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  • 1.
    Antonsson, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    On optical methods for intracerebral measurements during stereotactic and functional neurosurgery: Experimental studies2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Radio frequency (RF) lesioning and deep brain stimulation (DBS) are the two prevailing surgical treatments for movement disorders within the field of stereotactic and functional neurosurgery. For RF-lesioning, a small volume of brain tissue is coagulated and knowledge of the lesion size and growth is of great importance for the safety and outcome of the procedure. This thesis deals with adapting the laser Doppler perfusion monitoring (LDPM) technique for measurements in brain tissue during RF-lesioning. The relation between LDPM signal changes and developed lesion size was investigated. LDPM measurements were evaluated both in vitro (albumin protein solution) and in vivo in the porcine brain during RF-lesioning corresponding to a bilateral thalamotomy in man. The investigated signals from the LDPI measurements can be used for following the lesioning time course and to detect if a lesion was created, both in vitro and in the animal model. For the albumin model, both the total backscattered light intensity and the perfusion signal can be used as markers for estimating the final coagulation size, while in the animal model this conclusion was not statistical verified.

    Independent on surgical method, RF-lesioning or DBS, intracerebral guidance is an important aspect within stereotactic and functional neurosurgery. To increase the accuracy and precision of reaching the correct target, different methods for intracerebral guidance exist, such as microelectrode recording and impedance methods. In this thesis, the possibility of developing an optical intracerebral guidance method has been investigated. Diffuse reflectance spectroscopy served as technology and all measurements were performed stereotactically in both porcine and human brain. Measurements of white and gray matter showed large differences, with higher reflectivity for white brain matter, both in porcine and in human brain. For the human measurements during DBS-implants, large differences between white matter and functional targets were found. Additionally, differences between native and lesioned porcine brain matter were detected. Both studies support the idea of using diffuse reflectance spectroscopy for developing an intracerebral guidance method.

    List of papers
    1. Radio frequency electrode system for optical lesion size estimation in functional neurosurgery
    Open this publication in new window or tab >>Radio frequency electrode system for optical lesion size estimation in functional neurosurgery
    2005 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, no 3, p. 1-6Article in journal (Refereed) Published
    Abstract [en]

    Radiofrequency(RF) lesioning in the human brain is one possible surgicaltherapy for severe pain as well as movement disorders. Oneobstacle for a safer lesioning procedure is the lack ofsize monitoring. The aim of this study was to investigateif changes in laser Doppler or intensity signals could beused as markers for size estimation during experimental RF lesioning.A 2 mm in diameter monopolar RF electrode was equippedwith optical fibers and connected to a digital laser Dopplersystem. The optical RF electrode's performance was equal to astandard RF electrode with the same dimensions. An albumin solutionwith scatterers was used to evaluate the intensity and laserDoppler signal changes during lesioning at 70, 80, and 90 °C.Significant signal changes were found for these three different clotsizes, represented by the temperatures (p<0.05,  n=10). The volume, width, andlength of the created coagulations were correlated to the intensitysignal changes (r=0.88, n=30, p<0.0001) and to the perfusion signalchanges (r=0.81, n=30, p<0.0001). Both static and Doppler-shifted light canbe used to follow the lesioning procedure as well asbeing used for lesion size estimation during experimental RF lesioning.

    Place, publisher, year, edition, pages
    SPIE - International Society for Optical Engineering, 2005
    National Category
    Atom and Molecular Physics and Optics
    Identifiers
    urn:nbn:se:liu:diva-14232 (URN)10.1117/1.1924615 (DOI)000235127400040 ()16229664 (PubMedID)2-s2.0-24144476322 (Scopus ID)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
    2. Optical measurements during experimental stereotactic radiofrequency lesioning
    Open this publication in new window or tab >>Optical measurements during experimental stereotactic radiofrequency lesioning
    2006 (English)In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 84, no 2-3, p. 118-124Article in journal (Refereed) Published
    Abstract [en]

    The aim of this study was to evaluate in vivo a laser Doppler measurement system in porcine brain tissue during thermal lesioning. A 2-mm monopolar radiofrequency lesioning electrode was equipped with optical fibers in order to monitor the lesioning procedure. Laser Doppler and backscattered light intensity signals were measured along the electrode trajectory and during bilateral lesioning in the central gray (70, 80 and 90°C, n = 14). The time course of the coagulation process could be followed by optical recordings. Two separate groups of tissue were identified from the intensity signals. The changes in the perfusion levels in both groups displayed significant changes (p < 0.05, n = 48) at all temperature settings, while backscattered light intensity was significant for only one group at the different temperatures (p < 0.05, n = 39). These results indicate that optical measurements correlate with lesion development in vivo. The study also indicates that it is possible to follow the lesioning process intra-operatively.

    Place, publisher, year, edition, pages
    S. Karger, 2006
    Keywords
    Laser Doppler, Radiofrequency lesioning, Functional neurosurgery, Brain electrodes
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-14233 (URN)10.1159/000094463 (DOI)000239562300010 ()16840822 (PubMedID)2-s2.0-33746647435 (Scopus ID)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
    3. In-vivo reflection spectroscopy measurements in pig brain during stereotactic surgery
    Open this publication in new window or tab >>In-vivo reflection spectroscopy measurements in pig brain during stereotactic surgery
    2003 (English)In: Biophotonics West: Biomedical Optics, 2003, Vol. 4958, p. 242-250Conference paper, Published paper (Refereed)
    Abstract [en]

    Radiofrequency (RF) lesioning in the human brain is a commonsurgical therapy for relieving severe pain as well as formovement disorders such as Parkinsonia. During the procedure a smallelectrode is introduced by stereotactic means towards a target arealocalized by CT or MRI. An RF-current is applied throughthe electrode tip when positioned in the target area. Thetissue in the proximity of the tip is heated bythe current and finally coagulated.The overall aim of this studywas to improve the RF-technique and its ability to estimatelesion size by means of optical methods. Therefore, the opticaldifferences between white and gray matter, as well as lesionedand unlesioned tissue were investigated. Reflection spectroscopy measurements in therange of 450-800 nm were conducted on fully anesthetized pigsduring stereotactic RF-lesioning (n=6). Light from a tungsten lamp wasguided to the electrode tip through optical fibers, inserted alonga 2 mm in diameter monopolar RF-electrode. Measurements were performedin steps of 0-10 mm from the target in eachhemisphere towards the entry point of the skull. In thecentral gray of the porcine brain measurements were performed bothbefore and after the creation of a lesion. A totalof 55 spectra were collected during this study. Correlation totissue type was done using post-operative MR-images. The spectral signaturefor white and gray matter differs significantly for the entirespectral range of 450-800 nm. Pre- and post-lesioning reflection spectroscopyshowed the largest differences below 600 and above 620 nm,which implies that lasers within this wavelength range may beuseful for in-vivo measurements of tissue optical changes during RF-lesioning.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14234 (URN)10.1117/12.476131 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-02-22Bibliographically approved
    4. Diffuse reflectance spectroscopy measurements for tissue type discrimination during deep brain stimulation
    Open this publication in new window or tab >>Diffuse reflectance spectroscopy measurements for tissue type discrimination during deep brain stimulation
    Show others...
    2008 (English)In: Journal of neural engineering, ISSN 1741-2560, Vol. 5, no 2, p. 185-190Article in journal (Refereed) Published
    Abstract [en]

    Diffuse reflectance spectroscopy as a method for improving intracerebral guidance during functional neurosurgery has been investigated. An optical probe was developed for measurements during stereotactic and functional neurosurgery in man. The aim of the study was to investigate the spectral differences between white and grey matter and between white matter and functional targets. Diffuse reflectance spectroscopy measurements in ten patients were recorded at incremental steps towards and in three different functional targets (STN, GPi and Zi). The recorded spectra along the trajectory were sorted into white or grey matter, based on preoperative MRI images or the recorded spectral shape and intensity. The difference between tissue types was calculated as a quotient. Significant intensity differences between white and grey matter were found to be at least 14% (p < 0.05) and 20% (p < 0.0001) for MRI and spectral-sorted data respectively. The reflectance difference between white matter and the functional targets of GPi was higher than for STN and Zi. The results indicate that diffuse reflectance spectroscopy has a potential to be developed to a suitable complement to other intracerebral guidance methods.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14235 (URN)10.1088/1741-2560/5/2/009 (DOI)000257253800009 ()18460743 (PubMedID)2-s2.0-48949118315 (Scopus ID)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-02-10Bibliographically approved
    5. In vitro measurements of optical properties of porcine brain using a novel compact device
    Open this publication in new window or tab >>In vitro measurements of optical properties of porcine brain using a novel compact device
    Show others...
    2005 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, no 5, p. 658-666Article in journal (Refereed) Published
    Abstract [en]

    Knowledge of the optical properties of tissues can be applied in numerous medical and scientific fields, including cancer diagnostics and therapy. There are many different ways of determining the optical properties of turbid media. The paper describes measurements of the optical properties of porcine brain tissue using novel instrumentation for simultaneous absorption and scattering characterisation of small turbid samples. Integrating sphere measurements are widely used as a reference method for determination of the optical properties of relatively thin turbid samples. However, this technique is associated with bulky equipment, complicated measuring techniques, interference compensation techniques and inconvenient sample handling. It is believed that the sphere for some applications can be replaced by a new, compact device, called the combined angular and spatially resolved head sensor, to measure the optical properties of thin turbid samples. The results compare very well with data obtained with an integrating sphere for well-defined samples. The instrument was shown to be accurate to within 12% for μa and 1% for μ s in measurements of intralipid-ink samples. The corresponding variations of data were 17% and 2%, respectively. The reduced scattering coefficient for porcine white matter was measured to be 100 cm−1 at 633 nm, and the value for coagulated brain tissue was 65 cm−1. The corresponding absorption coefficients were 2 and 3 cm−1, respectively.

    Place, publisher, year, edition, pages
    Springer, 2005
    Keywords
    Optical properties, Turbid media, Integrating sphere, CASH sensor, Porcine brain tissue, Scattering
    National Category
    Other Medical Engineering
    Identifiers
    urn:nbn:se:liu:diva-14236 (URN)10.1007/BF02351040 (DOI)000234262300016 ()2-s2.0-29244462497 (Scopus ID)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
  • 2.
    Antonsson, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Optical measurements in brain tissue during radio frequency lesioning2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Radio frequency (RF) lesioning is a well well-known procedure within the field of stereotactic neurosurgery, commonly used for the treatment of movement disorders. During the intervention, an RF-electrode is inserted into the deeper parts of the brain, where a small volume of malfunctioning brain tissue will be coagulated. This procedure is irreversible, as a result, the size and position of the created lesion is crucial in order to avoid unwanted side effects. In this thesis a further development of the RF-technology is presented in order to follow a lesioning process and to estimate the created lesion size. Software, electronics, fiber optics and an RF-electrode equipped with optical fibers was developed and evaluated.

    Diffuse reflectance spectroscopy measurements at 450-800 nm in the central gray of porcine brain have been performed with the developed RF-electrode. Measurements of white and gray brain matter showed a large reflectance difference in the investigated wavelength interval, with higher reflectivity for white brain matter. Reflectance differences between native and coagulated, white and gray brain matter were also found .

    In-vitro laser Doppler perfusion monitoring measurements at 633 nm have also been performed in a newly designed flow model. An albumin solution with added glass microspheres was placed on top of a revolving disc. The motion of the liquid surrounding the electrode tip simulated a perfusion situation. Changes in both laser Doppler perfusion and total backscattered light intensity signals were collected during the creation of different sized coagulations. The volume, width and length of the created coagulations are correlated to the measured signal changes in-vitro, where larger coagulations displayed larger signal changes. The laser Doppler perfusion and backscattered light intensity signals can be used to follow the lesioning time course and estimate the developed lesion size in-vitro.

    List of papers
    1. In-vivo reflection spectroscopy measurements in pig brain during stereotactic surgery
    Open this publication in new window or tab >>In-vivo reflection spectroscopy measurements in pig brain during stereotactic surgery
    2003 (English)In: Biophotonics West: Biomedical Optics, 2003, Vol. 4958, p. 242-250Conference paper, Published paper (Refereed)
    Abstract [en]

    Radiofrequency (RF) lesioning in the human brain is a commonsurgical therapy for relieving severe pain as well as formovement disorders such as Parkinsonia. During the procedure a smallelectrode is introduced by stereotactic means towards a target arealocalized by CT or MRI. An RF-current is applied throughthe electrode tip when positioned in the target area. Thetissue in the proximity of the tip is heated bythe current and finally coagulated.The overall aim of this studywas to improve the RF-technique and its ability to estimatelesion size by means of optical methods. Therefore, the opticaldifferences between white and gray matter, as well as lesionedand unlesioned tissue were investigated. Reflection spectroscopy measurements in therange of 450-800 nm were conducted on fully anesthetized pigsduring stereotactic RF-lesioning (n=6). Light from a tungsten lamp wasguided to the electrode tip through optical fibers, inserted alonga 2 mm in diameter monopolar RF-electrode. Measurements were performedin steps of 0-10 mm from the target in eachhemisphere towards the entry point of the skull. In thecentral gray of the porcine brain measurements were performed bothbefore and after the creation of a lesion. A totalof 55 spectra were collected during this study. Correlation totissue type was done using post-operative MR-images. The spectral signaturefor white and gray matter differs significantly for the entirespectral range of 450-800 nm. Pre- and post-lesioning reflection spectroscopyshowed the largest differences below 600 and above 620 nm,which implies that lasers within this wavelength range may beuseful for in-vivo measurements of tissue optical changes during RF-lesioning.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14234 (URN)10.1117/12.476131 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-02-22Bibliographically approved
    2. Radio frequency electrode system for optical lesion size estimation in functional neurosurgery
    Open this publication in new window or tab >>Radio frequency electrode system for optical lesion size estimation in functional neurosurgery
    2005 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, no 3, p. 1-6Article in journal (Refereed) Published
    Abstract [en]

    Radiofrequency(RF) lesioning in the human brain is one possible surgicaltherapy for severe pain as well as movement disorders. Oneobstacle for a safer lesioning procedure is the lack ofsize monitoring. The aim of this study was to investigateif changes in laser Doppler or intensity signals could beused as markers for size estimation during experimental RF lesioning.A 2 mm in diameter monopolar RF electrode was equippedwith optical fibers and connected to a digital laser Dopplersystem. The optical RF electrode's performance was equal to astandard RF electrode with the same dimensions. An albumin solutionwith scatterers was used to evaluate the intensity and laserDoppler signal changes during lesioning at 70, 80, and 90 °C.Significant signal changes were found for these three different clotsizes, represented by the temperatures (p<0.05,  n=10). The volume, width, andlength of the created coagulations were correlated to the intensitysignal changes (r=0.88, n=30, p<0.0001) and to the perfusion signalchanges (r=0.81, n=30, p<0.0001). Both static and Doppler-shifted light canbe used to follow the lesioning procedure as well asbeing used for lesion size estimation during experimental RF lesioning.

    Place, publisher, year, edition, pages
    SPIE - International Society for Optical Engineering, 2005
    National Category
    Atom and Molecular Physics and Optics
    Identifiers
    urn:nbn:se:liu:diva-14232 (URN)10.1117/1.1924615 (DOI)000235127400040 ()16229664 (PubMedID)2-s2.0-24144476322 (Scopus ID)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
  • 3.
    Antonsson, Johan
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Babic, Ankica
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Quality of life using profile in coronary artery bypass surgery patients1999In: AMIA99,1999, Philadelphia: Hanley & Belfus Inc , 1999, p. 1013-Conference paper (Refereed)
  • 4.
    Antonsson, Johan
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Blomstedt, Patric
    Department of Neurosurgery, University Hospital, Umeå, Sweden.
    Bergenheim, Tommy
    Department of Neurosurgery, University Hospital, Umeå, Sweden.
    Hariz, Marwan
    Department of Neurosurgery, University Hospital, Umeå, Sweden.
    Richter, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Diffuse reflectance spectroscopy measurements for tissue type discrimination during deep brain stimulation2008In: Journal of neural engineering, ISSN 1741-2560, Vol. 5, no 2, p. 185-190Article in journal (Refereed)
    Abstract [en]

    Diffuse reflectance spectroscopy as a method for improving intracerebral guidance during functional neurosurgery has been investigated. An optical probe was developed for measurements during stereotactic and functional neurosurgery in man. The aim of the study was to investigate the spectral differences between white and grey matter and between white matter and functional targets. Diffuse reflectance spectroscopy measurements in ten patients were recorded at incremental steps towards and in three different functional targets (STN, GPi and Zi). The recorded spectra along the trajectory were sorted into white or grey matter, based on preoperative MRI images or the recorded spectral shape and intensity. The difference between tissue types was calculated as a quotient. Significant intensity differences between white and grey matter were found to be at least 14% (p < 0.05) and 20% (p < 0.0001) for MRI and spectral-sorted data respectively. The reflectance difference between white matter and the functional targets of GPi was higher than for STN and Zi. The results indicate that diffuse reflectance spectroscopy has a potential to be developed to a suitable complement to other intracerebral guidance methods.

  • 5.
    Antonsson, Johan
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Optical measurements during experimental stereotactic radiofrequency lesioning2006In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 84, no 2-3, p. 118-124Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate in vivo a laser Doppler measurement system in porcine brain tissue during thermal lesioning. A 2-mm monopolar radiofrequency lesioning electrode was equipped with optical fibers in order to monitor the lesioning procedure. Laser Doppler and backscattered light intensity signals were measured along the electrode trajectory and during bilateral lesioning in the central gray (70, 80 and 90°C, n = 14). The time course of the coagulation process could be followed by optical recordings. Two separate groups of tissue were identified from the intensity signals. The changes in the perfusion levels in both groups displayed significant changes (p < 0.05, n = 48) at all temperature settings, while backscattered light intensity was significant for only one group at the different temperatures (p < 0.05, n = 39). These results indicate that optical measurements correlate with lesion development in vivo. The study also indicates that it is possible to follow the lesioning process intra-operatively.

  • 6.
    Antonsson, Johan
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    In-vivo reflection spectroscopy measurements in pig brain during stereotactic surgery2003In: Biophotonics West: Biomedical Optics, 2003, Vol. 4958, p. 242-250Conference paper (Refereed)
    Abstract [en]

    Radiofrequency (RF) lesioning in the human brain is a commonsurgical therapy for relieving severe pain as well as formovement disorders such as Parkinsonia. During the procedure a smallelectrode is introduced by stereotactic means towards a target arealocalized by CT or MRI. An RF-current is applied throughthe electrode tip when positioned in the target area. Thetissue in the proximity of the tip is heated bythe current and finally coagulated.The overall aim of this studywas to improve the RF-technique and its ability to estimatelesion size by means of optical methods. Therefore, the opticaldifferences between white and gray matter, as well as lesionedand unlesioned tissue were investigated. Reflection spectroscopy measurements in therange of 450-800 nm were conducted on fully anesthetized pigsduring stereotactic RF-lesioning (n=6). Light from a tungsten lamp wasguided to the electrode tip through optical fibers, inserted alonga 2 mm in diameter monopolar RF-electrode. Measurements were performedin steps of 0-10 mm from the target in eachhemisphere towards the entry point of the skull. In thecentral gray of the porcine brain measurements were performed bothbefore and after the creation of a lesion. A totalof 55 spectra were collected during this study. Correlation totissue type was done using post-operative MR-images. The spectral signaturefor white and gray matter differs significantly for the entirespectral range of 450-800 nm. Pre- and post-lesioning reflection spectroscopyshowed the largest differences below 600 and above 620 nm,which implies that lasers within this wavelength range may beuseful for in-vivo measurements of tissue optical changes during RF-lesioning.

  • 7.
    Antonsson, Johan
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Radio frequency electrode system for optical lesion size estimation in functional neurosurgery2005In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, no 3, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Radiofrequency(RF) lesioning in the human brain is one possible surgicaltherapy for severe pain as well as movement disorders. Oneobstacle for a safer lesioning procedure is the lack ofsize monitoring. The aim of this study was to investigateif changes in laser Doppler or intensity signals could beused as markers for size estimation during experimental RF lesioning.A 2 mm in diameter monopolar RF electrode was equippedwith optical fibers and connected to a digital laser Dopplersystem. The optical RF electrode's performance was equal to astandard RF electrode with the same dimensions. An albumin solutionwith scatterers was used to evaluate the intensity and laserDoppler signal changes during lesioning at 70, 80, and 90 °C.Significant signal changes were found for these three different clotsizes, represented by the temperatures (p<0.05,  n=10). The volume, width, andlength of the created coagulations were correlated to the intensitysignal changes (r=0.88, n=30, p<0.0001) and to the perfusion signalchanges (r=0.81, n=30, p<0.0001). Both static and Doppler-shifted light canbe used to follow the lesioning procedure as well asbeing used for lesion size estimation during experimental RF lesioning.

  • 8.
    Antonsson, Johan
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Granfeldt, Hans
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Kircher, Albert
    Technical University Graz Austria.
    Babic, Ankica
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Lönn, Urban
    Uppsala .
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Design of a clinical decision support system for assist support devices in thoracic surgery2000In: AMIA,2000, Philadelphia: Hanley & Belfus Inc, , 2000Conference paper (Refereed)
  • 9.
    Dahlström, Örjan
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Babic, Ankica
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Antonsson, Johan
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Lönn, Urban
    Uppsala Universitet.
    Ahn, Henrik Casimir
    Linköping University, Department of Medicine and Care, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Clustering as a data mining method in a Web-based system for thoracic surgery2001In: Journal of the Medical Informatics Association. Symposium Supplement, Washington: Hanley&Belfus , 2001, p. 888-Conference paper (Refereed)
    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.

  • 10.
    Kircher, Albert
    et al.
    Technical University Graz Austria.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Babic, Ankica
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Quantitative data analysis for exploring outcomes in cardiac surgery1999In: Medical Informatics Europe99,1999, Amsterdam: IOS Press , 1999, p. 457-Conference paper (Refereed)
  • 11.
    Kircher, Albert
    et al.
    Technical University Graz Austria.
    Granfeldt, Hans
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Babic, Ankica
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Lönn, Urban
    Hjärtcentrum, Universitetssjukhuset Linköping.
    Ahn, Henrik Casimir
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Knowledge representation forms for data mining methodologies as applied in thoracic surgery2000In: AMIA,2000, Philadelphia: Hanley & Belfus Inc , 2000, p. 428-432Conference paper (Refereed)
    Abstract [en]

    Typical ways of disseminating and using results of clinical research are scientific journals and reports. Presentation forms are condensed and comprehensible mainly to the experts following the specific topics. A vast amount of information remains unutilized due to the complex form of presenting the knowledge. Subject of this research is to explore possibilities of representation and also visualization of the results obtained using data mining methodologies. The intention is to formulate more than scientific ways to communicate facts that are of interest for the clinicians, medical students and even patients. Internet technologies as already widely established media support knowledge representation forms such as hypertext documents and structured knowledge components. The "Assist Me" decision support system for surgical treatment of cardiac patients integrates several forms of data mining and representation methodologies. We are showing a feasibility study in which scientific outcomes were forwarded to a broad group of potential users.

  • 12.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Optical markers for guidance during stereotactic neurosurgery2004In: European Society for Stereotactic and Functional Neurosurgery ESSFN,2004, Wien: Springer Verlag , 2004, p. 881-881Conference paper (Other academic)
  • 13.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Optical measurements during experimental stereotactic neurosurgery2004In: Medicon and Health Telematics,2004, Naples, Italy: AIIMB IFMBE , 2004Conference paper (Refereed)
  • 14.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Blomstedt, P.
    Department of Neurosurgery, University Hospital, Umeå, Sweden.
    Richter, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Zsigmond, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Bergenheim, A.T.
    Department of Neurosurgery, University Hospital, Umeå, Sweden.
    Hariz, M.I.
    Department of Neurosurgery, University Hospital, Umeå, Sweden, Institute of Neurology, University College London, London, United Kingdom.
    Intracerebral microvascular measurements during deep brain stimulation implantation using laser doppler perfusion monitoring2007In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 85, no 6, p. 279-286Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to investigate if laser Doppler perfusion monitoring (LDPM) can be used in order to differentiate between gray and white matter and to what extent microvascular perfusion can be recorded in the deep brain structures during stereotactic neurosurgery. An optical probe constructed to fit in the Leksell® Stereotactic System was used for measurements along the trajectory and in the targets (globus pallidus internus, subthalamic nucleus, zona incerta, thalamus) during the implantation of deep brain stimulation leads (n = 22). The total backscattered light intensity (TLI) reflecting the grayness of the tissue, and the microvascular perfusion were captured at 128 sites. Heartbeat-synchronized pulsations were found at all perfusion recordings. In 6 sites the perfusion was more than 6 times higher than the closest neighbor indicating a possible small vessel structure. TLI was significantly higher (p < 0.005) and the perfusion significantly lower (p < 0.005) in positions identified as white matter in the respective MRI batch. The measurements imply that LDPM has the potential to be used as an intracerebral guidance tool.

  • 15.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Blomstedt, Patric
    Neurokirurgen Universitetssjukhuset i Umeå.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Richter, Johan
    Neurokirurgen Universitetssjukhuset i Umeå.
    Hariz, Marwan
    Institute of Neurology Queen square, London, UK.
    Intracerebral measurements during DBS-implatation using optical methods2006In: Congress of the European Society for Stereotactic and Funktional Neurosurgery,2006, New York: Springer , 2006Conference paper (Other academic)
    Abstract [en]

       

  • 16.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Blomstedt, Patric
    Inst. för Neurovetenskap, avd för neurokirurgi Umeå Universitetssjukhus.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Richter, Johan
    Inst. för Nervsystem och rörelseorgan, avd för Neurokirurgi Linköpings universitetssjukhus.
    Zsigmond, Peter
    Inst. för Nervsystem och rörelseorgan, avd för Neurokirurgi Linköpings universitetssjukhus.
    Hariz, Marwan
    Inst. för Neurovetenskap, avd för neurokirurgi Umeå Universitetssjukhus samt Institute of Neurology, Queen Square, London, UK.
    Optiska mätningar under stereotaktisk neurokirurgi2006In: Medicinteknikdagarna 2006,2006, 2006Conference paper (Other academic)
    Abstract [sv]

      

  • 17.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fors, Carina
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Antonsson, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A laser Doppler system for intracerebral measurements during stereotactic neurosurgery2007In: Engineering in Medicine and Biology Society, 2007. EMBS 2007, IEEE , 2007, p. 4083-4086Conference paper (Refereed)
    Abstract [en]

    A laser Doppler system for intracerebral measurements during stereotactic and functional neurosurgery is presented. The system comprises a laser Doppler perfusion monitor, an optical probe adapted for the Leksellreg stereotactic system and a personal computer with software for acquisition, data analysis and presentation. The software makes it possible to present both the perfusion and the total backscattered light intensity (TLI) in real-time. During intracerebral measurements, the perfusion signal records the tissue's microcirculation whereas the TLI signal may be used to distinguish between grey and white matter. Evaluation of the system has been done during stereotactic neurosurgery in relation to implantation of deep brain stimulation electrodes. Measurements were made along trajectories towards targets in the deep brain structure as well as in pre-calculated target areas. The measurements show that the system has a potential to be used for intracerebral guidance but further evaluation of the technique is needed.

  • 18.
    Yavari, Nazila
    et al.
    Department of Physics, Lund Institute of Technology, Lund, Sweden.
    Dam, J. S.
    National Laser Centre, CSIR, Pretoria, South Africa.
    Antonsson, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson-Engels, Stefan
    Department of Physics, Lund Institute of Technology, Lund, Sweden.
    In vitro measurements of optical properties of porcine brain using a novel compact device2005In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, no 5, p. 658-666Article in journal (Refereed)
    Abstract [en]

    Knowledge of the optical properties of tissues can be applied in numerous medical and scientific fields, including cancer diagnostics and therapy. There are many different ways of determining the optical properties of turbid media. The paper describes measurements of the optical properties of porcine brain tissue using novel instrumentation for simultaneous absorption and scattering characterisation of small turbid samples. Integrating sphere measurements are widely used as a reference method for determination of the optical properties of relatively thin turbid samples. However, this technique is associated with bulky equipment, complicated measuring techniques, interference compensation techniques and inconvenient sample handling. It is believed that the sphere for some applications can be replaced by a new, compact device, called the combined angular and spatially resolved head sensor, to measure the optical properties of thin turbid samples. The results compare very well with data obtained with an integrating sphere for well-defined samples. The instrument was shown to be accurate to within 12% for μa and 1% for μ s in measurements of intralipid-ink samples. The corresponding variations of data were 17% and 2%, respectively. The reduced scattering coefficient for porcine white matter was measured to be 100 cm−1 at 633 nm, and the value for coagulated brain tissue was 65 cm−1. The corresponding absorption coefficients were 2 and 3 cm−1, respectively.

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