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  • 1.
    Ahn, Henrik Casimir
    et al.
    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.
    Jodal, M.
    Lindhagen, J
    Lundgren, O.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Bestämning av tunntarmsblodflödet med laser Doppler teknik1984In: Läkarsällskapets Riksstämma,1984, 1984Conference paper (Other academic)
  • 2.
    Ahn, Henrik Casimir
    et al.
    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.
    Johansson, K.
    Lindhagen, J.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Förändringar av blodflödet i ventrikeln i samband med mätt med laser Dopplerteknik1984In: Läkarsällskapets Riksstämma,1984, 1984Conference paper (Other academic)
  • 3.
    Ahn, Henrik Casimir
    et al.
    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.
    Johansson, K.
    Lindhagen, J.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Laser Doppler flowmetry in the assessment of gastric blood flow1984In: man. Scand J of Gastroenterology,1984, 1984, p. 98:33-98:33Conference paper (Other academic)
  • 4.
    Ahn, Henrik Casimir
    et al.
    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.
    Lindhagen, J.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Jodal, M.
    Lundgren, O.
    Evaluation of Laser Doppler Flowmetry in the assessment of blood flow in the small intestine1984In: Third World Congress of Microcirculation,1984, 1984Conference paper (Other academic)
  • 5.
    Ahn, Henrik Casimir
    et al.
    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.
    Lindhagen, J
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Jodal, M
    Lundgren, O
    Evaluation of Laser Doppler Flowmetry in the assessment of intestinal blood flow1985In: Gastroenterology, ISSN 0016-5085, E-ISSN 1528-0012, Vol. 4, no 88, p. 951-957Article in journal (Refereed)
    Abstract [en]

      

  • 6.
    Almeida, Eduardo Carlos Venancio de
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Development of a wearable sensor system for real-time control of knee prostheses2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    It was demonstrated in recent studies that Complementary Limb Motion Estimation (CLME) is robust approach for controlling active knee prostheses. A wearable sensor system is then needed to provide inputs to the controller in a real-time platform. In the present work, a wearable sensor system based on magnetic and inertial measurement units (MIMU) together with a simple calibration procedure were proposed. This sensor system was intended to substitute and extend the capabilities of a previous device based on potentiometers and gyroscopes. The proposed sensor system and calibration were validated with an Optical Tracking System (OTS) in a standard gait lab and first results showed that the proposed solution had a performance comparable to similar studies in the literature.

  • 7.
    Alonso, Fabiola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Modeling and simulation of DBS – comparison between leads and stimulation modes2014Conference paper (Other academic)
  • 8.
    Alonso, Fabiola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. University of Applied Sciences and Arts Northwestern Switzerland.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Influence on Deep Brain Stimulation from Lead Design, Operating Mode and Tissue Impedance Changes – A Simulation Study2015In: Brain Disorders and Therapy, ISSN 2168-975X, Vol. 4, no 3, article id 1000169Article in journal (Refereed)
    Abstract [en]

    Background: Deep brain stimulation (DBS) systems in current mode and new lead designs are recently available. To switch between DBS-systems remains complicated as clinicians may lose their reference for programming. Simulations can help increase the understanding.

    Objective: To quantitatively investigate the electric field (EF) around two lead designs simulated to operate in voltage and current mode under two time points following implantation.

    Methods: The finite element method was used to model Lead 3389 (Medtronic) and 6148 (St Jude) with homogenous surrounding grey matter and a peri-electrode space (PES) of 250 μm. The PES-impedance mimicked the acute (extracellular fluid) and chronic (fibrous tissue) time-point. Simulations at different amplitudes of voltage and current (n=236) were performed using two different contacts. Equivalent current amplitudes were extracted by matching the shape and maximum EF of the 0.2 V/mm isolevel.

    Results: The maximum EF extension at 0.2 V/mm varied between 2-5 mm with a small difference between the leads. In voltage mode EF increased about 1 mm at acute compared to the chronic PES. Current mode presented the opposite relationship. Equivalent EFs for lead 3389 at 3 V were found for 7 mA (acute) and 2.2 mA (chronic).

    Conclusions: Simulations showed a major impact on the electric field extension between postoperative time points. This may explain the clinical decisions to reprogram the amplitude weeks after implantation. Neither the EF extension nor intensity is considerably influenced by the lead design.

  • 9.
    Alonso, Fabiola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Latorre, Malcolm
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Göransson, Nathanael
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Zsigmond, Peter
    Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Wårdell, karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Investigation into Deep Brain Stimulation Lead Designs: A Patient-Specific Simulation Study2016In: Brain Sciences, ISSN 2076-3425, E-ISSN 2076-3425, Vol. 6, no 3, p. 1-16Article in journal (Refereed)
    Abstract [en]

    New deep brain stimulation (DBS) electrode designs offer operation in voltage and current mode and capability to steer the electric field (EF). The aim of the study was to compare the EF distributions of four DBS leads at equivalent amplitudes (3 V and 3.4 mA). Finite element method (FEM) simulations (n = 38) around cylindrical contacts (leads 3389, 6148) or equivalent contact configurations (leads 6180, SureStim1) were performed using homogeneous and patient-specific (heterogeneous) brain tissue models. Steering effects of 6180 and SureStim1 were compared with symmetric stimulation fields. To make relative comparisons between simulations, an EF isolevel of 0.2 V/mm was chosen based on neuron model simulations (n = 832) applied before EF visualization and comparisons. The simulations show that the EF distribution is largely influenced by the heterogeneity of the tissue, and the operating mode. Equivalent contact configurations result in similar EF distributions. In steering configurations, larger EF volumes were achieved in current mode using equivalent amplitudes. The methodology was demonstrated in a patient-specific simulation around the zona incerta and a “virtual” ventral intermediate nucleus target. In conclusion, lead design differences are enhanced when using patient-specific tissue models and current stimulation mode.

  • 10.
    Alonso, Fabiola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Comparison of deep brain stimulation systems2014In: Poster Presentations, 2014, Vol. 29, p. 1173-1173, article id Suppl 1Conference paper (Other academic)
    Abstract [en]

    Objective: To quantitatively compare the electric field generated by voltage and current controlled deep brain stimulation systems.

    Background: Traditionally deep brain stimulation (DBS) systems have used voltage control however more recently, current controlled systems have been approved to treat Parkinson's disease and related movement disorders. In the endeavor of understanding the behavior of DBS systems a common approach is the use of computer models suitable to simulate the electric field, current density and other related electric parameters.

    Methods: 2D finite element models based on commercially available DBS systems have been built for each system: I. Model 3389, Medtronic Inc., USA for voltage control; and II. Model 6142, St Jude Medical Inc. USA for current control. The brain tissue has been simplified to homogeneous and isotropic medium. The electric settings correspond to a monopolar configuration, using one of the four contacts available as the active electrode and the outer boundary of the tissue as the reference. Three simulations were performed to mimic different stages of the leads implantation: a) an original stage where the brain tissue is considered as pure gray matter, b) an acute stage that simulates the leakage of cerebral spinal fluid immediately after the electrodes' insertion; and c) a chronic stage mimicking fibrous tissue created around the electrodes some weeks after implantation. Both systems were submitted to the same conditions using as active electrode the third contact from the tip of the lead. The comparison is based on the maximal distance reached by the isopotential of 0.2 V/mm.

    Results: The simulations showed that voltage controlled stimulation systems are more susceptible to changes in the electrical conductivity of the medium i.e. change over time of the tissue around the electrode. This agrees with the adjustment of the stimulation amplitude often necessary a few weeks postoperatively. Current controlled stimulation in turn, presented a linear behavior of the distance reached at different stimulation amplitudes at all stages.

    Conclusions: Current controlled stimulation might be a good option due to its linear behavior over time, nevertheless more studies including a more realistic brain model, different designs of DBS electrodes and different electric parameter, are needed to encourage the use of this type of systems.

  • 11.
    Alonso, Fabiola
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Electric Field Comparison of Deep Brain Stimulation Lead Designs - a Stimulation Study2016Conference paper (Refereed)
  • 12.
    Alonso, Fabiola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Latorre, Malcolm
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Comparison of Three Deep Brain Stimulation Lead Designs under Voltage and Current Modes2015In: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING, 2015, VOLS 1 AND 2 / [ed] David A. Jaffray, Springer, 2015, Vol. 51, p. 1196-1199Conference paper (Refereed)
    Abstract [en]

    Since the introduction of deep brain stimulation (DBS) the technique has been dominated by Medtronic sys-tems. In recent years, new DBS systems have become available for patients, and some are in clinical trials. The present study aims to evaluate three DBS leads operated in either voltage or current mode. 3D finite element method (FEM) models were built in combination with a neuron model for this purpose. The axon diameter was set to D = 5 μm and simulations performed in both voltage (0.5-5 V) and current (0.5-5 mA) mode. The evaluation was achieved based on the distance from the lead for neural activation and the electric field (EF) extension at 0.1 V/mm. The results showed that the neural activation distance agrees well between the leads with an activation distance dif-ference less than 0.5 mm. The shape of the field at the 0.1 V/mm isopotential surface in 3D is mostly spherical in shape around the activated section of the steering lead.

  • 13.
    Alonso, Fabiola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Latorre, Malcolm
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Neural Activation Compared to Electric Field Extension of Three DBS Lead Designs2015Conference paper (Refereed)
    Abstract [en]

    SINCE the introduction of deep brain stimulation (DBS) about 20 years ago, the stimulation technique has been dominated by Medtronic DBS-system setup. In recent years, new DBS systems have become available, of which some are in clinical trials or available to patients [1]. In the present study three different lead designs are investigated via computer simulation:

    Medtronic 3389, St. Jude 6148 and Sapiens SureStim. The aim was to compare the neural activation distance and the electric field (EF) maximum spatial extension for each lead.

    A 3D finite element method model was built using COMSOL Multiphysics 4.4a (COMSOL AB, Stockholm, Sweden) to simulate the electric potential around the DBS lead. Brain tissue was modelled as a homogeneous volume of grey matter (electric conductivity of 0.09 S/m). The electrode-tissue interface was modelled with a 250μm thick peri-electrode space mimicking the fibrous tissue which covers the lead at the chronic stimulation stage (σ = 0.06S/m, equivalent to white matter electric conductivity). The stimulation amplitude was set to 1V in monopolar configuration using C1 electrode or equivalent in all cases. Each simulated electric potential distribution was exported to MatLab (The MathWorks, USA) and used as input to a cable neuron simulation.

    An axon cable model with 21 nodes based on the concept by Åström et al., [2] was set up in MatLab and combined with the exported field distributions. The model considered a 5 μm thick neuron, a pulse width of 60 μs and a drive potential ranging from 0.5 V to 5 V in 0.5 V steps.

    The SureStim lead results showed a shorter neural activation distance and EF extension. The distance to the isolevel of 0.2 V/mm is close to the neural activation distance at each stimulation amplitude, and we conclude that the electric field is a suitable predictor to visualize the stimulated regions.

  • 14. Anderson, C.
    et al.
    Andersson, T.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Changes in skin circulation after microdialysis probe insertion visualized by laser Doppler perfusion imaging1994In: Journal of Investigative Dermatology, ISSN 0022-202X, E-ISSN 1523-1747, Vol. 102, no 5, p. 807-811Article in journal (Refereed)
    Abstract [en]

    Microdialysis makes possible in vivo estimation of endogenous and exogenous substances in the dermal extracellular space. Insertion of the microdialysis probe and its subsequent presence in the skin may affect both the reactivity of the skin test site and the measurement of target substances. Laser Doppler flowmetry is a non-invasive method for estimating cutaneous blood flow. A further development of this technique, laser Doppler perfusion imaging, has been used to study the time course of the circulatory changes caused in the area of microdialysis probe insertion. Laser Doppler perfusion imaging was performed prior to, during, and after microdialysis probe insertion in the skin of the ventral forearm in three subjects. Probe insertion caused an increase in skin blood perfusion in the whole test area. About 15 min after probe insertion, the flare, which is presumed to be of chiefly axon reflex origin, began to subside and the circulatory response could be seen to center around the site of insertion and the tip of the probe. Skin perfusion levels had returned to near normal levels within 60 min. Local anesthesia of the point of guide insertion inhibited the flare, but did not affect circulatory reactivity in the skin nearby. Both microdialysis and laser Doppler perfusion imaging seem to be promising new methods in dermatologic research.

  • 15. Anderson, C.
    et al.
    Svensson, .
    Sjögren, F.
    Andersson, T.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Human in vivo microdialysis technique can be used to measure cytokines in contact reactions.1995In: Current Problems in Dermatology, ISSN 1421-5721, E-ISSN 1662-2944, Vol. 23, p. 121-130Article in journal (Refereed)
  • 16.
    Anderson, Chris
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Lindén, Maria
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    High resolution laser Doppler perfusion imaging for visualisation of changes in skin circulation after microdialysis probe insertion1996In: Jadassohn Centenary Congress,1996, 1996Conference paper (Other academic)
  • 17.
    Anderson, Chris
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Analysis of laser Doppler perfusion images from contact reactions1996In: Jadassohn Centenary Congress,1996, 1996Conference paper (Other academic)
  • 18. Andersson, T.
    et al.
    Anderson, C.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Human in vivo cutaneous microdialysis: Estimation of histamine release in cold urticaria.1995In: Acta Dermato-Venereologica, ISSN 0001-5555, E-ISSN 1651-2057, no 75, p. 343-347Article in journal (Refereed)
    Abstract [en]

    A novel bioanalytical in vivo sampling technique, cutaneous microdialysis, was used to follow the chronology of skin histamine release in 3 patients with cold urticaria and in 2 healthy volunteers. Laser Doppler perfusion imaging was used simultaneously to monitor the skin circulatory response. Microdialysis samples were collected at 10-min intervals and analysed by radioimmunoassay technique. Fifty minutes after probe insertion, the ventral forearm skin in the area of the dialysis membrane was provoked for 5-15 min with a 25 x 40 mm ice cube covered with plastic foil. In the cold urticaria patients, an up to 80-fold increase of histamine was observed, with peak levels 20-30 min after challenge. Histamine levels then fell to reach "baseline" levels within 50 min. In the healthy subjects, the histamine increase was earlier, less pronounced and of shorter duration. Cutaneous microdialysis and laser Doppler imaging offer new possibilities for the chronological multiparameter assessment of inflammatory skin disorders in vivo.

  • 19.
    Andersson-Engels, Stefan
    et al.
    Inst för fysik Lunds Tekniska Högskola.
    Pålsson, S
    Backlund, Erik Olof
    IMT LiU.
    Sturnegk, Patrik
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Lundberg, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Smedby, Örjan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Medical Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology UHL. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Svanberg, K
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    ALA-PpIX Fluorescence and spectroscopy in connection with stereotactic biopsy of human glioblastomas2005In: European Conference on Biomedical Optics,2005, 2005Conference paper (Refereed)
  • 20.
    Andreu-Cabedo, Yasmina
    et al.
    University of Central Lancashire, England.
    Castellano, Pedro
    University of Central Lancashire, England.
    Colantonio, Sara
    National Research Council Italy, Italy.
    Coppini, Giuseppe
    National Research Council Italy, Italy.
    Favilla, Riccardo
    National Research Council Italy, Italy.
    Germanese, Danila
    National Research Council Italy, Italy.
    Giannakakis, Giorgos
    Fdn Research and Technology, Greece.
    Giorgi, Daniela
    National Research Council Italy, Italy.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Marraccini, Paolo
    National Research Council Italy, Italy.
    Martinelli, Massimo
    National Research Council Italy, Italy.
    Matuszewski, Bogdan
    University of Central Lancashire, England.
    Milanic, Matijia
    Norvegian University of Science and Technology, Norway.
    Pascali, Mariantonietta
    National Research Council Italy, Italy.
    Pediaditis, Mattew
    Fdn Research and Technology, Greece.
    Raccichini, Giovanni
    National Research Council Italy, Italy.
    Randeberg, Lise
    Norvegian University of Science and Technology, Norway.
    Salvetti, Ovidio
    National Research Council Italy, Italy.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    MIRROR MIRROR ON THE WALL... AN INTELLIGENT MULTISENSORY MIRROR FOR WELL-BEING SELF-ASSESSMENT2015In: 2015 IEEE INTERNATIONAL CONFERENCE ON MULTIMEDIA and EXPO (ICME), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    The face reveals the healthy status of an individual, through a combination of physical signs and facial expressions. The project SEMEOTICONS is translating the semeiotic code of the human face into computational descriptors and measures, automatically extracted from videos, images, and 3D scans of the face. SEMEOTICONS is developing a multisensory platform, in the form of a smart mirror, looking for signs related to cardio-metabolic risk. The goal is to enable users to self-monitor their well-being status over time and improve their life-style via tailored user guidance. Building the multisensory mirror requires addressing significant scientific and technological challenges, from touch-less data acquisition, to real-time processing and integration of multimodal data.

  • 21.
    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
  • 22.
    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
  • 23.
    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)
  • 24.
    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.

  • 25.
    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.

  • 26.
    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.

  • 27.
    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.

  • 28.
    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.
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Tracking of small blood vessels by a new laser Doppler imaging technique1996In: SPIE-Bios96,1996, 1996Conference paper (Refereed)
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Strömberg, Tomas
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Perfusion responses after local provocation of EMLA analgesized skin1999In: Congress of the International Society for Skin Imaging,1999, 1999Conference paper (Other academic)
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    Ask, Per
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Skogh, Marcus
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Tenland, Torsten
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Undersökning av EKG-elektroders elektriska och mekaniska långtidsegenskaper. Kompletterande studie 11975Report (Other academic)
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Strömberg, Tomas
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Compartmental skin perfusion resposes affected by analgesia1999In: Congress of the International Society for Skin Imaging,1999, 1999Conference paper (Other academic)
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Rikshospitalet, Oslo .
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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    Asker, Claes
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
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  • 41.
    Awan, Z A
    et al.
    Oslo University Hospital.
    Häggblad, Erik
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wester, T
    Oslo University Hospital.
    Kvernebo, M S
    Oslo University Hospital,.
    Halvorsen, P S
    Oslo University Hospital.
    Kvernebo, K
    Oslo University Hospital.
    Diffuse reflectance spectroscopy: Systemic and microvascular oxygen saturation is linearly correlated and hypoxia leads to increased spatial heterogeneity of microvascular saturation2011In: MICROVASCULAR RESEARCH, ISSN 0026-2862, Vol. 81, no 3, p. 245-251Article in journal (Refereed)
    Abstract [en]

    The microvascular oxygen saturation (SmvO(2)) in the skin and tongue (sublingual mucosa) in pigs (n = 6) was characterised using diffuse reflectance spectroscopy (DRS). The correlation between arterial oxygen saturation (SaO(2)) and SmvO(2) as well as the spatial heterogeneity of SmvO(2) was examined during hypoxia. DRS uses shallow-penetrating visible light to assess microvascular oxygen saturation (SmvO(2)) in superficial tissue. Hypoxia was induced by gradual reduction in ventilation or reduction of the inspiratory oxygen fraction. The spatial heterogeneity of SmvO(2) was expressed as the coefficient of variation (CV) of repeated SmvO(2) measurements. Baseline SmvO(2) before interventions was 20.2% (10.3%-38.1%, median with range) in groin skin, 32.9% (13.0%-49.3%) in the ear and 42.2% (32.1%-51.5%) in the tongue. SmvO(2) in the groin was significantly lower than venous oxygen saturation (SvO(2)) (p andlt; 0.05) and SmvO(2) in the tongue (p = 0.03). There was a significant linear correlation between SaO(2) and SmvO(2) in all measuring sites for both interventions (pandlt;0.05). Similarly there was a significant correlation between CV of repeated SmvO(2) measurements and SmvO(2) in all measuring sites for both interventions (p andlt; 0.01). The results from baseline measurements indicate a surprisingly high oxygen extraction in the measurement volume of DRS, especially in the groin skin. A reduction of SmvO(2) with decreasing SaO(2) was found and additionally the results suggest that spatial heterogeneity of microvascular oxygen saturation increases during hypoxia. Microvascular disturbances have been demonstrated in both local vascular diseases and systemic conditions such as shock and sepsis, an assessment of microvascular oxygen saturation using DRS may be useful in the monitoring of the microcirculation in such patients. This study is a part of an ongoing characterization of the DRS technique.

  • 42.
    Balsiger, Fabian
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Brain Tumor Volume Calculation: Segmentation and Visualization Using MR Images2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Glioblastomas are highly aggressive and malignant brain tumors which are difficult to resect totally. The surgical extent of resection constitutes a key role due to its direct influence on the patient’s survival time. To determine the resection extent, the tumor volume on pre-operative and post-operative magnetic resonance (MR) images should be calculated and compared.

    Materials and Methods: An active contour segmentation method was implemented to segment glioblastoma brain tumors on pre-operative T1-contrast enhanced MR images in axial, coronal and sagittal planes by self-developed software. The volume was rendered from the tumor  contours using Delaunay triangulation. Besides the segmentation and volume rendering, a graphical user interface was developed to facilitate the rendering, visualization and volume calculation of the brain tumor. The software was implemented in MATLAB (version 7.2). Two MR image data sets from glioblastoma patients were used and the repeatability and reproducibility of volume calculation was tested. Dimensions of the calculated tumor volume were then compared to the dimensions obtained in Amira® software.

    Results: The tumor volumes for data set 1 and data set 2 were 62.7 and 39.0 cm3, respectively. When tumor was segmented by different users (n=4), the volumes were 62.5 ± 0.3 and 42.6 ± 3.5 cm3. Segmentation errors were seen during the segmentation of data set 2. Mainly under- and over-segmentation due to hypointense MR signals caused by cerebrospinal fluid, or hyperintense MR signals caused by skull bone and weak tumor boundaries led to wrong segmentation results.

    Conclusion: Segmentation using active contours method is able to detect the brain tumor boundaries. The volume rendering and visualization allows the user to explore the tumor tissue and its surrounding interactively. Using the software, tumor volume is precisely calculated.

  • 43.
    Baranowski, Jacek
    et al.
    Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Thoracic and Vascular Surgery in Östergötland.
    Freter, Wolfgang
    Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Thoracic and Vascular Surgery in Östergötland.
    Nielsen, Niels-Erik
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Cardiology UHL.
    Nylander, Eva
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Janerot-Sjöberg, Birgitta
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Wallby, Lars
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Echo-guided presentation of the aortic valve minimises contrast exposure in transcatheter valve recipients2011In: Catheterization and cardiovascular interventions, ISSN 1522-1946, E-ISSN 1522-726X, Vol. 77, no 2, p. 272-275Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES:

    We have developed a method using transthoracic echocardiography in establishing optimal visualization of the aortic root, to reduce the amount of contrast medium used in each patient.

    BACKGROUND:

    During transcatheter aortic valve implantation, it is necessary to obtain an optimal fluoroscopic projection for deployment of the valve showing the aortic ostium with the three cusps aligned in the beam direction. This may require repeat aortic root angiograms at this stage of the procedure with a high amount of contrast medium with a risk of detrimental influence on renal function.

    METHODS:

    We studied the conventional way and an echo guided way to optimize visualisation of the aortic root. Echocardiography was used initially allowing easier alignment of the image intensifier with the transducer's direction.

    RESULTS:

    Contrast volumes, radiation/fluoroscopy exposure times, and postoperative creatinine levels were significantly less in patients having the echo-guided orientation of the optimal fluoroscopic angles compared with patients treated with the conventional approach.

    CONCLUSION:

    We present a user-friendly echo-guided method to facilitate fluoroscopy adjustment during transcatheter aortic valve implantation. In our series, the amounts of contrast medium and radiation have been significantly reduced, with a concomitant reduction in detrimental effects on renal function in the early postoperative phase.

  • 44.
    Behm, Pascal
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Institute for Medical ans Analytical Technologies, University of Northwestern Switzerland.
    Experimental set-up for near infrared fluorescence measurements during surgery2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In case a tumour grows in a tissue close to the lymphatic system, biopsies of the first draining lymph nodes connected to the tumour, also known as sentinel lymph nodes, allow determining if the cancer has already metastasized. Lymph node mapping is used in oncology surgery to find the patients lymph nodes connected to the tumour. The fluorescence marker indocyanine green (ICG) has shown successful results to trace the lymph nodes and arise to replace the currently used radioactive tracers. Because the ICG fluorescence is in the near infrared region and not visible to the human eye, imaging systems are used to visualise the fluorescence. A preliminary spectroscopy measurement system was developed at the Department of Biomedical Engineering, Linköping University. The aim of this thesis was to develop a combined spectroscopy and imaging set-up for simultaneous recordings of ICG fluorescence and suggest further developments.

    The combined system consisted of a fibre-optical based spectroscopy system together with a camera imaging system. An optical phantom that mimicked breast tissue (μs = 4.66 mm-1) was developed for the measurements. Phantoms with different ICG concentrations of 6.45 μM, 64.5 μM and 645 μM simulated different concentrations of fluorescence dye in the lymph system. The set-up and the settings of the devices were adjusted to enable simultaneous measurements with both systems. The phantoms were solidified with agar to measure the fluorescence decay (photobleaching) of ICG. To simulate a lymph node deep in the tissue, a tube containing pure ICG was covered with different layer thicknesses of breast tissue-like phantom.

    Measurements at the same time with both systems were possible when the probe was positioned in an 80 degree angle with 5 mm distance relative to the phantom surface and the camera in 10 cm distance with a 30 degree angle. To visualise the ICG fluorescence emission with the excitation light (4 mW) and an integration time of 600 ms was necessary for the camera. Higher laser power caused saturation in the spectrometer. The spectroscopy measurements and camera images showed maximum fluorescence intensity at an optimal ICG concentration (10-16 μM) in the phantom. Also the photobleaching measurements showed to be dependent on the ICG concentration and associated with the optimal concentration. ICG concentrations equal and lower than the optimal concentration decayed with exposure to the excitation light. The fluorescence intensity of higher concentrations initially increased and decayed after reaching a maximum intensity when exposed to the excitation light. The detection depth in the simulated tissue was limited to 0.3 mm for spectroscopy. A detection depth of 2 mm was achieved with the camera while using the maximum excitation power of 50 mW and integration time of 700 ms.

    Simultaneous measurements were possible with the set-up on the same phantom. An optimal concentration of ICG was found for the developed phantom. The ICG fluorescence intensity was concentration dependent and showed a relatively slow photobleaching. The fibre-optical based spectroscopy system was able to measure low ICG emissions. Subtracting the background spectrum of surrounding tissue might increase the detection of weak ICG signals in depth. High excitation power and an increased integration time were needed to record ICG fluorescence emission with the camera. The obtained results allowed suggestions for the further improvement of set-up and its intraoperative use.

  • 45.
    Benosman, Mourad
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology. Tlemcen University, Algeria.
    Bereksi-reguig, Fethi
    Tlemcen University, Algeria.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Analysis of ECG-trunk muscle signal amplitude and heart rate relationship2013In: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 37, no 7, p. 449-455Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to investigate if bioelectrical signals, generated from trunk muscles identified in an electrocardiogram (ECG) signal presented in this paper as ECG-Trunk Muscles Signals amplitude (Ecg-TMSA) are correlated with Heart rate (HR) during different levels of physical activity and also if Ecg-TMSA is not influenced by mental activity. HR and Ecg-TMSA were derived from ECG in 14 subjects when walking and jogging at different treadmill velocities from 4–10 (km h−1). The mean relationship for all 14 subjects was HR = (42.3 ± 0.2) + (45.3 ± 2.8) Ecg-TMSA, r2 = 0.91. The result of one individual data points example for a 21 min experiment was (r2 = 0.93, p < 0.0001, n = 336). The obtained results show a linear relationship between Ecg-TMSA and HR. Moreover, the Ecg-TMSA was not affected by mental activity

  • 46.
    Benosman, Mourad
    et al.
    Abou Bekr Belkaid university, Tlemcen, Algeria.
    Bereksi-reguig, Fethi
    Abou Bekr Belkaid university, Tlemcen, Algeria.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Distingush physical activity from mental stress analyzing ECG signals with overlayed non cardiac muscle activity2012In: BIOMEIC'12, 2012Conference paper (Other academic)
  • 47.
    Benosman, Mourad
    et al.
    Abou Bekr Belkaid university, Tlemcen, Algeria.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Bereksi-reguig, Fethi
    Abou Bekr Belkaid university, Tlemcen, Algeria.
    Measuring muscle activity with ECG electrodes to distinguish physical activity from mental stress2012Conference paper (Other academic)
  • 48.
    Blomstedt, Patric
    et al.
    Umeå University, Sweden .
    Fytagoridis, Anders
    Umeå University, Sweden .
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Linder, Jan
    Umeå University, Sweden .
    Forsgren, Lars
    Umeå University, Sweden .
    Hariz, Marwan I.
    Umeå University, Sweden .
    Unilateral caudal zona incerta deep brain stimulation for Parkinsonian tremor2012In: Parkinsonism & Related Disorders, ISSN 1353-8020, E-ISSN 1873-5126, Vol. 18, no 10, p. 1062-1066Article in journal (Refereed)
    Abstract [en]

    Background: The subthalamic nucleus is currently the target of choice in deep brain stimulation (DBS) for Parkinsons disease (PD), while thalamic DBS is used in some cases of tremor-dominant PD. Recently, a number of studies have presented promising results from DBS in the posterior subthalamic area, including the caudal zona incerta (cZi). The aim of the current study was to evaluate cZi DBS in tremor-dominant Parkinsons disease. less thanbrgreater than less thanbrgreater thanMethods: 14 patients with predominately unilateral tremor-dominant PD and insufficient relief from pharmacologic therapy were included and evaluated according to the motor part of the Unified Parkinson Disease Rating Scale (UPDRS). The mean age was 65 +/- 6.1 years and the disease duration 7 +/- 5.7 years. Thirteen patients were operated on with unilateral cZi DBS and 1 patient with a bilateral staged procedure. Five patients had non-L-dopa responsive symptoms. The patients were evaluated on/off medication before surgery and on/off medication and stimulation after a minimum of 12 months after surgery. less thanbrgreater than less thanbrgreater thanResults: At the follow-up after a mean of 18.1 months stimulation in the off-medication state improved the contralateral UPDRS III score by 47.7%. Contralateral tremor, rigidity, and bradykinesia were improved by 82.2%, 34.3%, and 26.7%, respectively. Stimulation alone abolished tremor at rest in 10 (66.7%) and action tremor in 8 (533%) of the patients. less thanbrgreater than less thanbrgreater thanConclusion: Unilateral cZi DBS seems to be safe and effective for patients with severe Parkinsonian tremor. The effects on rigidity and bradykinesia were, however, not as profound as in previous reports of DBS in this area.

  • 49.
    Briers, David
    et al.
    University of Kingston, England .
    Duncan, Donald D.
    Portland State University, OR USA .
    Hirst, Evan
    Callaghan Innovat, New Zealand .
    Kirkpatrick, Sean J.
    Michigan Technology University, MI USA .
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Steenbergen, Wiendelt
    University of Twente, Netherlands .
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Thompson, Oliver B.
    Callaghan Innovat, New Zealand .
    Laser speckle contrast imaging: theoretical and practical limitations2013In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 18, no 6Article in journal (Refereed)
    Abstract [en]

    When laser light illuminates a diffuse object, it produces a random interference effect known as a speckle pattern. If there is movement in the object, the speckles fluctuate in intensity. These fluctuations can provide information about the movement. A simple way of accessing this information is to image the speckle pattern with an exposure time longer than the shortest speckle fluctuation time scale-the fluctuations cause a blurring of the speckle, leading to a reduction in the local speckle contrast. Thus, velocity distributions are coded as speckle contrast variations. The same information can be obtained by using the Doppler effect, but producing a two-dimensional Doppler map requires either scanning of the laser beam or imaging with a high-speed camera: laser speckle contrast imaging (LSCI) avoids the need to scan and can be performed with a normal CCD- or CMOS-camera. LSCI is used primarily to map flow systems, especially blood flow. The development of LSCI is reviewed and its limitations and problems are investigated. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

  • 50.
    Brydegaard, Mikkel
    et al.
    Department of Physics, Lund University.
    Haj-Hosseini, Neda
    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.
    Andersson-Engels, Stefan
    Department of Physics, Lund University.
    Photobleaching-Insensitive Fluorescence Diagnostics in Skin and Brain Tissue2011In: IEEE Photonics Journal, ISSN 1943-0655, Vol. 3, no 3, p. 407-421Article in journal (Other academic)
    Abstract [en]

    In this paper, we investigate the possibility of using accurate prediction models for the prediction of protoporphyrin bleaching dynamics to achieve photobleaching-insensitive methods to improve the evaluation of data in an existing clinical fluorescence-guided resection technique. To simulate the scenario, measurements were carried out in vivo on skin of healthy volunteers using a compact fiber-based fluorescence spectroscopy system. We have developed an effective method for the parameterization of sequences of bleaching spectra. We analyze convergence and decay rates with respect to initial conditions and excitation irradiance. We also discuss the consequences and the potential for bleaching-insensitive measurements and their applicability in a few examples from in vivo open brain surgery.

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