resources and knowledge bases for the diagnosis and managementof liver disorders1994Inngår i: ANZIIS-94,1994, Brisbane: IEEE , 1994Konferansepaper (Fagfellevurdert)
  • 354.
    Chowdhury, Shamsul
    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.
    Artificial Intelligence methods in data analysis and interpretation1990Inngår i: Knowledge, Data and Computer-assisted Decisions / [ed] Martin Schader, Wolfgang Gaul, Berlin: Springer Verlag , 1990, s. 199-208Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 355.
    Chowdhury, Shamsul
    et al.
    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.
    Sundgren, Bo
    Stockholm School of Econimics .
    A knowledge-based system for data analysis and interpretation1989Inngår i: Methods of Information in Medicine, ISSN 0026-1270, Vol. 28Artikkel i tidsskrift (Fagfellevurdert)
  • 356.
    Cieslar-Pobuda, Artur
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för cellbiologi. Linköpings universitet, Hälsouniversitetet.
    Bäck, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska högskolan.
    Magnusson, Karin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska högskolan.
    Vilas Jain, Mayur
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för cellbiologi. Linköpings universitet, Hälsouniversitetet.
    Rafat, Mehrdad
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Hälsouniversitetet.
    Ghavami, Saeid
    Manitoba Institute Child Heatlh, Canada; University of Manitoba, Canada .
    Nilsson, Peter R.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska högskolan.
    Los, Marek Jan
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för cellbiologi. Linköpings universitet, Hälsouniversitetet.
    Cell Type Related Differences in Staining with Pentameric Thiophene Derivatives2014Inngår i: Cytometry Part A, ISSN 1552-4922, E-ISSN 1552-4930, Vol. 85A, nr 7, s. 628-635Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fluorescent compounds capable of staining cells selectively without affecting their viability are gaining importance in biology and medicine. Recently, a new family of optical dyes, denoted luminescent conjugated oligothiophenes (LCOs), has emerged as an interesting class of highly emissive molecules for studying various biological phenomena. Properly functionalized LCOs have been utilized for selective identification of disease-associated protein aggregates and for selective detection of distinct cells. Herein, we present data on differential staining of various cell types, including cancer cells. The differential staining observed with newly developed pentameric LCOs is attributed to distinct side chain functionalities along the thiophene backbone. Employing flow cytometry and fluorescence microscopy we examined a library of LCOs for stainability of a variety of cell lines. Among tested dyes we found promising candidates that showed strong or moderate capability to stain cells to different extent, depending on target cells. Hence, LCOs with diverse imidazole motifs along the thiophene backbone were identified as an interesting class of agents for staining of cancer cells, whereas LCOs with other amino acid side chains along the backbone showed a complete lack of staining for the cells included in the study. Furthermore, for p-HTMI,a LCO functionalized with methylated imidazole moieties, the staining was dependent on the p53 status of the cells, indicating that the molecular target for the dye is a cellular component regulated by p53. We foresee that functionalized LCOs will serve as a new class of optical ligands for fluorescent classification of cells and expand the toolbox of reagents for fluorescent live imaging of different cells.

  • 357.
    Cirillo, Marco Domenico
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Mirdell, Robin
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Pham, Tuan
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Tensor Decomposition for Colour Image Segmentation of Burn Wounds2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikkel-id 3291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Research in burns has been a continuing demand over the past few decades, and important advancements are still needed to facilitate more effective patient stabilization and reduce mortality rate. Burn wound assessment, which is an important task for surgical management, largely depends on the accuracy of burn area and burn depth estimates. Automated quantification of these burn parameters plays an essential role for reducing these estimate errors conventionally carried out by clinicians. The task for automated burn area calculation is known as image segmentation. In this paper, a new segmentation method for burn wound images is proposed. The proposed methods utilizes a method of tensor decomposition of colour images, based on which effective texture features can be extracted for classification. Experimental results showed that the proposed method outperforms other methods not only in terms of segmentation accuracy but also computational speed.

  • 358.
    Cirillo, Marco Domenico
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Mirdell, Robin
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Pham, Tuan
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Time-Independent Prediction of Burn Depth using Deep Convolutional Neural Networks2019Inngår i: Journal of Burn Care & Research, ISSN 1559-047X, E-ISSN 1559-0488, Vol. 40, nr 6, s. 857-863Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present in this paper the application of deep convolutional neural networks, which are a state-of-the-art artificial intelligence (AI) approach in machine learning, for automated time-independent prediction of burn depth. Colour images of four types of burn depth injured in first few days, including normal skin and background, acquired by a TiVi camera were trained and tested with four pre-trained deep convolutional neural networks: VGG-16, GoogleNet, ResNet-50, and ResNet-101. In the end, the best 10-fold cross-validation results obtained from ResNet- 101 with an average, minimum, and maximum accuracy are 81.66%, 72.06% and 88.06%, respectively; and the average accuracy, sensitivity and specificity for the four different types of burn depth are 90.54%, 74.35% and 94.25%, respectively. The accuracy was compared to the clinical diagnosis obtained after the wound had healed. Hence, application of AI is very promising for prediction of burn depth and therefore can be a useful tool to help in guiding clinical decision and initial treatment of burn wounds.

    Fulltekst tilgjengelig fra 2020-06-11 08:35
  • 359.
    Claesson, Fredrik
    et al.
    Flodafors Lego AB.
    Andersson, Roger
    Katrineholms kommun.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    CeMIDCARE - Kunskapscentrum för medicinsk teknik och innovationer inom distribuerad närvård.2006Konferansepaper (Annet vitenskapelig)
  • 360. Clancy, N.
    et al.
    Leahy, MJ.
    Nilsson, Gert
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Anderson, Chris
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för biomedicin och kirurgi, Avdelningen för dermatologi och venereologi. Östergötlands Läns Landsting, Medicincentrum, Hudkliniken i Östergötland.
    Non-invasive assessment of the mechanical properties of human skin - investigation of effective age using an optical method2006Inngår i: Royal Academy of Medicine in Ireland, Section of Biomedical Sciences, University of Limerick, Summer Meeting,2006, 2006Konferansepaper (Fagfellevurdert)
  • 361.
    Clancy, Neil T.
    et al.
    Department of Physics, University of Limerick, Ireland.
    Leahy, Martin J.
    Department of Physics, University of Limerick, Ireland.
    Nilsson, Gert
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Anderson, Chris
    Linköpings universitet, Institutionen för biomedicin och kirurgi, Avdelningen för dermatologi och venereologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Medicincentrum, Hudkliniken i Östergötland.
    Analysis of skin recovery from mechanical indentation using diffuse lighting and digital imaging2007Inngår i: Diffuse Optical Imaging of Tissue / [ed] Brian W. Pogue; Rinaldo Cubeddu, SPIE - International Society for Optical Engineering, 2007, s. 66291G-1-66291G-10Konferansepaper (Annet vitenskapelig)
    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.

  • 362.
    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.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Anderson, Chris
    Linköpings universitet, Institutionen för biomedicin och kirurgi, Avdelningen för dermatologi och venereologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Medicincentrum, Hudkliniken i Östergötland.
    Analysis of skin recovery from mechanical indentation using diffuse lighting and digital imaging. in Diffuse Optical Imaging of Tissue.2007Inngår i: 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, s. 66291G-1-66291G-10Konferansepaper (Fagfellevurdert)
    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.

  • 363.
    Clancy, Neil T
    et al.
    University of London Imperial College of Science, Technology and Medicine.
    Nilsson, Gert
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Anderson, Chris
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Dermatologi och venerologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Medicincentrum, Hudkliniken i Östergötland.
    Leahy, Martin J
    University of Limerick.
    A new device for assessing changes in skin viscoelasticity using indentation and optical measurement2010Inngår i: SKIN RESEARCH AND TECHNOLOGY, ISSN 0909-752X, Vol. 16, nr 2, s. 210-228Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 364. Clancy, NT.
    et al.
    Leahy, MJ.
    Nilsson, Gert
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Non-invasive assessment of the mechanical properties of human skin - investigation of effective age using an optical method2006Inngår i: BioMed 2006,2006, 2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

      

  • 365. Clancy, NT.
    et al.
    Leahy, MJ.
    Nilsson, Gert
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Anderson, Chris
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för biomedicin och kirurgi, Avdelningen för dermatologi och venereologi. Östergötlands Läns Landsting, Medicincentrum, Hudkliniken i Östergötland.
    Analysis of mechanical imprints in human skin using an optical technique. in Fission Impossible?2007Inngår i: IOPI Spring Weekend Meeting,2007, 2007Konferansepaper (Fagfellevurdert)
  • 366.
    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
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Strömberg, Tomas
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    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 RISK2015Inngår i: 2015 INTERNATIONAL WORKSHOP ON COMPUTATIONAL INTELLIGENCE FOR MULTIMEDIA UNDERSTANDING (IWCIM), IEEE , 2015Konferansepaper (Fagfellevurdert)
    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.

  • 367.
    Collste, Göran
    et al.
    Linköpings universitet, Filosofiska fakulteten. Linköpings universitet, Institutionen för religion och kultur, Centrum för tillämpad etik.
    Shahsavar, Nosrat
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    Gill, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    A decision support system for diabetes care: Ethical aspects1999Inngår i: Methods of Information in Medicine, ISSN 0026-1270, Vol. 38, s. 313-316Artikkel i tidsskrift (Fagfellevurdert)
  • 368.
    Cornet, Ronald
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Univ Amsterdam, Netherlands.
    Infrastructure and Capacity Building for Semantic Interoperability in Healthcare in the Netherlands2017Inngår i: BUILDING CAPACITY FOR HEALTH INFORMATICS IN THE FUTURE, IOS PRESS , 2017, Vol. 234, s. 70-74Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Over 15 years, a broad spectrum of activities was undertaken to realize a health IT infrastructure in the Netherlands. In this paper we reflect on the history, challenges, accomplishments, changes, and the way forward. It shows that the infrastructure depends on technical, legal, and semantic aspects, which are frequently reciprocally related. It also highlights the fact that the role of health professionals and of patients is increasingly considered as a crucial element.

  • 369.
    Cornet, Ronald
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Dentler, Kathrin
    Dept. of Computer Science, VU University Amsterdam, The Netherlands and Dept. of Medical Informatics, Academic Medical Center, University of Amsterdam, The Netherlands.
    Redundant Elements in SNOMED CT Concept Definitions2013Inngår i: proceedings of AIME 2013, Lecture Notes in ComputerScience 2013, Vol. 7885 / [ed] Peek, Niels, Marín Morales, Roque Luis, Peleg, Mor, Springer , 2013, s. 186-195Konferansepaper (Fagfellevurdert)
    Abstract [en]

    While redundant elements in SNOMED CT concept definitions are harmless from a logical point of view, they unnecessarily make concept definitions of typically large ontologies such as SNOMED CT hard to construct and to maintain. In this paper, we apply a fully automated method to detect intra-axiom redundancies in SNOMED CT. We systematically analyse the completeness and soundness of the results of our method by examining the identified redundant elements. In absence of a gold standard, we check whether our method identifies concepts that are likely to contain redundant elements because they become equivalent to their stated subsumer when they are replaced by a fully defined concept with the same definition. To evaluate soundness, we remove all identified redundancies, and test whether the logical closure is preserved by comparing the concept hierarchy to the one of the official SNOMED CT distribution. We found that 35,010 of the 296,433 SNOMED CT concepts (12%) contain redundant elements in their definitions, and that the results of our method are sound and complete with respect to our partial evaluation. We recommend to free the stated form from these redundancies. In future, knowledge modellers should be supported by being pointed to newly introduced redundancies.

  • 370.
    Cornet, Ronald
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Univ Amsterdam, Netherlands.
    Hill, Carly
    Univ Amsterdam, Netherlands.
    de Keizer, Nicolette
    Univ Amsterdam, Netherlands.
    Comparison of Three English-to-Dutch Machine Translations of SNOMED CT Procedures2017Inngår i: MEDINFO 2017: PRECISION HEALTHCARE THROUGH INFORMATICS, IOS PRESS , 2017, Vol. 245, s. 848-852Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Dutch interface terminologies are needed to use SNOMED CT in the Netherlands. Machine translation may support in their creation. The aim of our study is to compare different machine translations of procedures in SNOMED CT. Procedures were translated using Google Translate, Matecat, and Thot. Google Translate and Matecat are tools with large but general translation memories. The translation memory of Thot was trained and tuned with various configurations of a Dutch translation of parts of SNOMED CT, a medical dictionary and parts of the UMLS Metathesaurus. The configuration with the highest BLEU score, representing closeness to human translation, was selected. Similarity was determined between Thot translations and those by Google and Matecat. The validity of translations was assessed through random samples. Google and Matecat translated similarly in 85.4% of the cases and generally better than Thot. Whereas the quality of translations was considered acceptable, machine translations alone are yet insufficient.

  • 371.
    Cornet, Ronald
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. University of Amsterdam, The Netherlands.
    Nyström, Mikael
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Karlsson, Daniel
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik.
    User-Directed Coordination in SNOMED CT2013Inngår i: MedInfo 2013: Proceedings of the 14th World Congress on Medical and Health Informatics / [ed] Lehmann, C.U., Ammenwerth, E., Nøhr, C., Amsterdam: IOS Press, 2013, s. 72-76Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The possibility of post-coordination of SNOMED CT concepts, especially by clinical users, is both an asset and a challenge for SNOMED CT implementation. To get insight in the applicability of post-coordination, we analyzed scenarios for user-directed coordination that are described in the documentation of SNOMED CT. The analyses were based on experiences from previous and ongoing research and implementation work, including national mapping projects, and investigations on collection of data for multiple uses. These scenarios show various usability and representation problems: high number of relationships for refinement and qualification, improper options for refinement, incorrect formal definitions, and lack of support for applying editorial rules. Improved user-directed coordination in SNOMED CT in real practice requires advanced sanctioning, increased consistency of definitions of concepts in SNOMED CT, and real-time analysis of the post-coordinate expression.

  • 372.
    Cros, Olivier
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Image Analysis and Visualization of the Human Mastoid Air Cell System2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    From an engineering background, it is often believed that the human anatomy has already been fully described. Radiology has greatly contributed to understand the inside of the human body without surgical intervention. Despite great advances in clinical CT scanning, image quality is still related to a limited amount X-ray exposure for the patient safety. This limitation prevents fine anatomical structures to be visible and, more importantly, to be detected. Where such modality is of great advantage for screening patients, extracting parameters like surface area and volume implies the bone structure to be large enough in relation to the scan resolution.

    The mastoid, located in the temporal bone, houses an air cell system whose cells have a variation in size that can go far below current conventional clinical CT scanner resolution. Therefore, the mastoid air cell system is only partially represented on a CT scan. Any statistical analysis will be biased towards air cells of smaller size. To allow a complete representation of the mastoid air cell system, a micro-CT scanner is more adequate. Micro-CT scanning uses approximately the same amount of X-rays but for a much longer exposure time compared to what is normally allowed for patients. Human temporal bone specimens are therefore necessary when using such scanning method. Where the conventional clinical CT scanner lacks level of minutes details, micro-CT scanning provides an overwhelming amount of fine details.

    Prior to any image analysis of medical data, visualization of the data is often needed to learn how to extract the structures of interest for further processing. Visualization of micro-CT scans is of no exception. Due to the high resolution nature of the data, visualization of such data not only requires modern and powerful computers, but also necessitates a tremendous amount of time to adjust the hiding of irrelevant structures, to find the correct orientation, while emphasising the structure of interest. Once the quality of the data has been assessed, and a strategy for the image processing has been decided, the image processing can start, to in turn extract metrics such as the surface area or volume and draw statistics from it. The temporal bone being one of the most complex in the human body, visualization of micro-CT scanning of this bone awakens the curiosity of the experimenter, especially with the correct visualization settings.

    This thesis first presents a statistical analysis determining the surface area to volume ratio of the mastoid air cell system of human temporal bone, from micro-CT scanning using methods previously applied for conventional clinical CT scannings. The study compared current resul s with previous studies, with successive downsampling the data down to a resolution found in conventional clinical CT scanning. The results from the statistical analysis showed that all the small mastoid air cells, that cannot be detected in conventional clinical CT scans, do heavily contribute to the estimation of the surface area, and in consequence to the estimation of the surface area to volume ratio by a factor of about 2.6. Such a result further strengthens the idea of the mastoid to play an active role in pressure regulation and gas exchange.

    Discovery of micro-channels through specific use of a non-traditional transfer function was then reported, where a qualitative and a quantitative preanalysis was performed are described. To gain more knowledge about these micro-channels, a local structure tensor analysis was applied where structures are described in terms of planar, tubular, or isotropic structures. The results from this structural tensor analysis, also reported in this thesis, suggest these micro-channels to potentially be part of a more complex framework, which hypothetically would provide a separate blood supply for the mucosa lining the mastoid air cell system.

    Delarbeid
    1. Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bone: Geometrical parameters dependence on scanning resolutions
    Åpne denne publikasjonen i ny fane eller vindu >>Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bone: Geometrical parameters dependence on scanning resolutions
    Vise andre…
    2016 (engelsk)Inngår i: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 340, s. 127-134Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. Thus, these geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA than the V, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.

    Our aim was to determine the SA, V, and SA/V ratio in MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.

    The mean SA was 194 cm2, the mean V was 9 cm3, and the mean SA/V amounted to 22 cm-1. Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.

    The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a separate role of the MACS compared with the tympanum, and the results are important for a more accurate modeling of the middle ear physiology.

    Emneord
    Mastoid air cells; medical imaging; micro-CT; surface area; volume
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-122176 (URN)10.1016/j.heares.2015.12.005 (DOI)000386417900016 ()
    Tilgjengelig fra: 2015-10-23 Laget: 2015-10-23 Sist oppdatert: 2019-12-02bibliografisk kontrollert
    2. Micro CT-scanning of the mastoid. Micro-channels supporting a high vascular supply of the mastoid mucosa and its role in pressure regulation
    Åpne denne publikasjonen i ny fane eller vindu >>Micro CT-scanning of the mastoid. Micro-channels supporting a high vascular supply of the mastoid mucosa and its role in pressure regulation
    Vise andre…
    2013 (engelsk)Konferansepaper, Oral presentation only (Annet vitenskapelig)
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-101199 (URN)
    Konferanse
    1st Global Otology Research Forum, 13 Novenber 2013, Antalya, Turkey
    Tilgjengelig fra: 2013-11-20 Laget: 2013-11-20 Sist oppdatert: 2018-09-11
    3. Structural Analysis of Micro-channels in Human Temporal Bone
    Åpne denne publikasjonen i ny fane eller vindu >>Structural Analysis of Micro-channels in Human Temporal Bone
    2015 (engelsk)Inngår i: IEEE 12th International Symposium on Biomedical Imaging (ISBI), 2015 IEEE 12th International Symposium on, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 9-12Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Recently, numerous micro-channels have been discovered in the human temporal bone by micro-CT-scanning. Preliminary structure of these channels has suggested they contain a new separate blood supply for the mucosa of the mastoid air cells, which may have important functional implications. This paper proposes a structural analysis of the microchannels to corroborate this role. A local structure tensor is first estimated. The eigenvalues obtained from the estimated local structure tensor were then used to build probability maps representing planar, tubular, and isotropic tensor types. Each tensor type was assigned a respective RGB color and the full structure tensor was rendered along with the original data. Such structural analysis provides new and relevant information about the micro-channels but also their connections to mastoid air cells. Before carrying a future statistical analysis, a more accurate representation of the micro-channels in terms of local structure tensor analysis using adaptive filtering is needed.

    sted, utgiver, år, opplag, sider
    Institute of Electrical and Electronics Engineers (IEEE), 2015
    Serie
    IEEE International Symposium on Biomedical Imaging, ISSN 1945-7928
    Emneord
    Human temporal bone, mastoid, microchannels, quadrature filters, structure tensor, visualization
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-122177 (URN)10.1109/ISBI.2015.7163804 (DOI)000380546000003 ()978-1-4799-2374-8 (ISBN)
    Konferanse
    IEEE 12th International Symposium on Biomedical Imaging (ISBI), 2015 IEEE 12th International Symposium on, 16-19 April, New York, USA
    Tilgjengelig fra: 2015-10-23 Laget: 2015-10-23 Sist oppdatert: 2017-05-10bibliografisk kontrollert
  • 373.
    Cros, Olivier
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Structural properties of the mastoid using image analysis and visualization2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The mastoid, located in the temporal bone, houses an air cell system whose cells have a variation in size that can go far below current conventional clinical CT scanner resolution. Therefore, the mastoid air cell system is only partially represented in a CT scan. Where the conventional clinical CT scanner lacks level of minute details, micro-CT scanning provides an overwhelming amount of ne details. The temporal bone being one of the most complex in the human body, visualization of micro-CT scanning of this boneawakens the curiosity of the experimenter, especially with the correct visualization settings.

    This thesis first presents a statistical analysis determining the surface area to volume ratio of the mastoid air cell system of human temporal bone, from micro-CT scanning using methods previously applied for conventional clinical CT scans. The study compared current results with previous studies, with successive downsampling the data down to a resolution found in conventional clinical CT scanning. The results from the statistical analysis showed that all the small mastoid air cells, that cannot be detected in conventional clinical CT scans, do heavily contribute to the estimation of the surface area, and in consequence to the estimation of the surface area to volume ratio by a factor of about 2.6. Such a result further strengthens the idea of the mastoid to play an active role in pressure regulation and gas exchange.

    Discovery of micro-channels through specific use of a non-traditional transfer function was then reported, where a qualitative and a quantitative pre-analysis were performed and reported. To gain more knowledge about these micro-channels, a local structure tensor analysis was applied where structures are described in terms of planar, tubular, or isotropic structures. The results from this structural tensor analysis suggest these microchannels to potentially be part of a more complex framework, which hypothetically would provide a separate blood supply for the mucosa lining the mastoid air cell system.

    The knowledge gained from analysing the micro-channels as locally providing blood to the mucosa, led to the consideration of how inflammation of the mucosa could impact the pneumatization of the mastoid air cell system. Though very primitive, a 3D shape analysis of the mastoid air cell system was carried out. The mastoid air cell system was first represented in a compact form through a medial axis, from which medial balls could be used. The medial balls, representative of how large the mastoid air cells can be locally, were used in two complementary clustering methods, one based on the size diameter of the medial balls and one based on their location within the mastoid air cell system. From both quantitative and qualitative statistics, it was possible to map the clusters based on pre-defined regions already described in the literature, which opened the door for new hypotheses concerning the effect of mucosal inflammation on the mastoid pneumatization.

    Last but not least, discovery of other structures, previously unreported in the literature, were also visually observed and briefly discussed in this thesis. Further analysis of these unknown structures is needed.

    Delarbeid
    1. Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bone: Geometrical parameters dependence on scanning resolutions
    Åpne denne publikasjonen i ny fane eller vindu >>Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bone: Geometrical parameters dependence on scanning resolutions
    Vise andre…
    2016 (engelsk)Inngår i: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 340, s. 127-134Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. Thus, these geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA than the V, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.

    Our aim was to determine the SA, V, and SA/V ratio in MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.

    The mean SA was 194 cm2, the mean V was 9 cm3, and the mean SA/V amounted to 22 cm-1. Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.

    The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a separate role of the MACS compared with the tympanum, and the results are important for a more accurate modeling of the middle ear physiology.

    Emneord
    Mastoid air cells; medical imaging; micro-CT; surface area; volume
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-122176 (URN)10.1016/j.heares.2015.12.005 (DOI)000386417900016 ()
    Tilgjengelig fra: 2015-10-23 Laget: 2015-10-23 Sist oppdatert: 2019-12-02bibliografisk kontrollert
    2. Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning
    Åpne denne publikasjonen i ny fane eller vindu >>Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning
    Vise andre…
    2013 (engelsk)Inngår i: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 301, s. 60-65Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The mastoid air cell system has traditionally been considered to have a passive role in gas exchange and pressure regulation of the middle ear possibly with some acoustic function. However, more evidence has focused on the mucosa of the mastoid, which may play a more active role in regulation of middle ear pressure.

    In this study we have applied micro-CT scanning on a series of three human temporal bones. This approach greatly enhances the resolution (40–60 μm), so that we have discovered anatomical details, which has not been reported earlier. Thus, qualitative analysis using volume rendering has demonstrated notable micro-channels connecting the surface of the compact bone directly to the mastoid air cells as well as forming a network of connections between the air cells. Quantitative analysis on 2D slices was employed to determine the average diameter of these micro-channels (158 μm; range = 40–440 μm) as well as their density at a localized area (average = 75 cm−2; range = 64–97 cm−2).

    These channels are hypothesized to contain a separate vascular supply for the mastoid mucosa. However, future studies of the histological structure of the micro-channels are warranted to confirm the hypothesis. Studies on the mastoid mucosa and its blood supply may improve our knowledge of its physiological properties, which may have important implications for our understanding of the pressure regulation of the middle ear.

    sted, utgiver, år, opplag, sider
    Elsevier, 2013
    Emneord
    mastoid, micro CT, middle ear
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-92813 (URN)10.1016/j.heares.2013.03.002 (DOI)000320478100009 ()23518400 (PubMedID)
    Tilgjengelig fra: 2013-05-22 Laget: 2013-05-22 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    3. Structural Analysis of Micro-channels in Human Temporal Bone
    Åpne denne publikasjonen i ny fane eller vindu >>Structural Analysis of Micro-channels in Human Temporal Bone
    2015 (engelsk)Inngår i: IEEE 12th International Symposium on Biomedical Imaging (ISBI), 2015 IEEE 12th International Symposium on, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 9-12Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Recently, numerous micro-channels have been discovered in the human temporal bone by micro-CT-scanning. Preliminary structure of these channels has suggested they contain a new separate blood supply for the mucosa of the mastoid air cells, which may have important functional implications. This paper proposes a structural analysis of the microchannels to corroborate this role. A local structure tensor is first estimated. The eigenvalues obtained from the estimated local structure tensor were then used to build probability maps representing planar, tubular, and isotropic tensor types. Each tensor type was assigned a respective RGB color and the full structure tensor was rendered along with the original data. Such structural analysis provides new and relevant information about the micro-channels but also their connections to mastoid air cells. Before carrying a future statistical analysis, a more accurate representation of the micro-channels in terms of local structure tensor analysis using adaptive filtering is needed.

    sted, utgiver, år, opplag, sider
    Institute of Electrical and Electronics Engineers (IEEE), 2015
    Serie
    IEEE International Symposium on Biomedical Imaging, ISSN 1945-7928
    Emneord
    Human temporal bone, mastoid, microchannels, quadrature filters, structure tensor, visualization
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-122177 (URN)10.1109/ISBI.2015.7163804 (DOI)000380546000003 ()978-1-4799-2374-8 (ISBN)
    Konferanse
    IEEE 12th International Symposium on Biomedical Imaging (ISBI), 2015 IEEE 12th International Symposium on, 16-19 April, New York, USA
    Tilgjengelig fra: 2015-10-23 Laget: 2015-10-23 Sist oppdatert: 2017-05-10bibliografisk kontrollert
    4. Enhancement of micro-channels within the human mastoid bone based on local structure tensor analysis
    Åpne denne publikasjonen i ny fane eller vindu >>Enhancement of micro-channels within the human mastoid bone based on local structure tensor analysis
    2016 (engelsk)Inngår i: Image Proceessing Theory, Tools and Apllications, IEEE, 2016Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Numerous micro-channels have recently been discovered in the human temporal bone by x-ray micro-CT-scanning. After a preliminary study suggesting that these micro-channels form a separate blood supply for the mucosa of the mastoid air cells, a structural analysis of the micro-channels using a local structure tensor was carried out. Despite the high-resolution of the micro-CT scan, presence of noise within the air cells along with missing information in some micro-channels suggested the need of image enhancement. This paper proposes an adaptive enhancement of the micro-channels based on a local structure analysis while minimizing the impact of noise on the overall data. Comparison with an anisotropic diffusion PDE based scheme was also performed.

    sted, utgiver, år, opplag, sider
    IEEE, 2016
    Serie
    International Conference on Image Processing Theory Tools and Applications (IPTA), E-ISSN 2154-512X
    Emneord
    Micro-channels, Structure tensor analysis, Image enhancement, Adaptive filtering, Human temporal bone, Mastoid bone
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-134434 (URN)10.1109/IPTA.2016.7821019 (DOI)000393589800071 ()9781467389105 (ISBN)9781467389112 (ISBN)
    Konferanse
    6th International Conference on Image Processing Theory Tools and Applications (IPTA), Oulu, Finland, 12-15 December 2016
    Merknad

    Funding agencies: Obel Family Foundation (Denmark)

    Tilgjengelig fra: 2017-02-13 Laget: 2017-02-13 Sist oppdatert: 2017-06-21
  • 374.
    Cros, Olivier
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Pauwels, Elin
    University of Ghent, Belgium.
    Dirckx, Joris J. J.
    University of Antwerp, Belgium.
    Gaihede, Michael
    Aalborg University Hospital, Denmark.
    Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning2013Inngår i: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 301, s. 60-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mastoid air cell system has traditionally been considered to have a passive role in gas exchange and pressure regulation of the middle ear possibly with some acoustic function. However, more evidence has focused on the mucosa of the mastoid, which may play a more active role in regulation of middle ear pressure.

    In this study we have applied micro-CT scanning on a series of three human temporal bones. This approach greatly enhances the resolution (40–60 μm), so that we have discovered anatomical details, which has not been reported earlier. Thus, qualitative analysis using volume rendering has demonstrated notable micro-channels connecting the surface of the compact bone directly to the mastoid air cells as well as forming a network of connections between the air cells. Quantitative analysis on 2D slices was employed to determine the average diameter of these micro-channels (158 μm; range = 40–440 μm) as well as their density at a localized area (average = 75 cm−2; range = 64–97 cm−2).

    These channels are hypothesized to contain a separate vascular supply for the mastoid mucosa. However, future studies of the histological structure of the micro-channels are warranted to confirm the hypothesis. Studies on the mastoid mucosa and its blood supply may improve our knowledge of its physiological properties, which may have important implications for our understanding of the pressure regulation of the middle ear.

  • 375.
    Cros, Olivier
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Aalborg Unversity Hospital, Denmark.
    Eklund, Anders
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för datavetenskap, Statistik och maskininlärning. Linköpings universitet, Filosofiska fakulteten.
    Gaihede, Michael
    Department of Otolaryngology, Head & Neck Surgery, Aalborg University Hospital, Denmark.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Enhancement of micro-channels within the human mastoid bone based on local structure tensor analysis2016Inngår i: Image Proceessing Theory, Tools and Apllications, IEEE, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Numerous micro-channels have recently been discovered in the human temporal bone by x-ray micro-CT-scanning. After a preliminary study suggesting that these micro-channels form a separate blood supply for the mucosa of the mastoid air cells, a structural analysis of the micro-channels using a local structure tensor was carried out. Despite the high-resolution of the micro-CT scan, presence of noise within the air cells along with missing information in some micro-channels suggested the need of image enhancement. This paper proposes an adaptive enhancement of the micro-channels based on a local structure analysis while minimizing the impact of noise on the overall data. Comparison with an anisotropic diffusion PDE based scheme was also performed.

  • 376.
    Cros, Olivier
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Department of Otolaryngology, Head and Neck Surgery, Aalborg University Hospital, Denmark.
    Gaihede, Michael
    Department of Otolaryngology, Head and Neck Surgery, Aalborg University Hospital, Denmark / Department of Clinical Medicine, Aalborg University, Denmark.
    Andersson, Mats
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Structural Analysis of Micro-channels in Human Temporal Bone2015Inngår i: IEEE 12th International Symposium on Biomedical Imaging (ISBI), 2015 IEEE 12th International Symposium on, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 9-12Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recently, numerous micro-channels have been discovered in the human temporal bone by micro-CT-scanning. Preliminary structure of these channels has suggested they contain a new separate blood supply for the mucosa of the mastoid air cells, which may have important functional implications. This paper proposes a structural analysis of the microchannels to corroborate this role. A local structure tensor is first estimated. The eigenvalues obtained from the estimated local structure tensor were then used to build probability maps representing planar, tubular, and isotropic tensor types. Each tensor type was assigned a respective RGB color and the full structure tensor was rendered along with the original data. Such structural analysis provides new and relevant information about the micro-channels but also their connections to mastoid air cells. Before carrying a future statistical analysis, a more accurate representation of the micro-channels in terms of local structure tensor analysis using adaptive filtering is needed.

  • 377.
    Cros, Olivier
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Department of Otolaryngology, Head & Neck Surgery, Aalborg University Hospital, Denmark.
    Gaihede, Michael
    Department of Otolaryngology, Head & Neck Surgery, Aalborg University Hospital, Denmark; Department of Clinical Medicine, Aalborg University, Denmark.
    Eklund, Anders
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för datavetenskap, Statistik och maskininlärning. Linköpings universitet, Filosofiska fakulteten.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Surface and curve skeleton from a structure tensor analysis applied on mastoid air cells in human temporal bones2017Inngår i: IEEE 14th International Symposium on Biomedical Imaging (ISBI 2017), 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 270-274Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The mastoid of human temporal bone contains numerous air cells connected to each others. In order to gain further knowledge about these air cells, a more compact representation is needed to obtain an estimate of the size distribution of these cells. Already existing skeletonization methods often fail in producing a faithful skeleton mostly due to noise hampering the binary representation of the data. This paper proposes a different approach by extracting geometrical information embedded in the Euclidean distance transform of a volume via a structure tensor analysis based on quadrature filters, from which a secondary structure tensor allows the extraction of surface skeleton along with a curve skeleton from its eigenvalues. Preliminary results obtained on a X-ray micro-CT scans of a human temporal bone show very promising results.

  • 378.
    Cros, Olivier
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Department of Otolaryngology, Head and Neck Surgery, Aalborg Hospital, Aarhus University Hospital, Denmark.
    Gaihede, Michael L.
    Department of Otolaryngology, Head and Neck Surgery, Aalborg Hospital, Aarhus University Hospital, Denmark.
    Borga, Magnus
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Smedby, Örjan
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Mastoid structural properties determined by imaging analysis of high resolution CT-scanning2010Inngår i: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 263, nr 1-2, s. 242-243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hypothesis: The structure of the mastoid air cells can be described by quantitative imaging analysis of high-resolution CT-scans, which may contribute to understand its function in normal and pathological ears. Background: Negative middle ear pressure is a common factor in middle ear diseases resulting from an imbalance between mastoid gas exchange and Eustachian tube function. While the Eustachian tube function has been the main focus of research, more recent studies indicate that the mastoid may play an active role in pressure regulation. The mastoid structure with numerous air cells reflects a large area to volume ratio (AV-ratio) adapted to efficient gas exchange. Imaging analysis applied to high resolution CT-scanning can describe quantitative measures, which may reveal important information about mastoid function and its role in healthy and diseased ears. Materials and methods: Quantitative analysis was performed on a series of unselected high resolution CT-scans (voxel size: 0.29 _ 0.29 _ 0.625 mm) from 36 ears in 24 patients. Area and volume were determined using Cavalieri’s method, i.e. by summing cross-sectional areas. The AV-ratio was computed for each scan. Results: Mean area was 69 cm2 (range: 23–134cm2), mean volume was 4 cm3 (range: 1.3–10.8 cm3), and mean AV-ratio was 16 cm-1 (range: 11.2–21.0 cm-1). The area correlated linearly to the volume by A = 17.2*V-0.2. Conclusion: The area and volume values corresponded with previous studies, and the additional AV-ratio reflected the functional properties of the mastoid in terms of capability for gas exchange. Due to a series of similarities between structure and function of the lungs and mastoid, it seems likely to propose a tree-structure of dividing mastoid cells. In respiratory research, analysis describing the dimensions of series of bronchi generations has been applied, and based on current results; our aim of future research is to establish similar details of mastoid tree-structure. Funding source: Various private Danish funds.

  • 379.
    Cros, Olivier
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Department of Otolaryngology, Head and Neck Surgery, Aalborg University Hospital, Denmark.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Andersson, Mats
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Pawels, Elin
    Centre for X-ray Tomography, Department of Physics and Astronomy, University of Ghent, Belgium.
    Borga, Magnus
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Gaihede, Michael
    Department of Otolaryngology, Head and Neck Surgery, Aalborg University Hospital, Denmark / Department of Clinical Medicine, Aalborg University, Denmark.
    Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bone: Geometrical parameters dependence on scanning resolutions2016Inngår i: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 340, s. 127-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. Thus, these geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA than the V, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.

    Our aim was to determine the SA, V, and SA/V ratio in MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.

    The mean SA was 194 cm2, the mean V was 9 cm3, and the mean SA/V amounted to 22 cm-1. Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.

    The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a separate role of the MACS compared with the tympanum, and the results are important for a more accurate modeling of the middle ear physiology.

  • 380.
    Cubo, Ruben
    et al.
    Uppsala University, Sweden.
    Medvedev, Alexander
    Uppsala University, Sweden.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Model-Based Optimization of Individualized Deep Brain Stimulation Therapy2016Inngår i: IEEE DESIGN and TEST, ISSN 2168-2356, Vol. 33, nr 4, s. 74-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    n/a

  • 381.
    Cubo, Ruben
    et al.
    Uppsala University, Sweden.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten. Medtron Eindhoven Design Centre, Netherlands.
    Medvedev, Alexander
    Uppsala University, Sweden.
    Electric Field Modeling and Spatial Control in Deep Brain Stimulation2015Inngår i: 2015 54TH IEEE CONFERENCE ON DECISION AND CONTROL (CDC), IEEE , 2015, s. 3846-3851Konferansepaper (Fagfellevurdert)
    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.

  • 382.
    Cubo, Ruben
    et al.
    Uppsala Univ, Sweden.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Medvedev, Alexander
    Uppsala Univ, Sweden.
    Optimization-Based Contact Fault Alleviation in Deep Brain Stimulation Leads2018Inngår i: IEEE transactions on neural systems and rehabilitation engineering, ISSN 1534-4320, E-ISSN 1558-0210, Vol. 26, nr 1, s. 69-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deep brain stimulation (DBS) is a neurosurgical treatment in, e.g., Parkinsons Disease. Electrical stimulation in DBS is delivered to a certain target through electrodes implanted into the brain. Recent developments aiming at better stimulation target coverage and lesser side effects have led to an increase in the number of contacts in a DBS lead as well as higher hardware complexity. This paper proposes an optimization-based approach to alleviation of the fault impact on the resulting therapeutical effect in field steering DBS. Faulty contacts could be an issue given recent trends of increasing number of contacts in DBS leads. Hence, a fault detection/alleviation scheme, such as the one proposed in this paper, is necessary ensure resilience in the chronic stimulation. Two alternatives are considered and compared with the stimulation prior to the fault: one using higher amplitudes on the remaining contacts and another with alleviating contacts in the neighborhood of the faulty one. Satisfactory compensation for a faulty contact can be achieved in both ways. However, to designate alleviating contacts, a model-based optimization procedure is necessary. Results suggest that stimulating with more contacts yields configurations that are more robust to contact faults, though with reduced selectivity.

  • 383.
    Cubo, Ruben
    et al.
    Uppsala University, Sweden.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Medvedev, Alexander
    Uppsala University, Sweden.
    Target coverage and selectivity in field steering brain stimulation2014Inngår i: 2014 36TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), Institute of Electrical and Electronics Engineers (IEEE), 2014, s. 522-525Konferansepaper (Fagfellevurdert)
    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.

  • 384.
    Dadi, Kamalaker Reddy
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Tekniska högskolan.
    Circadian Rhythms in the Brain - A first step2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Circadian Rhythms (CR) are driven by a biological clock called as suprachiasmaticnucleus (SCN), located in a brain region called the hypothalamus. These rhythms are very much necessary in maintaining the sleep and wake cycle at appropriate times in a day. As a starting step towards non-invasive investigation of CR, aim is to study changes in the physiological processes of two Regions of Interest (ROI), the hypothalamus and the visual cortex. This was studied using a functional Magnetic Resonance Imaging (fMRI) technique to investigate for any changes or differences in the Blood Oxygen Level Dependent (BOLD)signals extracted from the ROI during a visual stimulation. We acquired and processed fMRI data to extract BOLD signals from ROI and the extracted signals are again further used to study the correlation with the experimental ON-OFF design paradigm.

    The extracted BOLD signals varied a lot between the two specified brain regions within the same subject and between three types of fMRI data. These variations were found in terms of number of activated voxels and also Signal to Noise ratio(SNR) level present in the signals. The number of activated voxels and SNR werehigh in visual cortex whereas low number of activated voxels and low SNR were found in hypothalamus. The correlation between BOLD responses from primaryvisual cortex were shown as positive with the experimental stimulation whereas BOLD responses extracted from hypothalamus have shown a negative correlation in time with the experimental stimulation.

    As a start up of the project, these BOLD responses can provide references for a future use in research studies, especially to further study about change in phase of the BOLD signal extracted exactly from the SCN. These phase responses can then be used to study physiological processing in subjects affected by sleep disorders.

  • 385.
    Dahlqvist Leinhard, Olof
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet.
    Johansson, Andreas
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Rydell, Joakim
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Kihlberg, Johan
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa. Östergötlands Läns Landsting, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Smedby, Örjan
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Bildmedicinskt centrum, Röntgenkliniken i Linköping.
    Nyström, Fredrik H.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet.
    Lundberg, Peter
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Bildmedicinskt centrum, Röntgenkliniken i Linköping.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Quantification of abdominal fat accumulation during hyperalimentation using MRI2009Inngår i: Proceedings of the ISMRM Annual Meeting (ISMRM'09), 2009, Berkeley, CA, USA: International Society for Magnetic Resonance in Medicine , 2009, s. 206-Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    There is an increasing demand for imaging methods that can be used for automatic, accurate and quantitative determination of the amounts of abdominal fat. Such methods are important as they will allow the evaluation of some of the risk factors underlying the ’metabolic syndrome’. The metabolic syndrome is becoming common in large parts of the world, and it appears that a dominant risk factor for developing this syndrome is abdominal obesity. Subjects that are afflicted with the metabolic syndrome are exposed to a high risk for developing a large range of diseases such as type 2 diabetes, cardiac failure, and stroke. The aim of this work

  • 386.
    Dahlqvist Leinhard, Olof
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Linge, Jennifer
    Advanced MR Analytics AB, Linköping, Sweden.
    West, Janne
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Medicinska fakulteten.
    Bell, Jimmy
    Westminster University, London, UK.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten.
    Body Composition Profiling using MRI - Normative Data for Subjects with Cardiovascular Disease Extracted from the UK Biobank Imaging Cohort2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    PURPOSE

    To describe the distribution of MRI-derived body composition measurements in subjects with cardiovascular disease (CVD) compared to subjects without any history of CVD.

    METHOD AND MATERIALS

    1864 males and 2036 females with an age range from 45 to 78 years from the UK Biobank imaging study were included in the study. Visceral adipose tissue volume normalized with height2 (VATi), total abdominal adipose tissue volume normalized with height2 (ATATi), total lean thigh muscle volume normalized with body weight (muscle ratio) and liver proton density fat fraction (PDFF) were measured with a 2-point Dixon imaging protocol covering neck to knee and a 10-point Dixon single slice protocol positioned within the liver using a 1.5T MR-scanner (Siemens, Germany). The MR-images were analyzed using AMRA® Profiler research (AMRA, Sweden). 213 subjects with history of cardiovascular events (angina, heart attack, or stroke) (event group) were age and gender matched to subjects with high blood pressure (HBP group), and subjects without CVD (controls).Kruskal-Wallis and Mann-Whitney U tests were used to test the observed differences for each measurement and group without correction for multiple comparisons.

    RESULTS

    VATi in the event group was 1.73 (1.13 - 2.32) l/m2 (median, 25%-75% percentile) compared to 1.68 (1.19 - 2.23) in the HBP group, and 1.30 (0.82-1.87) in the controls. ATATi in the event group was 4.31 (2.90-5.39) l/m2 compared to 4.05 (3.07-5.12) in the HBP group, and 3.48 (2.48-4.61) in the controls. Muscle ratio in the event group was 0.13 (0.12 - 0.15) l/kg as well as in the HBP group, compared to 0.14 (0.12 - 0.15) in the controls. Liver PDFF in the event group was 2.88 (1.77 - 7.72) % compared to 3.44 (2.04-6.18) in the HBP group, and 2.50 (1.58 - 5.15) in the controls. Kruskal-Wallis test showed significant differences for all variables and group comparisons (p<0.007). The post hoc test showed significant differences comparing the controls to both the event group and the HBP group. These were more significant for VATi and ATATi (p<10-4) than for muscle ratio and PDFF (p<0.03). No significant differences were detected between the event group and the HBP group.

    CONCLUSION

    Cardiovascular disease is strongly associated with high VATi, liver fat, and ATATi, and with low muscle ratio.

    CLINICAL RELEVANCE/APPLICATION

    The metabolic syndrome component in CVD can be effectively described using MRI-based body composition profiling.

  • 387.
    Dahlqvist Leinhard, Olof
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Linge, Jennifer
    Advanced MR Analytics AB, Linköping, Sweden.
    West, Janne
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Medicinska fakulteten.
    Bell, Jimmy
    Westminster University, London, UK.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Body Composition Profiling using MRI - Normative Data for Subjects with Diabetes Extracted from the UK Biobank Imaging Cohort2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    PURPOSE

    To describe the distribution of MRI derived body composition measurements in subjects with diabetes mellitus (DM) compared to subjects without diabetes.

    METHOD AND MATERIALS

    3900 subjects (1864 males and 2036 females) from the UK Biobank imaging study were included in the study. The age range was 45 to 78 years. Visceral adipose tissue volume normalized with height2 (VATi), total abdominal adipose tissue volume normalized with height2 (ATATi), total lean thigh muscle volume normalized with body weight (muscle ratio) and liver proton density fat fraction (PDFF) were measured with a 6 minutes 2-point Dixon imaging protocol covering neck to knee and a 10-point Dixon single axial slice protocol positioned within the liver using a 1.5T MR-scanner (Siemens, Germany). The MR-images were analyzed using AMRA® Profiler research (AMRA, Sweden). 194 subjects with clinically diagnosed DM (DM group) were age and gender matched to subjects without DM (control group). For each variable and group, the median, 25%-percentile and 75%-percentile was calculated. Mann-Whitney U test was used to test the observed differences.

    RESULTS

    VATi in the DM group was 2.13 (1.43-2.62) l/m2 (median, 25% - 75% percentile) compared to 1.32 (0.86 - 1.79) l/m2 in the control group. ATATi in the DM group was 4.94 (3.86-6.19) l/m2 compared to 3.40 (2.56 - 4.70) l/m2 in the control group. Muscle ratio in the DM group was 0.13 (0.11 - 0.14) l/kg compared to 0.14 (0.12 - 0.15) l/kg in the control group. Liver PDFF in the DM group was 7.23 (2.68 - 13.26) % compared to 2.49 (1.53 - 4.73) % in the control group. Mann-Whitney U test detected significant differences between the DM group and the control group for all variables (p<10-5).

    CONCLUSION

    DM is strongly associated with high visceral fat, liver fat, and total abdominal fat, and low muscle ratio.

    CLINICAL RELEVANCE/APPLICATION

    Body composition profiling shows high potential to provide direct biomarkers to improve characterization and early diagnosis of DM.

  • 388.
    Dahlqvist Leinhard, Olof
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Romu, Thobias
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Karlsson, Anette
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    High resolution isotropic whole-­‐body symmetrically sampled two point Dixon acquisition imaging at 3T2012Inngår i: ISMRM workshop on Fat-­‐Water Separation: Insights, Applications & Progress in MRI, 2012Konferansepaper (Annet vitenskapelig)
  • 389.
    Dahlqvist Leinhard, Olof
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Romu, Thobias
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Kihlberg, Johan
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet.
    Gjellan, Solveig
    Linköpings universitet, Institutionen för medicin och hälsa, Internmedicin. Linköpings universitet, Hälsouniversitetet.
    Zanjani, Sepehr
    Linköpings universitet, Institutionen för medicin och hälsa, Internmedicin. Linköpings universitet, Hälsouniversitetet.
    Smedby, Örjan
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Nyström, Fredrik
    Linköpings universitet, Institutionen för medicin och hälsa, Internmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Endokrinmedicinska enheten.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Validation of whole-­‐body adipose tissue quantification using air displacement plethysmometry2012Inngår i: ISMRM workshop on Fat-­‐Water Separation: Insights, Applications & Progress in MRI, 2012Konferansepaper (Annet vitenskapelig)
  • 390.
    Dahlström, Örjan
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Babic, Ankica
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Antonsson, Johan
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Lönn, Urban
    Uppsala Universitet.
    Ahn, Henrik Casimir
    Linköpings universitet, Institutionen för medicin och vård, Thoraxkirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.
    Clustering as a data mining method in a Web-based system for thoracic surgery2001Inngår i: Journal of the Medical Informatics Association. Symposium Supplement, Washington: Hanley&Belfus , 2001, s. 888-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cluster analysis is one way of data mining from large amounts of information. Being able to perform series of analyses, varying clinical criteria and requests, expected results of the clustering might be truly rewarding. Instead of having a few hypotheses prepared and tested, medical experts can be surprised by obtaining a set of hypotheses to further validate and work on.

    Internet technologies enable a substantial flexibility that can be taken advantage of when implementing a Web-based tool. Division of Medical Informatics together with Linkoping Heart Center of the Linkoping University is developing procedures for multivariate clustering within the Web-based AssistMe1 system.

  • 391.
    Danbolt, Christina
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för neurovetenskap. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Diagnostikcentrum, Klinisk patologi och klinisk genetik.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Filosofiska fakulteten.
    Grahn, Lita Tibbling
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Validation and characterization of the computerized laryngeal analyzer (CLA) technique.1999Inngår i: Dysphagia (New York. Print), ISSN 0179-051X, E-ISSN 1432-0460, Vol. 14, nr 4, s. 191-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate the response characteristics of the Computerized Laryngeal Analyzer (CLA) and the validity of the noninvasive CLA method to detect swallowing-induced laryngeal elevation correctly. Two healthy adults and two experimental models were used in the study. The CLA technique identified all swallowing events but was unable to discriminate between swallowing and other movements of the tongue or the neck. The computer program produced a derivated response to a square wave signal. Stepwise bending increments of the sensor displayed a linear amplitude response. The degree of laryngeal elevation could not be estimated with the CLA technique, and it was not possible to draw any reliable conclusions from the recordings as to whether the larynx was moving upward or downward.

  • 392.
    Danbolt, Christina
    et al.
    Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Oto-Rhino-Laryngologi. Linköpings universitet, Hälsouniversitetet.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Tibbling Grahn, Lita
    Linköpings universitet, Institutionen för nervsystem och rörelseorgan, Oto-Rhino-Laryngologi. Linköpings universitet, Hälsouniversitetet.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Validation and characterization of the computerized laryngeal analyzer (CLA) technique1999Inngår i: Dysphagia (New York. Print), ISSN 0179-051X, E-ISSN 1432-0460, Vol. 14, nr 4, s. 191-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate the response characteristics of the Computerized Laryngeal Analyzer (CLA) and the validity of the noninvasive CLA method to detect swallowing-induced laryngeal elevation correctly. Two healthy adults and two experimental models were used in the study. The CLA technique identified all swallowing events but was unable to discriminate between swallowing and other movements of the tongue or the neck. The computer program produced a derivated response to a square wave signal. Stepwise bending increments of the sensor displayed a linear amplitude response. The degree of laryngeal elevation could not be estimated with the CLA technique, and it was not possible to draw any reliable conclusions from the recordings as to whether the larynx was moving upward or downward.

  • 393.
    Danielis, Alessandro
    et al.
    CNR, Italy.
    Giorgi, Daniela
    CNR, Italy.
    Larsson, Marcus
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Strömberg, Tomas
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Colantonio, Sara
    CNR, Italy.
    Salvetti, Ovidio
    CNR, Italy.
    Lip segmentation based on Lambertian shadings and morphological operators for hyper-spectral images2017Inngår i: Pattern Recognition, ISSN 0031-3203, E-ISSN 1873-5142, Vol. 63, s. 355-370Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 394.
    De Biase, Alessia
    et al.
    Division of Statistics and Machine learning, Department of Computer and Information Science, Linkoping University, Linkoping, Sweden, ContextVision AB, Stockholm, Sweden .
    Burlutskiy, Nikolay
    ContextVision AB, Stockholm, Sweden .
    Pinchaud, Nicolas
    ContextVision AB, Stockholm, Sweden.
    Eklund, Anders
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Institutionen för datavetenskap, Statistik och maskininlärning. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Deep Learning Data Augmentation Approach to Improve Cancer Segmentation Performance across Different Scanners2019Konferansepaper (Fagfellevurdert)
  • 395.
    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
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten. 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 tremor2017Inngår i: NeuroImage: Clinical, ISSN 0353-8842, E-ISSN 2213-1582, Vol. 13Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 396.
    Deniz, Daniel
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Causes of multimodality of efficiency gain distributions in accelerated Monte Carlo based dose calculations for brachytherapy planning using correlated sampling2009Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Fixed-collision correlated sampling for Monte Carlo (MC) simulations is a method which can be used in order to shorten the simulation time for brachytherapy treatment planning in a 3D patient geometry. The increased efficiency compared to conventional MC simulation is measured by efficiency gain. However, a previous study showed that, in some cases, PDFs (probability density functions) of estimates of the efficiency gain, simulated using resampling and other MC methods, were multimodal with values below 1. This means that the method was less effective than conventional sampling for these cases. The aims of this thesis were to trace the causes of the multimodal distributions and to propose techniques to mitigate the problem caused by photons with high statistical weights.Two simulation environments were used for the study case, a homogeneous and a heterogeneous environment. The homogenous environment consisted of a water sphere with the radius 100mm. For the heterogeneous environment a cylindrical block of tungsten alloy (diameter 15 mm, height 2.5 mm) was placed in the water sphere. The sphere was divided into an array of cubic voxels of size 2.5 mm x 2.5 mm x 2.5 mm for dose calculations. A photon source was positioned in the middle of the water sphere and emitted photons with the energy 400 keV.It was found that the low values and multimodal PDFs for the efficiency gain estimates originated from photons depositing high values of energy in some voxels in the heterogeneous environment. The high energy deposits were due to extremely high statistical weights of photons interacting repeatedly in the highly attenuating tungsten cylinder. When photon histories contributing to the rare events of high energy deposits (outliers) were removed, the PDFs became uni-modal and efficiency gain increased. However, removing outliers will cause results to be biased calling for other techniques to handle the problem with high statistical weights.One way to resolve the problem in the current implementation of the fixed-collision correlated sampling scheme in PTRAN (the MC code used) could be to split photons with high statistical weights into several photons with the same sum weight as the initial photon. The splitting of photons will result in more time consuming simulations in areas with high attenuation coefficients, which may not be the areas of interest. This could be resolved by using Russian roulette, eliminating some of the photons with high statistical weight in such areas.Fixed-collision correlated sampling for Monte Carlo (MC) simulations is a method which can be used in order to shorten the simulation time for brachytherapy treatment planning in a 3D patient geometry. The increased efficiency compared to conventional MC simulation is measured by efficiency gain. However, a previous study showed that, in some cases, PDFs (probability density functions) of estimates of the efficiency gain, simulated using resampling and other MC methods, were multimodal with values below 1. This means that the method was less effective than conventional sampling for these cases. The aims of this thesis were to trace the causes of the multimodal distributions and to propose techniques to mitigate the problem caused by photons with high statistical weights.Two simulation environments were used for the study case, a homogeneous and a heterogeneous environment. The homogenous environment consisted of a water sphere with the radius 100mm. For the heterogeneous environment a cylindrical block of tungsten alloy (diameter 15 mm, height 2.5 mm) was placed in the water sphere. The sphere was divided into an array of cubic voxels of size 2.5 mm x 2.5 mm x 2.5 mm for dose calculations. A photon source was positioned in the middle of the water sphere and emitted photons with the energy 400 keV.It was found that the low values and multimodal PDFs for the efficiency gain estimates originated from photons depositing high values of energy in some voxels in the heterogeneous environment. The high energy deposits were due to extremely high statistical weights of photons interacting repeatedly in the highly attenuating tungsten cylinder. When photon histories contributing to the rare events of high energy deposits (outliers) were removed, the PDFs became uni-modal and efficiency gain increased. However, removing outliers will cause results to be biased calling for other techniques to handle the problem with high statistical weights.One way to resolve the problem in the current implementation of the fixed-collision correlated sampling scheme in PTRAN (the MC code used) could be to split photons with high statistical weights into several photons with the same sum weight as the initial photon. The splitting of photons will result in more time consuming simulations in areas with high attenuation coefficients, which may not be the areas of interest. This could be resolved by using Russian roulette, eliminating some of the photons with high statistical weight in such areas.

  • 397.
    Dentler, Kathrin
    et al.
    Vrije University of Amsterdam, Netherlands; University of Amsterdam, Netherlands.
    Cornet, Ronald
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. University of Amsterdam, Netherlands.
    Intra-axiom redundancies in SNOMED CT2015Inngår i: Artificial Intelligence in Medicine, ISSN 0933-3657, E-ISSN 1873-2860, Vol. 65, nr 1, s. 29-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: Intra-axiom redundancies are elements of concept definitions that are redundant as they are entailed by other elements of the concept definition. While such redundancies are harmless from a logical point of view, they make concept definitions hard to maintain, and they might lead to content-related problems when concepts evolve. The objective of this study is to develop a fully automated method to detect intra-axiom redundancies in OWL 2 EL and apply it to SNOMED Clinical Terms (SNOMED CT). Materials and methods: We developed a software program in which we implemented, adapted and extended readily existing rules for redundancy elimination. With this, we analysed occurence of redundancy in 11 releases of SNOMED CT(January 2009 to January 2014). We used the ELK reasoner to classify SNOMED CT, and Pellet for explanation of equivalence. We analysed the completeness and soundness of the results by an in-depth examination of the identified redundant elements in the July 2012 release of SNOMED CT. To determine if concepts with redundant elements lead to maintenance issues, we analysed a small sample of solved redundancies. Results: Analyses showed that the amount of redundantly defined concepts in SNOMED CT is consistently around 35,000. In the July 2012 version of SNOMED CT, 35,010(12%) of the 296,433 concepts contained redundant elements in their definitions. The results of applying our method are sound and complete with respect to our evaluation. Analysis of solved redundancies suggests that redundancies in concept definitions lead to inadequate maintenance of SNOMED CT. Conclusions: Our analysis revealed that redundant elements are continuously introduced and removed, and that redundant elements may be overlooked when concept definitions are corrected. Applying our redundancy detection method to remove intra-axiom redundancies from the stated form of SNOMED CT and to point knowledge modellers to newly introduced redundancies can support creating and maintaining a redundancy-free version of SNOMED CT. (C) 2014 Elsevier B.V. All rights reserved.

  • 398.
    Dentler, Kathrin
    et al.
    Vrije University of Amsterdam, Netherlands University of Amsterdam, Netherlands .
    Cornet, Ronald
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan. University of Amsterdam, Netherlands.
    ten Teije, Annette
    Vrije University of Amsterdam, Netherlands .
    Tanis, Pieter
    University of Amsterdam, Netherlands .
    Klinkenbijl, Jean
    University of Amsterdam, Netherlands .
    Tytgat, Kristien
    University of Amsterdam, Netherlands .
    de Keizer, Nicolette
    University of Amsterdam, Netherlands .
    Influence of data quality on computed Dutch hospital quality indicators: a case study in colorectal cancer surgery2014Inngår i: BMC Medical Informatics and Decision Making, ISSN 1472-6947, E-ISSN 1472-6947, Vol. 14, nr 32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Our study aims to assess the influence of data quality on computed Dutch hospital quality indicators, and whether colorectal cancer surgery indicators can be computed reliably based on routinely recorded data from an electronic medical record (EMR). Methods: Cross-sectional study in a department of gastrointestinal oncology in a university hospital, in which a set of 10 indicators is computed (1) based on data abstracted manually for the national quality register Dutch Surgical Colorectal Audit (DSCA) as reference standard and (2) based on routinely collected data from an EMR. All 75 patients for whom data has been submitted to the DSCA for the reporting year 2011 and all 79 patients who underwent a resection of a primary colorectal carcinoma in 2011 according to structured data in the EMR were included. Comparison of results, investigating the causes for any differences based on data quality analysis. Main outcome measures are the computability of quality indicators, absolute percentages of indicator results, data quality in terms of availability in a structured format, completeness and correctness. Results: All indicators were fully computable based on the DSCA dataset, but only three based on EMR data, two of which were percentages. For both percentages, the difference in proportions computed based on the two datasets was significant. All required data items were available in a structured format in the DSCA dataset. Their average completeness was 86%, while the average completeness of these items in the EMR was 50%. Their average correctness was 87%. Conclusions: Our study showed that data quality can significantly influence indicator results, and that our EMR data was not suitable to reliably compute quality indicators. EMRs should be designed in a way so that the data required for audits can be entered directly in a structured and coded format.

  • 399.
    Dentler, Kathrin
    et al.
    Vrije University of Amsterdam, Netherlands University of Amsterdam, Netherlands .
    Numans, Mattijs E.
    University of Medical Centre Utrecht, Netherlands Vrije University of Amsterdam, Netherlands .
    ten Teije, Annette
    Vrije University of Amsterdam, Netherlands .
    Cornet, Ronald
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. University of Amsterdam, Netherlands.
    de Keizer, Nicolette F.
    University of Amsterdam, Netherlands .
    Formalization and computation of quality measures based on electronic medical records2014Inngår i: JAMIA Journal of the American Medical Informatics Association, ISSN 1067-5027, E-ISSN 1527-974X, Vol. 21, nr 2, s. 285-291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective Ambiguous definitions of quality measures in natural language impede their automated computability and also the reproducibility, validity, timeliness, traceability, comparability, and interpretability of computed results. Therefore, quality measures should be formalized before their release. We have previously developed and successfully applied a method for clinical indicator formalization (CLIF). The objective of our present study is to test whether CLIF is generalizablethat is, applicable to a large set of heterogeneous measures of different types and from various domains. Materials and methods We formalized the entire set of 159 Dutch quality measures for general practice, which contains structure, process, and outcome measures and covers seven domains. We relied on a web-based tool to facilitate the application of our method. Subsequently, we computed the measures on the basis of a large database of real patient data. Results Our CLIF method enabled us to fully formalize 100% of the measures. Owing to missing functionality, the accompanying tool could support full formalization of only 86% of the quality measures into Structured Query Language (SQL) queries. The remaining 14% of the measures required manual application of our CLIF method by directly translating the respective criteria into SQL. The results obtained by computing the measures show a strong correlation with results computed independently by two other parties. Conclusions The CLIF method covers all quality measures after having been extended by an additional step. Our web tool requires further refinement for CLIF to be applied completely automatically. We therefore conclude that CLIF is sufficiently generalizable to be able to formalize the entire set of Dutch quality measures for general practice.

  • 400.
    Dentler, Kathrin
    et al.
    Dept. of Computer Science, VU University Amsterdam, The Netherlands and Dept. of Medical Informatics, Academic Medical Center, University of Amsterdam, The Netherlands.
    Ten Teije, Annette
    Dept. of Computer Science, VU University Amsterdam, The Netherlands.
    de Keizer, Nicolette
    Dept. of Medical Informatics, Academic Medical Center, University of Amsterdam, The Netherlands.
    Cornet, Ronald
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Barriers to the reuse of routinely recorded clinical data: a field report2013Inngår i: Proceedings of Studies in Health Technology & Informatics, vol.192, IOS Press, 2013, Vol. 192, s. 313-317Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Today, clinical data is routinely recorded in vast amounts, but its reuse can be challenging. A secondary use that should ideally be based on previously collected clinical data is the computation of clinical quality indicators. In the present study, we attempted to retrieve all data from our hospital that is required to compute a set of quality indicators in the domain of colorectal cancer surgery. We categorised the barriers that we encountered in the scope of this project according to an existing framework, and provide recommendations on how to prevent or surmount these barriers. Assuming that our case is not unique, these recommendations might be applicable for the design, evaluation and optimisation of Electronic Health Records.

567891011 351 - 400 of 2207
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf