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  • 151.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Medicine and Health Sciences.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Milos, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Optical guidance for stereotactic brain tumor biopsy procedures-preliminary clinical evaluation2017Conference paper (Refereed)
    Abstract [en]

    During stereotactic biopsy on suspected tumors in the brain, tissue samples are harvested to determine the malignancy. To provide guidance for finding the diagnostic tumor sites and to avoid vessel rupture, an application specific probe was developed. The setup incorporated spectroscopy for detection of 5-aminolevulinic acid induced protoporphyrin (PpIX) fluorescence and blood flow using laser Doppler flowmetry. The PpIX fluorescence was significantly different in the tumor compared to the gliotic marginal zone (p < 0.05). In conclusion, the systems made real-time tumor detection and vessel tracking possible. Moreover, the autofluorescence and blood perfusion could be studied in the tumor.

  • 152.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Olivecrona, Magnus
    Department of Neurosurgery, Umeå University.
    Hillman, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fluorescence guided spectroscopy versus fluorescence microscopy for brain tumor resection2013Conference paper (Other academic)
  • 153.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fluorescence spectroscopy for ALA-guided glioblastoma resection using a fiber-optical probe2012Conference paper (Refereed)
  • 154.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Medicine and Health Sciences.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Medicine and Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Photodiagnostics in Brain Tumor Surgery2014In: Medicinteknikdagarna, Göteborg, 14-16 oktober, 2014: Sammanfattningar, Göteborg: Svensk förening för medicinsk teknik och fysik , 2014Conference paper (Refereed)
    Abstract [en]

    Since getting approved for clinical application in neurosurgery 5-aminolevulinic acid (ALA), that is a fluorescence contrast agent, has attracted the interest of many neurosurgical clinics to implement it in their surgical routine. ALA naturally exists in the body and the external administration of the substance induces accumulation of a fluorophore known as protoporphyrin IX (PpIX) in the malignant cells due to a broken blood brain barrier and the altered enzyme levels in the brain tumor. The detection and visualization of PpIX in the clinical routine is conventionally performed using a modified neuro surgical microscope. As a complementary technique for detection of ALA-induced fluorescence and to perform objective and quantitative measurements, our group has developed a spectroscopy system adapted to the equipment in the operating room. The system includes a hand-held fiber optic probe which can be integrated in the neuronavigation and stereotactic systems. The main advantages of the system are the ease of use, high sensitivity, quantitative fluorescence detection and the possibility of applying a low dose of fluorescence contrast agent while obtaining equally reliable results as with the high dose. In this contribution we present our experience, gains and challenges from implementation of the system during brain tumor surgery in forty adult patients. The methods and systems are currently being adapted for implementation during operations of pediatric brain tumors.

  • 155.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Health Sciences.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Quantitative ALA photodiagnostics in Neurosurgery2014Conference paper (Other academic)
  • 156.
    Haj-Hosseini, Neda
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    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.
    Compensation of blood interference in fiber-optical based fluorescence guided resection of brain tumor2011Conference paper (Refereed)
  • 157.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Stepp, Herbert
    Ludwig Maximilians Universitet, München.
    Markwardt, Niklas
    Ludwig Maximilians Universitet, München.
    Gimm, Oliver
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Shabo, Ivan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Optical biopsy during thyroid and parathyroid surgery2015Conference paper (Refereed)
  • 158.
    Haj-Hosseini, Neda
    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.
    Optical Coherence Tomography as a Future Modality in Digital Pathology2015Conference paper (Other academic)
  • 159.
    Hass, Ursula
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Department of Health and Society, Center for Medical Technology Assessment.
    Ask, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Competence Centre NIMED and it's graduate education - collaboration between university and industry.1999In: Ann Int Conf of the IEEE Engineering in Medicine and Biology Society,1999, 1999Conference paper (Other academic)
  • 160. Hellem, S.
    et al.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Bone blood flow1989In: Laser-Doppler Blood Flowmetry, Kluwer Academic Publishers, 1989Chapter in book (Other academic)
    Abstract [en]

        

  • 161. Hellem, S.
    et al.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Use of single fiber laser Doppler flowmetry in measuring local blood flow in cancellous bone1986In: XIV International Conference of European Society for Microcirculation,1986, 1986Conference paper (Other academic)
  • 162.
    Hemm, Simone
    et al.
    Institute for Medical and Analytical Technologies (IMA), FHNW, Switzerland.
    Richter, Johan C.O.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Optical measurements for guidance during deep brain stimulation implantation2011Conference paper (Refereed)
  • 163.
    Hemm, Simone
    et al.
    University of Applied Sciences Northwestern Switzerland, Institute for Medical and Analytical Technologies, Muttenz, Switzerland.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools2010In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 48, no 7, p. 611-624Article in journal (Refereed)
    Abstract [en]

    Deep brain stimulation (DBS) has become increasingly important for the treatment and relief of neurological disorders such as Parkinson's disease, tremor, dystonia and psychiatric illness. As DBS implantations and any other stereotactic and functional surgical procedure require accurate, precise and safe targeting of the brain structure, the technical aids for preoperative planning, intervention and postoperative follow-up have become increasingly important. The aim of this paper was to give and overview, from a biomedical engineering perspective, of a typical implantation procedure and current supporting techniques. Furthermore, emerging technical aids not yet clinically established are presented. This includes the state-of-the-art of neuroimaging and navigation, patient-specific simulation of DBS electric field, optical methods for intracerebral guidance, movement pattern analysis, intraoperative data visualisation and trends related to new stimulation devices. As DBS surgery already today is an important technology intensive domain, an "intuitive visualisation" interface for improving management of these data in relation to surgery is suggested.

  • 164.
    Hemm, Simone
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Richter, Johan
    Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL. Linköping University, Department of Biomedical Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Laser doppler for guidance during DBS-typical optical trajectories toward Vim and STN2012Conference paper (Other academic)
  • 165.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Institute for Medical and Analytical Technologies, University of Applied Sciences and Art Northwestern Switzerland, Basel.
    Patient-specific electric field simulations and acceleration measurements for intraoperative test-stimulations2014Conference paper (Other academic)
  • 166.
    Hemm-Ode, Simone
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland.
    Pison, Daniela
    Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland.
    Alonso, Fabiola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Shah, Ashesh
    Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland.
    Coste, Jérôme
    Université Clermont Auvergne, Université d’Auvergne, EA 7282, Image Guided Clinical Neurosciences and Connectomics (IGCNC), Clermont-Ferrand, France; Service de Neurochirurgie, Hôpital Gabriel-Montpied, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France.
    Lemaire, Jean-Jacques
    Université Clermont Auvergne, Université d’Auvergne, EA 7282, Image Guided Clinical Neurosciences and Connectomics (IGCNC), Clermont-Ferrand, France; Service de Neurochirurgie, Hôpital Gabriel-Montpied, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Patient-Specific Electric Field Simulations and Acceleration Measurements for Objective Analysis of Intraoperative Stimulation Tests in the Thalamus2016In: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 10, p. 1-14, article id 577Article in journal (Refereed)
    Abstract [en]

    Despite an increasing use of deep brain stimulation (DBS) the fundamental mechanisms of action remain largely unknown. Simulation of electric entities has previously been proposed for chronic DBS combined with subjective symptom evaluations, but not for intraoperative stimulation tests. The present paper introduces a method for an objective exploitation of intraoperative stimulation test data to identify the optimal implant position of the chronic DBS lead by relating the electric field (EF) simulations to the patient-specific anatomy and the clinical effects quantified by accelerometry. To illustrate the feasibility of this approach, it was applied to five patients with essential tremor bilaterally implanted in the ventral intermediate nucleus (VIM). The VIM and its neighborhood structures were preoperatively outlined in 3D on white matter attenuated inversion recovery MR images. Quantitative intraoperative clinical assessments were performed using accelerometry. EF simulations (n = 272) for intraoperative stimulation test data performed along two trajectories per side were set-up using the finite element method for 143 stimulation test positions. The resulting EF isosurface of 0.2 V/mm was superimposed to the outlined anatomical structures. The percentage of volume of each structure’s overlap was calculated and related to the corresponding clinical improvement. The proposed concept has been successfully applied to the five patients. For higher clinical improvements, not only the VIM but as well other neighboring structures were covered by the EF isosurfaces. The percentage of the volumes of the VIM, of the nucleus intermediate lateral of the thalamus and the prelemniscal radiations within the prerubral field of Forel increased for clinical improvements higher than 50% compared to improvements lower than 50%. The presented new concept allows a detailed and objective analysis of a high amount of intraoperative data to identify the optimal stimulation target. First results indicate agreement with published data hypothesizing that the stimulation of other structures than the VIM might be responsible for good clinical effects in essential tremor. (Clinical trial reference number: Ref: 2011-A00774-37/AU905)

  • 167.
    Hemm-Ode, Simone
    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.
    Correlation between laser Doppler measurements and anatomy during deep brain stimulation surgery2012In: Biomedical Engineering, ISSN 0006-3398, E-ISSN 1573-8256, Vol. 57Article in journal (Refereed)
    Abstract [en]

    Introduction

    In Deep Brain Stimulation (DBS) the save, accurate and precise electrode implantation is essential. We have previously presented an optical technique for intra-operative measurements during DBS implantation. The aim of the present study was to establish the link between anatomy and total light intensity (TLI, the greyness of the tissue) and microvascular perfusion recordings.

    Methods

    Twelve patients (6 subthalamic nucleus STN, 6 ventral intermediate nucleus Vim) referred for unilateral or bilateral DBS-implantation for the treatment of essential tremor or Parkinson’s disease were included in the study. Stereotactic CT imaging was used for planning of the trajectories and targets (n=22). Measurement of the TLI and the microvascular perfusion were performed in mm-steps along the trajectory. TLI and perfusion data were post-processed to “optical trajectories” ranging from the cortex towards the target. These were compared with anatomy along the final trajectories by the use of a brain atlas and Surgiplan.

    Results

    Post-processing of the TLI signal showed a clear relationship with anatomy. Characteristic median curves were determined. The curve normally started with low values for STN and Vim patients when in cortex. When the probe entered white matter the TLI increased and stayed at this level until it passed in the vicinity to putamen, caudate nucleus or ventricle. A statistical significant difference (p<0.05) could be shown between white matter and putamen and between white matter and the target area. Concerning microvascular perfusion, high values were often seen in the cortex and low ones in white matter (significant statistical difference: p<0.05). In one case a small bleeding was suspected during surgery with the optical technique. This was confirmed with post-operative CT.

    Conclusion

    In summary the optical technique show promising results and typical trajectories were defined towards the STN and Vim, but further evaluation is necessary in order to refine the “optical bar codes” towards specific DBS-targets.

  • 168.
    Henricson, Joakim
    et al.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Droog Tesselaar, Erik
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Persson, Karin
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Burn Unit . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Assessment of microvascular function by study of the dose‐response effects of iontophoretically applied drugs (acetylcholine and sodium nitroprusside): Methods and comparison with in vitro studies2007In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 73, no 2, p. 143-149Article in journal (Refereed)
    Abstract [en]

    Current knowledge about vascular function stems mainly from pharmacological in vitro studies using mounted vascular strips on a strain gauge. We know of no paper that has systematically examined the possibility of assessing the conventional dose–response effects of iontophoresis and laser Doppler investigation of vasoactive substances and compared those relations to data obtained from strips mounted on a strain gauge.

    We used the vasoactive substances acetylcholine (endothelium dependent) and sodium nitroprusside (endothelium independent) and an antagonist (atropine) to enable further investigations in the receptor physiology of iontophoresis.

    Dose–response curves from the iontophoresis experiments showed close similarity to those obtained by vascular strips mounted on a strain gauge. The coefficient of variation (CV) of the dose–response factors found in iontophoresis (both inter and intra experimental variability) was low. The iontophoretic effective dose of 50% (ED50) for acetylcholine and nitroprusside had only CVs of 25% and 26%, respectively, compared with 71% and 77% for the vascular strips. Acetylcholine-induced response was antagonized by iontophoresis of atropine. Contrary to expectations, this antagonism was not competitive.

    The results show that iontophoresis in combination with laser Doppler technology produces reproducible and reliable dose–response curves that picture the vascular effects of vasoactive drugs.

  • 169.
    Henricson, Joakim
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery.
    Nilsson, A.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Sjöberg, Folke
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Sub-epidermal imaging using polarized light spectroscopy for assessment of cutaneous microvascular function during iontophoresis of nor-adrenaline and phenylephrine2007In: 8th World Congress for microcirculation,2007, 2007Conference paper (Refereed)
  • 170.
    Henricson, Joakim
    et al.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Nilsson, Anders
    Berzelius Clinical Research Center AB.
    Tesselaar, Erik
    Berzelius Clinical Research Center AB.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Burn Unit . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Tissue viability imaging: Microvascular response to vasoactive drugs induced by iontophoresis2009In: Microvascular Research, ISSN 0026-2862, Vol. 78, no 2, p. 199-205Article in journal (Refereed)
    Abstract [en]

    When one is studying the physiology of the cutaneous microcirculation there is a need for relevant non-invasive and versatile techniques. In this study we used a new optical device, the tissue viability imager (TiVi), to map changes in cutaneous microvascular concentrations of red blood cells during iontophoresis of vasoactive substances (noradrenaline (NA) and phenylephrine (Phe) for vasoconstriction and acetylcholine (ACh) and sodium nitroprusside (SNP) for vasodilatation). We aimed to present data both individually and pooled, using a four-variable logistic dose response model that is commonly used in similar in vitro vascular studies. The accuracy of the TiVi was also investigated by calculating the coefficient of variation and comparing it with similar tests previously done using laser Doppler imaging.

    Tests were also performed using the TiVi and LDPI simultaneously to further compare the two methods. Results showed that the TiVi is capable of quantifying vascular responses to iontophorised noradrenaline and phenylephrine without the need to increase background flow first. Fitting the TiVi data to the dose response model resulted in ED50-values with narrow confidence intervals and acceptable r2 values. Mean ED50-values for the TiVi did not differ significantly from similar values obtained using laser Doppler.

    Results further seem to suggest that when the blood perfusion increases during vasodilatation in skin the initial phase relies mainly on an increase in red blood cell concentration whereas the further perfusion increase is due to an increase in red blood cell velocity.

  • 171.
    Henricson, Joakim
    et al.
    Linköping University, Department of Biomedicine and Surgery, Division of surgery. Linköping University, Faculty of Health Sciences.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Sjöberg, Folke
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Microvascular response to iontophoretically applied acetylcholine investigated by Tissue Viability Imaging2006Conference paper (Other academic)
  • 172.
    Henricson, Joakim
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Sjöberg, Folke
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Anderson, Chris
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    The polarization scectroscopic camera allows assessment of vasoconstriction after topical application of clobetasol2007In: 16th congress of the European Academy of Dermatology and Venerology,2007, 2007Conference paper (Refereed)
  • 173.
    Hirbayashi, Hidehiro
    et al.
    Nara Medical University, Kashihara , Japan.
    Hariz, Marwan
    Umeå University.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Blomstedt, Patric
    Umeå University.
    Impact of Parameters of Radiofrequency Coagulation on Volume of Stereotactic Lesion inPallidotomy and Thalamotomy2012In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 90, no 5, p. 307-315Article in journal (Refereed)
    Abstract [en]

    Background: One of the many reasons why lesional surgery for movement disorders has been more or less abandoned may have been the difficulty in predicting the shape and size of the stereotactic radiofrequency (RF) lesion. Objectives: To analyse the contribution of various RF coagulation parameters towards the volume of pallidotomies and thalamotomies. Methods: The relationship between temperature of coagulation, length of coagulated area and duration of coagulation on the one hand, and lesion volume on the other was retrospectively evaluated. Lesion diameters were measured on stereotactic thin-slice CT and MRI scans, and volumes of lesions were calculated concerning 36 pallidotomies and 14 thalamotomies in 46 patients who were operated using the same RF generator and same RF electrode. Results: The coagulation temperature, length of coagulated area and duration of coagulation were all correlated to the lesion volume. However, for a given length of coagulated area, the lesion´s size was most strongly influenced by the temperature. Despite this clear correlation, and the relatively homogenous coagulation parameters, the lesions’ volumes were markedly scattered. Conclusions: The volume of the stereotactic RF lesions could be correlated with the coagulation parameters, especially the temperature, at a group level, but could not be predicted in individual patients based solely on the RF coagulation parameters.

  • 174. Humeau, A
    et al.
    Nilsson, Henrik
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Steenbergen, W
    Strömberg, Tomas
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Laser Doppler perfusion monitoring and imaging: Novel approaches2007In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 45, no 5, p. 421-435Article in journal (Refereed)
    Abstract [en]

    Laser Doppler flowmetry (LDF) is a non invasive method enabling the monitoring of microvascular blood flow, a very important marker of tissue health. This article gives an overview on the concept of LDF for microvascular perfusion monitoring and imaging. It first describes the theoretical background of the technique. Then, the benefits of LDF signal processing are shown through clinical examples: use of time-frequency representations and wavelets. Afterwards, the paper introduces novel approaches of velocity components. For that purpose, a work providing the determination of the velocities relative contribution in physiologically relevant units (mm/s) is presented. Imaging perfusion is also reviewed through methods based on laser speckle. The most prominent disadvantage of the latter devices being the time needed to produce a perfusion image, solutions are proposed in the last part of the paper. © International Federation for Medical and Biological Engineering 2007.

  • 175.
    Häggblad, Erik
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    In Vivo Diffuse Reflectance Spectroscopy of Human Tissue: From Point Measurements to Imaging2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents the non-invasive use of diffuse reflectance spectroscopy (DRS) to provide information about the biochemical composition of living tissue. During DRS measurements, the incident, visible light is partially absorbed by chromophores but also scattered in the tissue before being remitted.

    Human skin and heart, the main tissue objects in this thesis, are dependent on a sufficient inflow of oxygenized blood, and outflow of metabolic byproducts. This process could be monitored by DRS using the spectral fingerprints of the most important tissue chromophores, oxyhemoglobin and deoxyhemoglobin.

    The Beer-Lambert law was used to produce models for the DRS and has thus been a foundation for the analyses throughout this work. Decomposition into the different chromophores was performed using least square fitting and tabulated data for chromophore absorptivity.

    These techniques were used to study skin tissue erythema induced by a provocation of an applied heat load on EMLA-treated skin. The absorbance differences, attributed to changes in the hemoglobin concentrations, were examined and found to be related to, foremost, an increase in oxyhemoglobin.

    To estimate UV-induced border zones between provoked and nonprovoked tissue a modified Beer-Lambert model, approximating the scattering effects, was used. An increase of chromophore content of more than two standard deviations above mean indicated responsive tissue. The analysis revealed an edge with a rather diffuse border, contradictory to the irradiation pattern.

    Measuring in the operating theater, on the heart, it was necessary to calculate absolute chromophore values in order to assess the state of the myocardium. Therefore, a light transport model accounting for the optical properties, and a calibrated probe, was adopted and used. The absolute values and fractions of the chromophores could then be compared between sites and individuals, despite any difference of the optical properties in the tissue.

    A hyperspectral imaging system was developed to visualize the spatial distribution of chromophores related to UV-provocations. A modified Beer-Lambert approximation was used including the chromophores and a baseline as an approximate scattering effect. The increase in chromophore content was estimated and evaluated over 336 hours.

    In conclusion, advancing from a restricted Beer-Lambert model, into a model estimating the tissue optical properties, chromophore estimation algorithms have been refined progressively. This has allowed advancement from relative chromophore analysis to absolute values, enabling precise comparisons and good prediction of physiological conditions.

    List of papers
    1. Reflection Spectroscopy of Analgesized Skin
    Open this publication in new window or tab >>Reflection Spectroscopy of Analgesized Skin
    Show others...
    2001 (English)In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 62, no 3, p. 392-400 Article in journal (Refereed) Published
    Abstract [en]

    Analgesized skin, when subjected to heat stimuli, responds by increasing skin perfusion. This response does not originate from increased perfusion in superficial capillaries, but rather in the deeper lying vessels. The aim of this study was to assess changes in blood chromophore content, measured by reflection spectroscopy, in relation to the perfusion increase, especially regarding the chromophores oxyhemoglobin and deoxyhemoglobin. Eleven normal subjects were treated with analgesic cream (EMLA) and placebo for 20, 40, 60, 120, and 180 min. Individual reactions to local heating were classified as responses if the change in reflection data or the change in perfusion, as measured by laser Doppler blood flowmetry, exceeded 2 standard deviations of normal variation. The increase in blood perfusion or in blood content gave rise to an increased absorption, interpreted as an increase due mainly to the chromophore oxyhemoglobin. The number of responses increased with increased treatment time for EMLA-treated areas. In general, there was a good agreement between both methods; 44 of 55 classifications coincided for the two methods used. In conclusion, analgesized forearm skin, which had been exposed to local heating, responded with an elevated perfusion consisting of oxygenated blood. This strengthens the hypothesis that the flow increase occurs through dilatation of larger deeper lying skin vessels and not in the capillaries.

    Place, publisher, year, edition, pages
    ScienceDirect, 2001
    Keywords
    spectroscopy; laser Doppler flowmetry; EMLA; hemoglobin; analgesia; heat stimuli; skin microcirculation
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-15184 (URN)10.1006/mvre.2001.2358 (DOI)
    Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2017-12-14Bibliographically approved
    2. A diffuse reflectance spectroscopic study of UV-induced erythematous reaction across well-defined borders in human skin
    Open this publication in new window or tab >>A diffuse reflectance spectroscopic study of UV-induced erythematous reaction across well-defined borders in human skin
    Show others...
    2010 (English)In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 16, no 3, p. 283-290Article in journal (Refereed) Published
    Abstract [en]

    Introduction The colour of tissue is often of clinicaluse in the diagnosis of tissue homeostasis andphysiological responses to various stimuli.Determining tissue colour changes and borders,however, often poses an intricate problem and visualexamination, constituting clinical praxis, does notallow them to be objectively characterized orquantified. Demands for increased inter- and intraobserverreproducibility have been incentives for theintroduction of objective methods and techniques fortissue colour (e.g. erythema) evaluation. The aim ofthe present paper was to study the border zone of anUVB provoked erythematous response of humanskin in terms of blood volume and oxygenationmeasured by means of diffuse reflectancespectroscopy using a commercial probe.

    Material and Methods A provocation model, basedon partial masking of irradiated skin areas, definestwo erythema edges at every skin site responding tothe UV irradiation. In every subject, 5 test sites wereexposed with a constant UV light irradiance (14mW/cm2), but with different exposures times (0, 3,6, 9, 12 seconds). An analysis of the spectral datameasured across the two edges was performed for every scan line. The oxygenized and deoxygenizedhemoglobin contents were estimated in everymeasurement point, using a modified Beer-Lambertmodel.

    Results The fit of the experimental data to the model derived by the modified Beer-Lambert law was excellent (R2>0.95). Analyzing data for the chromophore content showed that the erythematous response in provoked areas is dominated by the increase in oxyhemoglobin. The width for the left and right border zone was estimated to 1.81±0.93 mm and 1.90±0.88 mm respectively (M±SD). The unprovoked area between the two edges was estimated to 0.77±0.68 mm.

    Conclusion While the chosen data analysis performed satisfactory, the ability of the probe design to differentiate spatial aspects of a reaction with abrupt borders was found to be suboptimal resulting in a probable overestimation of the erythematous edge slope. Probe modification or imaging are possible solutions.

    Place, publisher, year, edition, pages
    Wiley, 2010
    Keywords
    Erythema, UV, Spectroscopy, Oxygenation, Human skin
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-15185 (URN)10.1111/j.1600-0846.2010.00424.x (DOI)
    Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2017-12-14Bibliographically approved
    3. Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting
    Open this publication in new window or tab >>Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting
    Show others...
    2008 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 13, no 5, p. 054030-Article in journal (Refereed) Published
    Abstract [en]

    We present a study using a method able to assess tissue oxygenation, taking into account the absorption and the level of scattering in myocardial tissue using a calibrated fiber optic probe. With this method, interindividual comparisons of oxygenation can be made despite varying tissue optical properties during coronary artery bypass grafting (CABG). During CABG, there are needs for methods allowing continuous monitoring and prediction of the metabolism in the myocardial tissue. 14 patients undergoing CABG are investigated for tissue oxygenation during different surgical phases using a handheld fiber optic spectroscopic probe with a source-detector distance of less than 1 mm. The probe is calibrated using a light transport model, relating the absorption and reduced scattering coefficients (mu(a) and mu()(s)) to the measured spectra. By solving the inverse problem, absolute measures of tissue oxygenation are evaluated by the sum of oxygenized hemoglobin and myoglobin. Agreement between the model and measurements is obtained with an average correlation coefficient R-2 of 0.96. Oxygenation is found to be significantly elevated after aorta cross-clamping and cardioplegic infusion, as well as after reperfusion, compared to a baseline (p < 0.05). Tissue oxygenation decreases during cardiac arrest and increases after reperfusion.

    Keywords
    diffuse reflectance spectroscopy, oxygenation, myocardium, tissue, coronary artery bypass grafting
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-16251 (URN)10.1117/1.2976433 (DOI)
    Note

    Original Publication: Erik Häggblad, Tobias Lindbergh, Daniel Karlsson, Henrik Casimir-Ahn, Göran Salerud and Tomas Strömberg, Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting, Journal of Biomedical Optics, (13), 5, 054030, 2008. http://dx.doi.org/10.1117/1.2976433 Copyright 2008 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

    Available from: 2009-01-12 Created: 2009-01-09 Last updated: 2017-05-23Bibliographically approved
    4. Visible, Hyperspectral Imaging Evaluating the Cutaneous Response to Ultraviolet Radiation
    Open this publication in new window or tab >>Visible, Hyperspectral Imaging Evaluating the Cutaneous Response to Ultraviolet Radiation
    2007 (English)In: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V / [ed] Daniel L. Farkas; Robert C. Leif; Dan V. Nicolau, SPIE - International Society for Optical Engineering, 2007, p. 644103-1-644103-12Conference paper, Published paper (Other academic)
    Abstract [en]

    In vivo diagnostics of skin diseases as well as understanding of the skin biology constitute a field demanding characterization of physiological and anatomical parameters. Biomedical optics has been successfully used, to qualitatively and quantitatively estimate the microcirculatory conditions of superficial skin. Capillaroscopy, laser Doppler techniques and spectroscopy, all elucidate different aspects of microcirculation, e.g. capillary anatomy and distribution, tissue perfusion and hemoglobin oxygenation. We demonstrate the use of a diffuse reflectance hyperspectral imaging system for spatial and temporal characterization of tissue oxygenation, important to skin viability. The system comprises: light source, liquid crystal tunable filter, camera objective, CCD camera, and the decomposition of the spectral signature into relative amounts of oxy- and deoxygenized hemoglobin as well as melanin in every pixel resulting in tissue chromophore images. To validate the system, we used a phototesting model, creating a graded inflammatory response of a known geometry, in order to evaluate the ability to register spatially resolved reflectance spectra. The obtained results demonstrate the possibility to describe the UV inflammatory response by calculating the change in tissue oxygen level, intimately connected to a tissue's metabolism. Preliminary results on the estimation of melanin content are also presented.

    Place, publisher, year, edition, pages
    SPIE - International Society for Optical Engineering, 2007
    Series
    Proceedings of SPIE (Progress in biomedical optics and imaging), ISSN 1605-7422 ; 6441
    Keywords
    Hyperspectral imaging, Ultraviolet provocation, Erythema, Hemoglobin, CCD camera, Tunable filters
    National Category
    Medical Laboratory and Measurements Technologies
    Identifiers
    urn:nbn:se:liu:diva-15190 (URN)10.1117/12.698165 (DOI)000245855200002 ()9780819465542 (ISBN)
    Conference
    Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V, 20 January 2007, San Jose, CA, USA
    Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2014-01-30Bibliographically approved
  • 176.
    Häggblad, Erik
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Arildsson, Mikael
    Linköping University, Department of Biomedical Engineering.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Reflection Spectroscopy of Analgesized Skin2001In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 62, no 3, p. 392-400 Article in journal (Refereed)
    Abstract [en]

    Analgesized skin, when subjected to heat stimuli, responds by increasing skin perfusion. This response does not originate from increased perfusion in superficial capillaries, but rather in the deeper lying vessels. The aim of this study was to assess changes in blood chromophore content, measured by reflection spectroscopy, in relation to the perfusion increase, especially regarding the chromophores oxyhemoglobin and deoxyhemoglobin. Eleven normal subjects were treated with analgesic cream (EMLA) and placebo for 20, 40, 60, 120, and 180 min. Individual reactions to local heating were classified as responses if the change in reflection data or the change in perfusion, as measured by laser Doppler blood flowmetry, exceeded 2 standard deviations of normal variation. The increase in blood perfusion or in blood content gave rise to an increased absorption, interpreted as an increase due mainly to the chromophore oxyhemoglobin. The number of responses increased with increased treatment time for EMLA-treated areas. In general, there was a good agreement between both methods; 44 of 55 classifications coincided for the two methods used. In conclusion, analgesized forearm skin, which had been exposed to local heating, responded with an elevated perfusion consisting of oxygenated blood. This strengthens the hypothesis that the flow increase occurs through dilatation of larger deeper lying skin vessels and not in the capillaries.

  • 177.
    Häggblad, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Larsson, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Arildsson, Mikael
    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.
    Reflektionsspektroskopi på EML-behandlad och värmeprovocerad hud2000In: Svenska läkarsällskapets Riksstämma,2000, 2000, p. 250-250Conference paper (Other academic)
  • 178.
    Häggblad, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Larsson, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Arildsson, Mikael
    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.
    Reflectance spectroscopy of analgesized skin after local healing2000In: CNVD,2000, 2000Conference paper (Refereed)
  • 179.
    Häggblad, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Larsson, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Arildsson, Mikael
    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.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Reflectance spectroscopy2000In: Eight Int Symp CNVD 2000,2000, 2000, p. 45-50Conference paper (Other academic)
  • 180.
    Häggblad, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Lindbergh, Tobias
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Karlsson, M. G. Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Casimir-Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    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.
    Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting2008In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 13, no 5, p. 054030-Article in journal (Refereed)
    Abstract [en]

    We present a study using a method able to assess tissue oxygenation, taking into account the absorption and the level of scattering in myocardial tissue using a calibrated fiber optic probe. With this method, interindividual comparisons of oxygenation can be made despite varying tissue optical properties during coronary artery bypass grafting (CABG). During CABG, there are needs for methods allowing continuous monitoring and prediction of the metabolism in the myocardial tissue. 14 patients undergoing CABG are investigated for tissue oxygenation during different surgical phases using a handheld fiber optic spectroscopic probe with a source-detector distance of less than 1 mm. The probe is calibrated using a light transport model, relating the absorption and reduced scattering coefficients (mu(a) and mu()(s)) to the measured spectra. By solving the inverse problem, absolute measures of tissue oxygenation are evaluated by the sum of oxygenized hemoglobin and myoglobin. Agreement between the model and measurements is obtained with an average correlation coefficient R-2 of 0.96. Oxygenation is found to be significantly elevated after aorta cross-clamping and cardioplegic infusion, as well as after reperfusion, compared to a baseline (p < 0.05). Tissue oxygenation decreases during cardiac arrest and increases after reperfusion.

  • 181.
    Häggblad, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Lindbergh, Tobias
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Larsson, Marcus
    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.
    Myocardial blood volume and oxygenation monitoring during thoracic surgery2005Conference paper (Other academic)
  • 182.
    Häggblad, Erik
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Petersson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ilias, Michail A.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson, Chris D
    Linköping University, Department of Clinical and Experimental Medicine, Dermatology and Venerology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Dermatology and Venerology in Östergötland.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A diffuse reflectance spectroscopic study of UV-induced erythematous reaction across well-defined borders in human skin2010In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 16, no 3, p. 283-290Article in journal (Refereed)
    Abstract [en]

    Introduction The colour of tissue is often of clinicaluse in the diagnosis of tissue homeostasis andphysiological responses to various stimuli.Determining tissue colour changes and borders,however, often poses an intricate problem and visualexamination, constituting clinical praxis, does notallow them to be objectively characterized orquantified. Demands for increased inter- and intraobserverreproducibility have been incentives for theintroduction of objective methods and techniques fortissue colour (e.g. erythema) evaluation. The aim ofthe present paper was to study the border zone of anUVB provoked erythematous response of humanskin in terms of blood volume and oxygenationmeasured by means of diffuse reflectancespectroscopy using a commercial probe.

    Material and Methods A provocation model, basedon partial masking of irradiated skin areas, definestwo erythema edges at every skin site responding tothe UV irradiation. In every subject, 5 test sites wereexposed with a constant UV light irradiance (14mW/cm2), but with different exposures times (0, 3,6, 9, 12 seconds). An analysis of the spectral datameasured across the two edges was performed for every scan line. The oxygenized and deoxygenizedhemoglobin contents were estimated in everymeasurement point, using a modified Beer-Lambertmodel.

    Results The fit of the experimental data to the model derived by the modified Beer-Lambert law was excellent (R2>0.95). Analyzing data for the chromophore content showed that the erythematous response in provoked areas is dominated by the increase in oxyhemoglobin. The width for the left and right border zone was estimated to 1.81±0.93 mm and 1.90±0.88 mm respectively (M±SD). The unprovoked area between the two edges was estimated to 0.77±0.68 mm.

    Conclusion While the chosen data analysis performed satisfactory, the ability of the probe design to differentiate spatial aspects of a reaction with abrupt borders was found to be suboptimal resulting in a probable overestimation of the erythematous edge slope. Probe modification or imaging are possible solutions.

  • 183.
    Häggblad, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Petersson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology.
    Ilias, Michail
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Anderson, Chris
    Linköping University, Department of Biomedicine and Surgery.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    A spectroscopic study of the borders of UV-induced skin erythema2003In: International Congress for Bioengineering and the Skin. Congress of the International Society for Skin Imaging,2003, 2003, p. 180-181Conference paper (Other academic)
  • 184.
    Hård af Segerstad, Helene
    et al.
    Linköping University, Department of Behavioural Sciences and Learning. Linköping University, Faculty of Educational Sciences.
    Setterud, Helen
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Arts and Sciences.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    An alternative supervision model of Master thesis2008Conference paper (Other academic)
  • 185.
    Hård af Segerstad, Helene
    et al.
    Linköping University, Department of Behavioural Sciences and Learning. Linköping University, Faculty of Educational Sciences.
    Setterud, Helen
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Arts and Sciences.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Master students and supervisors’ conceptions and experiences of an alternative model of supervision2008Conference paper (Other academic)
  • 186.
    Hübbert, Laila
    et al.
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Cardiology in Linköping.
    Peterzén, Bengt
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Ahn, Henrik
    Linköping University, Department of Medical and Health Sciences, Thoracic Surgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Janerot Sjöberg, Birgitta
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Second Harmonic Echocardiography and Spontaneous Contrast during Implantation of a left Ventricular Assist Device2010In: ASAIO journal (1992), ISSN 1058-2916, E-ISSN 1538-943X, Vol. 56, no 5, p. 417-421Article in journal (Refereed)
    Abstract [en]

    Implantable mechanical left ventricular assist devices (LVADs) are used as a bridge or alternative to heart transplantation. Peroperative transesophageal echocardiography is commonly applied during implantation. Significant air embolism may occur as a result of air leakage at connections and anastomoses when LV filling becomes inadequate, and this must be prevented. Early suspicion and detection of air is mandatory to avoid negative circulatory effects. We hypothesized that monitoring of heart chamber size and occurrence of single air bubbles using second harmonic imaging (SHI) echocardiography may prevent risk for significant air embolism. After implantation of the LVAD in 10 calves, invasive hemodynamic monitoring and epicardial SHI were performed while increasing pump speed. Air bubbles in the ascending aorta were monitored and the left heart visualized for off-line dimensional analysis. Detection of air bubbles in the ascending aorta preceded their appearance in the left ventricle. They occurred exclusively but not always after a decrease in left atrial (LA) size. Decrease in LA pressure did not predict bubble detection or reduction in LA size. We conclude that SHI detects spontaneous ultrasound contrast during implantation of a LVAD and that a decrease in LA size is a warning that air embolism is imminent.

  • 187.
    Hübbert, Laila
    et al.
    Linköping University, Department of Medicine and Health Sciences, Cardiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Cardiology UHL.
    Peterzén, Bengt
    Linköping University, Department of Medicine and Health Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Thoracic and Vascular Surgery in Östergötland.
    Ahn, Henrik
    Linköping University, Department of Medicine 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.
    Lönn, Urban
    Linköping University, Department of Medicine and Health Sciences. Linköping University, Faculty of Health Sciences.
    Janerot-Sjöberg, Birgitta
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Echocardiography and myocardial Doppler indices in the anesthetized calf: A closed and open chest studyManuscript (preprint) (Other academic)
    Abstract [en]

    Aim: the aim of this study was to provide baseline central hemodynamic and echocardiographic values in an anaesthetized calf model before and after sternotomy, and to include tissue Doppler imaging (TDI) modalities so that they may be applied to future anaesthetized calf models in cardiovascular research.

    Method and results: twenty-one healthy anaesthetized calves were catheterized and invasively and echocardiographic monitored before and after sternotomy using a pulmonary artery catheter, left atrial and carotid artery catheters, and transthoracic or pericardial echocardiography. The following data were registered: heart rate, mean arterial pulmonary and systemic pressures, central venous pressure and saturation, cardiac output, left and right ventricular dimensions and their myocardial regional basal peak velocity and strain rate during systole, early diastolic and atrial filling and systolic peak strain and systolic displacement.

    After sternotomy, the heart rate, systemic arterial pressure and left ventricular size increased, but other cardiovascular parameters, including echocardiographic myocardial velocities, strain and displacement did not change.

    Conclusion: transthoracic and pericardial echocardiography including TDI, is feasible and applicable to the anaesthetized calf model. The normal ranges for baseline hemodynamic and echocardiographic variables derived from this study demonstrate that, as in humans, sternotomy influences basic hemodynamic variables such as heart rate, blood pressure and heart volumes but does not significantly affect TDI. The data collected may be useful in the future development of cardiovascular research using the anaesthetized calf model.

  • 188.
    Ilias, Michail
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Skin phototesting using a divergent ultraviolet B beam: development and evaluation on a normal material1999Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The phototesting method proposed provokes the skin by means of a divergent UVB beam. The beam divergence is induced by an optical plano-concave !ens placed at the opening of the light guide which directs the light from the UV lamp to the skin. The relationship between the dose administration and the following skin response could be fully exploited by the introduction of adapted dosimetry and skin assessment techniques and procedures. Two-dimensional maps of the irradiance field were plotted by use of a specially built scanning detector unit. The beam divergence thus resulted in an irradiance (dose) field with a profile consisting of 20 sampled irradiance (dose) values, administered to the skin <luring one single illumination. Skin reaction diameter was measured both visually and by laser Doppler perfusion imaging (LDPI). This diameter was then directly translated to an MED value by utilisation of the mm for mm correspondence between skin response and irradiance field.

    Phototesting based on the divergent UVB beam was evaluated on 20 healthy volunteers. The method proved its potential to determine an MED with a single provocation. No systematic difference could be seen between assessment methods (LDPI and visual assessment). The 95% confidence interval for the mean difference between LDPI and visual diameters was calculated to (-0.8, 2.0). Exploiting the characteristic symmetry in both LDPI and dosimetry data allowed the generation of dose-response information for each subject.

    The divergent beam phototesting protocol has shown sufficient promise to warrant further improvement of the technical pre-requisites, the extension of the clinical material to patients with known light sensitivity and the investigation of the technique' s use in basic research.

  • 189.
    Ilias, Michail A.
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Häggblad, Erik
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson, Chris
    Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology UHL.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Visible, Hyperspectral Imaging Evaluating the Cutaneous Response to Ultraviolet Radiation2007In: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V / [ed] Daniel L. Farkas; Robert C. Leif; Dan V. Nicolau, SPIE - International Society for Optical Engineering, 2007, p. 644103-1-644103-12Conference paper (Other academic)
    Abstract [en]

    In vivo diagnostics of skin diseases as well as understanding of the skin biology constitute a field demanding characterization of physiological and anatomical parameters. Biomedical optics has been successfully used, to qualitatively and quantitatively estimate the microcirculatory conditions of superficial skin. Capillaroscopy, laser Doppler techniques and spectroscopy, all elucidate different aspects of microcirculation, e.g. capillary anatomy and distribution, tissue perfusion and hemoglobin oxygenation. We demonstrate the use of a diffuse reflectance hyperspectral imaging system for spatial and temporal characterization of tissue oxygenation, important to skin viability. The system comprises: light source, liquid crystal tunable filter, camera objective, CCD camera, and the decomposition of the spectral signature into relative amounts of oxy- and deoxygenized hemoglobin as well as melanin in every pixel resulting in tissue chromophore images. To validate the system, we used a phototesting model, creating a graded inflammatory response of a known geometry, in order to evaluate the ability to register spatially resolved reflectance spectra. The obtained results demonstrate the possibility to describe the UV inflammatory response by calculating the change in tissue oxygen level, intimately connected to a tissue's metabolism. Preliminary results on the estimation of melanin content are also presented.

  • 190.
    Ilias, Michail
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Falk, M.
    Andersson, Chris
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Quantitative phototesting on the human skin2003In: CNVD,2003, 2003Conference paper (Other academic)
  • 191.
    Ilias, Michail
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Westermark, Frida
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Brantmark, Martin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Andersson-Engels, Stefan
    Department of Physics, Lund Institute of Technology, Lund, Sweden.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Evaluation of a Fiber-Optic Fluorescence Spectroscopy System to Assist Neurosurgical Tumor Resections2007In: Novel Optical Instrumentation for Biomedical Applications III (Proceedings Volume) / [ed] Christian D. Depeursinge, Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2007, Vol. 6631, p. 66310W-1-66310W-8Conference paper (Other academic)
    Abstract [en]

    The highly malignant brain tumor, glioblastoma multiforme, is difficult to totally resect without aid due to its infiltrative way of growing and its morphological similarities to surrounding functioning brain under direct vision in the operating field. The need for an inexpensive and robust real-time visualizing system for resection guiding in neurosurgery has been formulated by research groups all over the world. The main goal is to develop a system that helps the neurosurgeon to make decisions during the surgical procedure. A compact fiber optic system using fluorescence spectroscopy has been developed for guiding neurosurgical resections. The system is based on a high power light emitting diode at 395 nm and a spectrometer. A fiber bundle arrangement is used to guide the excitation light and fluorescence light between the instrument and the tissue target. The system is controlled through a computer interface and software package especially developed for the application. This robust and simple instrument has been evaluated in vivo both on healthy skin but also during a neurosurgical resection procedure. Before surgery the patient received orally a low dose of 5-aminolevulinic acid, converted to the fluorescence tumor marker protoporphyrin IX in the malignant cells. Preliminary results indicate that PpIX fluorescence and brain tissue autofluorescence can be recorded with the help of the developed system intraoperatively during resection of glioblastoma multiforme.

  • 192.
    Ilias, Michail
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Richter, Johan
    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.
    Andersson-Engels, Stefan
    Inst för fysik Lunds tekniska högskola.
    Ett optiskt instrument för intraoperativ registrering av fluorescensspektra vid resektion av hjärntumörer - Ett framtida beslutsstödssystem för kirurgen?2007In: Medicinteknikdagarna,2007, 2007Conference paper (Other academic)
  • 193.
    Ilias, Michail
    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.
    Stücker, M.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Karaktärisering av blodperfusionen i hudtumörer2002In: VINNOVA medicinteknisk konferens,2002, 2002Conference paper (Other academic)
  • 194.
    Ilias, Michail
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Evaluation of a new phototesting method1997In: Congress of the International Society for skin Imaging,1997, 1997Conference paper (Refereed)
  • 195.
    Ilias, Michail
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Stücker, M.
    Describing skin tumors in terms of perfusion estimates2001In: 7th Wold Congress on Microcirculation,2001, 2001Conference paper (Other academic)
  • 196.
    Johansson, Anders
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Strömberg, Tomas
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Influence of tidal volume and thoraco-abdominal separation on the respiratory induced variation of the photoplethysmogram2000In: Journal of clinical monitoring and computing, ISSN 1387-1307, E-ISSN 1573-2614, Vol. 16, no 8, p. 575-581Article in journal (Refereed)
    Abstract [en]

    Objective. The present study was aimed at determining the relative influences of tidal volume and thoraco-abdominal separation (relative thoracic and abdominal contribution to the tidal volume) on the respiratory induced intensity variation (RIIV) of the photoplethysmographic signal. The effects were studied in two body positions. Methods. Respiratory inductive plethysmography was used or quantifying thoraco-abdominal separation and for assessing tidal volumes. 10 subjects were trained to perform widely varying degrees of thoraco-abdominal separation at different tidal volumes. The relationship between the RIIV signal peak-to-peak value (measured at the forearm), and the tidal volume and thoraco-abdominal separation was investigated in two body positions with the use of multiple linear regression. Results. Larger tidal volume and more thoracic contribution to respiration were found to increase the RIIV peak-to-peak value (p < 0.0005). In the supine position, the tidal volume influence was stronger than that of thoraco-abdominal separation, and in the sitting position, the opposite was seen. Conclusions. The effects on the RIIV signal following changes in thoraco-abdominal separation and tidal volume are of the same order of magnitude. In the supine position, the influence of thoracic versus abdominal contribution to the tidal volume is not as significant as in the sitting position. Photoplethysmography is a promising technique for combined monitoring of several respiratory parameters, including tidal volume. In situations where the relative thoracic and abdominal contribution are likely to vary, the tidal volume information becomes less reliable.

  • 197.
    Johansson, Anders
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Öberg, Åke
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Sundqvist, Tommy
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology.
    Sundberg, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Assessment of cartilage thickness utilising reflectance spectroscopy2002In: Nordic Baltic Conference on Biomedical Engineering,2002, 2002Conference paper (Refereed)
    Abstract [en]

      

  • 198.
    Johansson, Johannes
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Impact of Tissue Characteristics on Radio-Frequency Lesioning and Navigation in the Brain: Simulation, experimental and clinical studies2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Radio-Frequency (RF) lesioning, or RF ablation, is a method that uses high frequency currents for thermal coagulation of pathological tissue or signal pathways. The current is delivered from an electrode, which also contains a temperature sensor permitting control of the current at a desired target temperature. In the brain, RF lesioning can e.g. be used for treatment of severe chronic pain and movement disorders such as Parkinson’s disease. This thesis focuses on modelling and simulation with the aim of gaining better understanding and predictability of the lesioning process in the central brain.

     

    The finite element method (FEM), together with experimental comparisons, was used to study the effects of electric and thermal conductivity, blood perfusion (Paper I), and cerebrospinal fluid (CSF) filled cysts (Paper II) on resulting lesion volume and shape in brain tissue. The influence of blood perfusion was modelled as an increase in thermal conductivity in non-coagulated tissue. This model gave smaller simulated lesions with increasing blood perfusion as heat was more efficiently conducted from the rim of the lesion. If the coagulation was not taken into consideration, the lesion became larger with increasing thermal conductivity instead, as the increase in conducted heat was compensated for through an increased power output in order to maintain the target temperature. Simulated lesions corresponded well to experimental in-vivo lesions. The electric conductivity in a homogeneous surrounding had little impact but this was not true for a heterogeneous surrounding. CSF has a much higher electric conductivity than brain tissue, which focused the current to the cyst if the electrode tip was in contact with both a cyst and brain tissue. Heating of CSF could also cause considerable convective flow and as a result a very efficient heat transfer. This affected both simulated and experimental lesion sizes and shapes. As a result both very large and very small lesions could be obtained depending on whether sufficient power was supplied or if the heating was mitigated over a large volume.

     

    Clinical (Paper IV) and experimental (Paper III) measurements were used for investigation of changes in reflected light intensity from undamaged and coagulating brain tissue respectively. Monte Carlo (MC) simulations for light transport were made for comparison (Paper V). For the optical measurements, an RF electrode with adjacent optical fibres was used and this electrode was also modelled for the optical simulations. According to the MC simulations, coagulation should make grey matter lighter and white matter darker, while thalamic light grey should remain approximately the same. Experiments in ex-vivo porcine tissue gave an increase in reflected light intensity from grey matter at approximately 50 °C but the signal was very variable and the isotherm 60 °C gave better agreement between simulated and experimental lesions. No consistent decrease in reflected light intensity could be seen during coagulation of white matter. Clinical measurements were performed during the creation of 21 trajectories for deep brain stimulation electrodes. In agreement with the simulations, reflected light intensity was found to differentiate well between undamaged grey, light grey and white matter.

     

    In conclusion, blood perfusion and CSF in particular may greatly affect the lesioning process and can be important to consider when planning surgery. Reflected light intensity seems unreliable for the detection of coagulation in light grey brain matter such as the thalamus. However, it seems very promising for navigation in the brain and for detection of coagulation in other tissue types such as muscle.

    List of papers
    1. Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction
    Open this publication in new window or tab >>Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction
    Show others...
    2006 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, no 9, p. 757-766Article in journal (Refereed) Published
    Abstract [en]

    Radio-frequency brain lesioning is a method for reducing e.g. symptoms of movement disorders. A small electrode is used to thermally coagulate malfunctioning tissue. Influence on lesion size from thermal and electric conductivity of the tissue, microvascular perfusion and preset electrode temperature was investigated using a finite-element model. Perfusion was modelled as an increased thermal conductivity in non-coagulated tissue. The parameters were analysed using a 24-factorial design (n = 16) and quadratic regression analysis (n = 47). Increased thermal conductivity of the tissue increased lesion volume, while increased perfusion decreased it since coagulation creates a thermally insulating layer due to the cessation of blood perfusion. These effects were strengthened with increased preset temperature. The electric conductivity had negligible effect. Simulations were found realistic compared to in vivo experimental lesions.

    Place, publisher, year, edition, pages
    Heidleberg: Springer, 2006
    Keywords
    Electrosurgery, RF ablation, Brain, Blood perfusion, Finite-element method
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-15926 (URN)10.1007/s11517-006-0098-1 (DOI)000240378700003 ()16941099 (PubMedID)2-s2.0-33748485613 (Scopus ID)
    Note

    The original publication is available at www.springerlink.com: Johannes D Johansson, Ola Eriksson, Joakim Wren, Dan Loyd and Karin Wårdell, Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction, 2006, Medical and Biological Engineering and Computing, (44), 9, 757-766. http://dx.doi.org/10.1007/s11517-006-0098-1 Copyright: Springer Science Business Media http://www.springerlink.com/

    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-12-14Bibliographically approved
    2. Impact of cysts during radio frequency (RF) lesioning in deep brain structures: a simulation and in-vitro study
    Open this publication in new window or tab >>Impact of cysts during radio frequency (RF) lesioning in deep brain structures: a simulation and in-vitro study
    2007 (English)In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 4, no 2, p. 87-95Article in journal (Refereed) Published
    Abstract [en]

    Radiofrequency lesioning of nuclei in the thalamus or the basal ganglia can be used to reduce symptoms caused by e.g. movement disorders such as Parkinson's disease. Enlarged cavities containing cerebrospinal fluid (CSF) are commonly present in the basal ganglia and tend to increase in size and number with age. Since the cavities have different electrical and thermal properties compared with brain tissue, it is likely that they can affect the lesioning process and thereby the treatment outcome. Computer simulations using the finite element method and in vitro experiments have been used to investigate the impact of cysts on lesions' size and shape. Simulations of the electric current and temperature distributions as well as convective movements have been conducted for various sizes, shapes and locations of the cysts as well as different target temperatures. Circulation of the CSF caused by the heating was found to spread heat effectively and the higher electric conductivity of the CSF increased heating of the cyst. These two effects were together able to greatly alter the resulting lesion size and shape when the cyst was in contact with the electrode tip. Similar results were obtained for the experiments.

    Place, publisher, year, edition, pages
    Institute of Physics Publishing (IOPP), 2007
    Keywords
    Electrosurgery, RF ablation, Brain, Blood perfusion, Finite-element method
    National Category
    Other Medical Engineering
    Identifiers
    urn:nbn:se:liu:diva-13997 (URN)10.1088/1741-2560/4/2/009 (DOI)000247947300015 ()17409483 (PubMedID)2-s2.0-34247183212 (Scopus ID)
    Note

    Original Publication: Johannes D. Johansson, Dan Loyd, Karin Wårdell and Joakim Wren, Impact of cysts during radio frequency (RF) lesioning in deep brain structures: a simulation and in-vitro study, 2006, Journal of Neural Ingeneering, (4), 2, 87-95. http://dx.doi.org/10.1088/1741-2560/4/2/009 Copyright: Institute of Physics Publishing http://www.iop.org/

    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-12-13Bibliographically approved
    3. Diffuse Reflectance Spectroscopy During Experimental Radio Frequency Ablation
    Open this publication in new window or tab >>Diffuse Reflectance Spectroscopy During Experimental Radio Frequency Ablation
    2008 (English)In: 14th Nordic-Baltic Conference on Biomedical Engineering and Medical Physics: NBC 2008 16–20 June 2008 Riga, Latvia / [ed] Alexei Katashev, Yuri Dekhtyar, Janis Spigulis, Heidelberg: Springer Berlin/Heidelberg, 2008, p. 371-374Chapter in book (Refereed)
    Abstract [en]

    The aim of the study was to investigate the spectral changes during heating and to estimate threshold temperatures for initiation of the thermal coagulation. A brain electrode with optical fibers was used to generate lesions in ex-vivo porcine white and gray matter as well as in fat and meat from pork chop. Radio frequency ablation (60 s, 48–90 °C, steps of 2-10 °C) was performed while simultaneous spectroscopy measurements were made in the range 490–900 nm.

    The optical signal recorded from porcine gray and white brain matter was unstable with the reflected light intensity fluctuating a lot. Nevertheless an abrupt increase in light intensity during coagulation in gray matter was found at 48 ± 6 °C (n = 21), probably indicating onset of coagulation. The reflected light intensity from white matter showed no consistent behavior during coagulation.

    The results for pork chop meat and fat were considerably more consistent. The reflected light intensity from pork chop meat stayed stable up to a mean temperature of 42.5 ± 3.5 °C (n = 11). Above this temperature it abruptly increased for all wavelengths. The reflected light intensity from pork chop fat dropped over all wavelengths immediately as the temperature increased and remained low as the fat cooled (n = 8).

    In conclusion diffuse reflectance spectroscopy appears to be suitable to detect onset of coagulation in muscle tissue and gray matter. The estimated initiation temperature of coagulation varied and was dependent on tissue type.

    Place, publisher, year, edition, pages
    Heidelberg: Springer Berlin/Heidelberg, 2008
    Series
    IFMBE Proceedings, ISSN 1680-0737 ; 20
    Keywords
    Radio frequency ablation, diffuse reflectance spectroscopy, brain, muscle, fat
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-15927 (URN)10.1007/978-3-540-69367-3_99 (DOI)978-3-540-69366-6 (ISBN)978-3-540-69367-3 (ISBN)
    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-02-16Bibliographically approved
    4. Combined diffuse light reflectance and electric impedance measurements for navigation aid in deep brain surgery
    Open this publication in new window or tab >>Combined diffuse light reflectance and electric impedance measurements for navigation aid in deep brain surgery
    Show others...
    2009 (English)In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 87, no 2, p. 105-113Article in journal (Refereed) Published
    Abstract [en]

    Aim: The aim of this study is to investigate reflected light intensity combined with impedance for navigation aid during stereotactic neurosurgery.

    Methods: During creation of 21 trajectories for stereotactic implantation of deep brain stimulation electrodes in the globus pallidus internus or subthalamus (zona incerta or subthalamic nucleus), impedance at 512 kHz and reflected light intensity at 780 nm were measured continuously and simultaneously with a radio frequency electrode containing optical fibres. The signals were compared with anatomy determined from pre- and postoperative MRI and CT. The measurements were performed within minutes and signal analysis was done post-operatively.

    Results: Reflected light intensity was low from cortex, lateral ventricle, caudate nucleus and putamen. It was intermediate from globus pallidus and thalamus while it was high from subcortical white matter, internal capsule and the subthalamus. The electric impedance was less consistent but generally low in the cortex, intermediate in subcortical white matter, the putamen, the globus pallidus and the thalamus and high in the internal capsule and the subthalamus.

    Conclusion: Reflected light intensity and electric impedance give complementary information about passed tissue and the combination seems promising for navigation aid during stereotactic neurosurgery.

    Keywords
    Stereotactic surgery, navigation, electric impedance, light reflectance
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-15929 (URN)10.1159/000202977 (DOI)
    Note

    Original Publication: Johannes D. Johansson, Patric Blomstedt, Neda Haj-Hosseini, Tommy Bergenheim, Ola Eriksson and Karin Wårdell, Combined diffuse light reflectance and electric impedance measurements for navigation aid in deep brain surgery, 2009, Stereotactic and Functional Neurosurgery, (87), 2, 105-113. http://dx.doi.org/10.1159/000202977 Copyright: S. Karger AG http://www.karger.com/

    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-12-14Bibliographically approved
    5. Simulation of reflected light intensity changes during navigation and radio frequency lesioning in the brain
    Open this publication in new window or tab >>Simulation of reflected light intensity changes during navigation and radio frequency lesioning in the brain
    2009 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 14, no 044040Article in journal (Refereed) Published
    Abstract [en]

    An electrode with adjacent optical fibers for measurements during navigation and radio frequency lesioning in the brain was modeled for Monte Carlo simulations of light transport in brain tissue. Relative reflected light intensity at 780 nm, I780, from this electrode and probes with identical fiber configuration were simulated using the intensity from native white matter as reference. Models were made of homogeneousnative and coagulated gray, thalamus, and white matter as well as blood. Dual layermodels, including models with a layer of cerebrospinal fluid between the fibers andthe brain tissue, were also made. Simulated I780 was 0.16 for gray matter, 0.67 forcoagulate gray matter, 0.36 for thalamus, 0.39 for coagulated thalamus, unity forwhite matter, 0.70 for coagulated white matter and 0.24 for blood. Thalamic matterhas also been found to reflect more light than gray matter and less than white matterin clinical studies. In conclusion the reflected light intensity can be used todifferentiate between gray and white matter during navigation. Furthermore,coagulation of light gray tissue, such as the thalamus, might be difficult to detectusing I780, but coagulation in darker gray tissue should result in a rapid increase of I780.

    Place, publisher, year, edition, pages
    SPIE - International Society for Optical Engineering, 2009
    Keywords
    Brain, Monte Carlo simulations, diffuse reflectance, navigation, radio-frequency lesioning
    National Category
    Bioengineering Equipment
    Identifiers
    urn:nbn:se:liu:diva-15930 (URN)10.1117/1.3210781 (DOI)000270540100046 ()19725751 (PubMedID)2-s2.0-73349106860 (Scopus ID)
    Note

    Original Publication: Johannes D. Johansson, Ingemar Fredriksson, Karin Wårdell and Ola Eriksson, Simulation of reflected light intensity changes during navigation and radio frequency lesioning in the brain, Journal of Biomedical Optics, (14), 044040, (2009). http://dx.doi.org/10.1117/1.3210781 Copyright 2009 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-12-14Bibliographically approved
  • 199.
    Johansson, Johannes
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Spectroscopic method for determination of the absorption coefficient in brain tissue2010In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 15, no 5, p. 057005-1-057005-9Article in journal (Refereed)
    Abstract [en]

    I use MonteCarlo simulations and phantom measurements to characterize a probe withadjacent optical fibres for diffuse reflectance spectroscopy during stereotactic surgeryin the brain. Simulations and measurements have been fitted toa modified Beer–Lambert model for light transport in order tobe able to quantify chromophore content based on clinically measuredspectra in brain tissue. It was found that it isimportant to take the impact of the light absorption intoaccount when calculating the apparent optical path length, lp, forthe photons in order to get good estimates of theabsorption coefficient, µa. The optical path length was found tobe well fitted to the equation lp=a+b ln(Is)+c ln(µa)+d ln(Is)ln(µa), where Is isthe reflected light intensity for scattering alone (i.e., zero absorption).Although coefficients ad calculated in this study are specific tothe probe used here, the general form of the equationshould be applicable to similar probes.

  • 200.
    Johansson, Johannes
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Thermocoagulation in Deep Brain Structures: Modelling, simulation and experimental study of radio-frequency lesioning2006Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Radio-frequency (RF) lesioning is a method utilising high frequency currents for thermal coagulation of pathological tissue or signal pathways. The current is delivered from an electrode with a temperature sensor, permitting control of the current at a desired target temperature. In the brain RF-lesioning can e.g. be used for severe chronic pain and movement disorders such as Parkinson’s disease. This thesis focuses on modelling and simulation with the aim of gaining better understanding and predictability of the lesioning process in deep brain structures. The finite element method (FEM) together with experimental comparisons was used to study the effects of electrode dimensions, electrode target temperature, electric and thermal conductivity of the brain tissue, blood perfusion and cerebrospinal fluid (CSF) filled cysts. Equations for steady current, thermal transport and incompressible flow were used together with statistical factorial design and regression analysis for this purpose.

    Increased target temperature, electrode tip length and electrode diameter increased the simulated lesion size, which is in accordance with experimental results. The influence of blood perfusion, modelled as an increase in thermal conductivity in non-coagulated tissue, gave smaller simulated lesions with increasing blood perfusion as heat was more efficiently conducted from the rim of the lesion. If no consideration was taken to the coagulation the lesion became larger with increased thermal conductivity instead, as the increase in conducted heat was compensated for through an increased power output in order to maintain the target temperature. Simulated lesions corresponded well to experimental in-vivo lesions.

    The electric conductivity in a homogeneous surrounding had little impact on lesion development. However this was not valid for a heterogeneous surrounding. CSF-filled cysts have a much higher electric conductivity than brain tissue focussing the current to them if the electrode tip is in contact with both. Heating of CSF can also cause considerable convective flow and as a result a very efficient heat transfer. This affected simulated as well as experimental lesion sizes and shapes resulting in both very large lesions if sufficient power compared to the cysts size was supplied and very small lesions if the power was low, mitigating the heat over a large volume.

    In conclusion especially blood perfusion and CSF can greatly affect the lesioning process and appear to be important to consider when planning surgical procedures. Hopefully this thesis will help improve knowledge about and predictability of clinical lesioning.

    List of papers
    1. Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction
    Open this publication in new window or tab >>Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction
    Show others...
    2006 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, no 9, p. 757-766Article in journal (Refereed) Published
    Abstract [en]

    Radio-frequency brain lesioning is a method for reducing e.g. symptoms of movement disorders. A small electrode is used to thermally coagulate malfunctioning tissue. Influence on lesion size from thermal and electric conductivity of the tissue, microvascular perfusion and preset electrode temperature was investigated using a finite-element model. Perfusion was modelled as an increased thermal conductivity in non-coagulated tissue. The parameters were analysed using a 24-factorial design (n = 16) and quadratic regression analysis (n = 47). Increased thermal conductivity of the tissue increased lesion volume, while increased perfusion decreased it since coagulation creates a thermally insulating layer due to the cessation of blood perfusion. These effects were strengthened with increased preset temperature. The electric conductivity had negligible effect. Simulations were found realistic compared to in vivo experimental lesions.

    Place, publisher, year, edition, pages
    Heidleberg: Springer, 2006
    Keywords
    Electrosurgery, RF ablation, Brain, Blood perfusion, Finite-element method
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-15926 (URN)10.1007/s11517-006-0098-1 (DOI)000240378700003 ()16941099 (PubMedID)2-s2.0-33748485613 (Scopus ID)
    Note

    The original publication is available at www.springerlink.com: Johannes D Johansson, Ola Eriksson, Joakim Wren, Dan Loyd and Karin Wårdell, Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling, simulation and analysis of parameter influence and interaction, 2006, Medical and Biological Engineering and Computing, (44), 9, 757-766. http://dx.doi.org/10.1007/s11517-006-0098-1 Copyright: Springer Science Business Media http://www.springerlink.com/

    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-12-14Bibliographically approved
    2. Comparison between a detailed and a simplified finite element model of radio-frequency lesioning in the brain
    Open this publication in new window or tab >>Comparison between a detailed and a simplified finite element model of radio-frequency lesioning in the brain
    Show others...
    2004 (English)In: 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, San Fransisco, USA, 2004, Vol. 4, p. 2510-2513Conference paper, Published paper (Refereed)
    Abstract [en]

    A detailed and a simplified model of a lesioning electrode was made using the finite element method. 15 simulations of the lesioning procedure were performed for each model and the resulting lesion volumes were compared in order to investigate if the simplified model is adequate. The simplified model resulted in a very slight overestimation of the volume compared to the detailed model. It was thus concluded that the simplified model is adequate for simulations.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13995 (URN)10.1109/IEMBS.2004.1403723 (DOI)
    Available from: 2006-09-25 Created: 2006-09-25 Last updated: 2018-10-08Bibliographically approved
    3. Simulations of radio-frequency lesions with varying brain electrode dimensions
    Open this publication in new window or tab >>Simulations of radio-frequency lesions with varying brain electrode dimensions
    Show others...
    2005 (English)In: 13th Nordic Baltic conference biomedical engineering and medical physics, Umeå, Sweden, 2005, Vol. 9, p. 62-63Conference paper, Published paper (Refereed)
    Abstract [en]

    Radio-frequency (RF) lesioning in the

    brain was simulated using the finite element method

    (FEM). Heating for 60 s with temperature control in

    order to keep the tip at 80 °C was simulated. Length,

    L, (2 – 4 mm) and diameter, D, (0.5 – 2.5 mm) of the

    electrode tip were varied and the resulting lesion

    volumes were used to calculate a regression model:

    Lesion Volume = – 13.1D + 15.7LD + 13.1D2 mm3.

    The results can be useful for electrode design and

    prediction of lesion size.

    Keywords
    Radio-frequency surgery, Brain, Lesion size, Electrode dimensions, Finite Element Method (FEM)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13996 (URN)
    Available from: 2006-09-25 Created: 2006-09-25 Last updated: 2017-02-21Bibliographically approved
    4. Impact of cysts during radio frequency (RF) lesioning in deep brain structures: a simulation and in-vitro study
    Open this publication in new window or tab >>Impact of cysts during radio frequency (RF) lesioning in deep brain structures: a simulation and in-vitro study
    2007 (English)In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 4, no 2, p. 87-95Article in journal (Refereed) Published
    Abstract [en]

    Radiofrequency lesioning of nuclei in the thalamus or the basal ganglia can be used to reduce symptoms caused by e.g. movement disorders such as Parkinson's disease. Enlarged cavities containing cerebrospinal fluid (CSF) are commonly present in the basal ganglia and tend to increase in size and number with age. Since the cavities have different electrical and thermal properties compared with brain tissue, it is likely that they can affect the lesioning process and thereby the treatment outcome. Computer simulations using the finite element method and in vitro experiments have been used to investigate the impact of cysts on lesions' size and shape. Simulations of the electric current and temperature distributions as well as convective movements have been conducted for various sizes, shapes and locations of the cysts as well as different target temperatures. Circulation of the CSF caused by the heating was found to spread heat effectively and the higher electric conductivity of the CSF increased heating of the cyst. These two effects were together able to greatly alter the resulting lesion size and shape when the cyst was in contact with the electrode tip. Similar results were obtained for the experiments.

    Place, publisher, year, edition, pages
    Institute of Physics Publishing (IOPP), 2007
    Keywords
    Electrosurgery, RF ablation, Brain, Blood perfusion, Finite-element method
    National Category
    Other Medical Engineering
    Identifiers
    urn:nbn:se:liu:diva-13997 (URN)10.1088/1741-2560/4/2/009 (DOI)000247947300015 ()17409483 (PubMedID)2-s2.0-34247183212 (Scopus ID)
    Note

    Original Publication: Johannes D. Johansson, Dan Loyd, Karin Wårdell and Joakim Wren, Impact of cysts during radio frequency (RF) lesioning in deep brain structures: a simulation and in-vitro study, 2006, Journal of Neural Ingeneering, (4), 2, 87-95. http://dx.doi.org/10.1088/1741-2560/4/2/009 Copyright: Institute of Physics Publishing http://www.iop.org/

    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-12-13Bibliographically approved
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