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  • 1.
    Alrifaiy, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Luleå University of Technology.
    Bitaraf, Nazanin
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Luleå University of Technology.
    Druzin, Michael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Lindahl, Olof
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Luleå University of Technology.
    Ramser, K
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Luleå University of Technology.
    Hypoxia on a chip: a novel approach for patch-clamp studies in a microfluidic system with full oxygen control2013In: World Congress on Medical Physics and Biomedical Engineering May 26-31, 2012, Beijing, China / [ed] Mian Long, Springer Berlin/Heidelberg, 2013, p. 313-316Conference paper (Refereed)
    Abstract [en]

    A new approach to perform patch-clamp experiments on living cells under controlled anoxic and normoxic conditions was developed and tested. To provide an optimal control over the oxygen content and the biochemical environment a patch-clamp recording micropipette was integrated within an oxygen tight poly-methyl methacrylate (PMMA) based microchip. The oxygen content within the microfluidic chamber surrounding patch-clamp micropipette was maintained at 0.5-1.5 % by a continuous flow of artificial extracellular solution purged with nitrogen. The nerve and glial cells acutely obtained from the male rat brain were trapped by the optical tweezers and steered towards the patch-clamp micropipette through the channels of the microchip in order to achieve a close contact between the pipette and the cellular membrane. The patch-clamp recordings revealed that optical tweezers did not affect the electrophysiological properties of the tested cells suggesting that optical trapping is a safe and non-traumatizing method to manipulate living cells in the microfluidic system. Thus, our approach of combining optical tweezers and a gas-tight microfluidic chamber may be applied in various electrophysiological investigations of single cells were optimal control of the experimental conditions and the sample in a closed environment are necessary.

  • 2.
    Alrifaiy, Ahmed
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Ramser, Kerstin
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    How to integrate a micropipette into a closed microfluidic system: absorption spectra of an optically trapped erythrocyte2011In: Biomedical Optics Express, E-ISSN 2156-7085, Vol. 2, no 8, p. 2299-2306Article in journal (Refereed)
    Abstract [en]

    We present a new concept of integrating a micropipette within a closed microfluidic system equipped with optical tweezers and a UV-Vis spectrometer. A single red blood cell (RBC) was optically trapped and steered in three dimensions towards a micropipette that was integrated in the microfluidic system. Different oxygenation states of the RBC, triggered by altering the oxygen content in the microchannels through a pump system, were optically monitored by a UV-Vis spectrometer. The built setup is aimed to act as a multifunctional system where the biochemical content and the electrophysiological reaction of a single cell can be monitored simultaneously. The system can be used for other applications like single cell sorting, in vitro fertilization or electrophysiological experiments with precise environmental control of the gas-, and chemical content. 

  • 3.
    Ambarki, Khalid
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Lindqvist, Tomas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Petterson, E
    Warntjes, JBM
    Birgander, Richard
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Evaluation of automatic measurement of the intracranial volume based on quantitative MR imaging2012In: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 33, no 10, p. 1951-1956Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND PURPOSE: Brain size is commonly described in relation to ICV, whereby accurate assessment of this quantity is fundamental. Recently, an optimized MR sequence (QRAPMASTER) was developed for simultaneous quantification of T1, T2, and proton density. ICV can be measured automatically within minutes from QRAPMASTER outputs and a dedicated software, SyMRI. Automatic estimations of ICV were evaluated against the manual segmentation.

    MATERIALS AND METHODS: In 19 healthy subjects, manual segmentation of ICV was performed by 2 neuroradiologists (Obs1, Obs2) by using QBrain software and conventional T2-weighted images. The automatic segmentation from the QRAPMASTER output was performed by using SyMRI. Manual corrections of the automatic segmentation were performed (corrected-automatic) by Obs1 and Obs2, who were blinded from each other. Finally, the repeatability of the automatic method was evaluated in 6 additional healthy subjects, each having 6 repeated QRAPMASTER scans. The time required to measure ICV was recorded.

    RESULTS: No significant difference was found between reference and automatic (and corrected-automatic) ICV (P > .25). The mean difference between the reference and automatic measurement was -4.84 ± 19.57 mL (or 0.31 ± 1.35%). Mean differences between the reference and the corrected-automatic measurements were -0.47 ± 17.95 mL (-0.01 ± 1.24%) and -1.26 ± 17.68 mL (-0.06 ± 1.22%) for Obs1 and Obs2, respectively. The repeatability errors of the automatic and the corrected-automatic method were <1%. The automatic method required 1 minute 11 seconds (SD = 12 seconds) of processing. Adding manual corrections required another 1 minute 32 seconds (SD = 38 seconds).

    CONCLUSIONS: Automatic and corrected-automatic quantification of ICV showed good agreement with the reference method. SyMRI software provided a fast and reproducible measure of ICV.

  • 4.
    Ambarki, Khalid
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Petr, J.
    Wahlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Wirestam, R.
    Zarrinkoob, Laleh
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Malm, Jan
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Partial Volume Correction of Cerebral Perfusion Estimates Obtained by Arterial Spin Labeling2015In: 16th Nordic-Baltic Conference on Biomedical Engineering: 16. NBC & 10. MTD 2014 joint conferences. October 14-16, 2014, Gothenburg, Sweden, 2015, Vol. 48, p. 17-19Conference paper (Refereed)
    Abstract [en]

    Arterial Spin labeling (ASL) is a fully non-invasive MRI method capable to quantify cerebral perfusion. However, gray (GM) and white matter (WM) ASL perfusions are difficult to assess separately due to limited spatial resolution increasing the partial volume effects (PVE). In the present study, ASL PVE correction was implemented based on a regression algorithm in 22 healthy young men. PVE corrected perfusion of GM and WM were compared to previous studies. PVE-corrected GM perfusion was in agreement with literature values. In general, WM perfusion was higher despite the use of PVE correction.

  • 5.
    Ambarki, Khalid
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Zarrinkoob, Laleh
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Wirestam, R.
    Petr, J.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Accuracy of Parenchymal Cerebral Blood Flow Measurements Using Pseudocontinuous Arterial Spin-labeling in Healthy Volunteers2015In: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 36, no 10, p. 1816-1821Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND PURPOSE: The arterial spin-labeling method for CBF assessment is widely available, but its accuracy is not fully established. We investigated the accuracy of a whole-brain arterial spin-labeling technique for assessing the mean parenchymal CBF and the effect of aging in healthy volunteers. Phase-contrast MR imaging was used as the reference method. MATERIALS AND METHODS: Ninety-two healthy volunteers were included: 49 young (age range, 20-30 years) and 43 elderly (age range, 65-80 years). Arterial spin-labeling parenchymal CBF values were averaged over the whole brain to quantify the mean pCBF(ASL) value. Total. CBF was assessed with phase-contrast MR imaging as the sum of flows in the internal carotid and vertebral arteries, and subsequent division by brain volume returned the pCBF(PCMRI) value. Accuracy was considered as good as that of the reference method if the systematic difference was less than 5 mL/min/100 g of brain tissue and if the 95% confidence intervals were equal to or better than +/- 10 mL/min/100 g. RESULTS: pCBF(ASL) correlated to pCBF(PCMRI) (r = 0.73; P < .001). Significant differences were observed between the pCBF(ASL) and pCBF(PCMRI) values in the young (P = .001) and the elderly (P < .001) volunteers. The systematic differences (mean 2 standard deviations) were -4 +/- 14 mL/min/100 g in the young subjects and 6 +/- 12 mL/min/100 g in the elderly subjects. Young subjects showed higher values than the elderly subjects for pCBF(PCMRI) (young, 57 +/- 8 mL/min/100 g; elderly, 54 +/- 7 mL/min/100 g; P = .05) and pCBF(ASL) (young, 61 +/- 10 mL/min/100 g; elderly, 48 +/- 10 mL/min/100 g; P < .001). CONCLUSIONS: The limits of agreement were too wide for the arterial spin-labeling method to be considered satisfactorily accurate, whereas the systematic overestimation in the young subjects and underestimation in the elderly subjects were close to acceptable. The age-related decrease in parenchymal CBF was augmented in arterial spin-labeling compared with phase-contrast MR imaging.

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  • 6.
    Andersson, Jonas
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Ryberg, Mats
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Sjöström, Lars-Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wiklund, Urban
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Karpe, Fredrik
    NIHR Oxford Biomedical Research Centre, Churchill Hospital, Oxford, UK..
    Lindahl, Bernt
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Long term effects of a diet intervention on adipose tissue blood flow, heart rate variability and endothelial function: a randomized controlled trialManuscript (preprint) (Other academic)
  • 7.
    Andersson, Kennet
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Manchester, I. R.
    Laurell, Katarina
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Cesarini, K. Giuliana
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Measurement of CSF dynamics with oscillating pressure infusion2013In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 128, no 1, p. 17-23Article in journal (Refereed)
    Abstract [en]

    Introduction Infusion tests are used to diagnose and select patients with idiopathic normal pressure hydrocephalus (INPH) for shunt surgery. The test characterizes cerebrospinal fluid dynamics and estimates parameters of the cerebrospinal fluid system, the pressure-volume index (PVI) and the outflow conductance (Cout). The Oscillating Pressure Infusion (OPI) method was developed to improve the test and reduce the investigation time. The aim of this study was to evaluate the new OPI method by comparing it with an established reference method. Methods Forty-seven patients (age 71.2 +/- 8.9years) with communicating hydrocephalus underwent a preoperative lumbar infusion investigation with two consecutive infusion protocols, reference (42min) and new (20min), that is, 94 infusion tests in total. The OPI method estimated Cout and PVI simultaneously. A real-time analysis of reliability was applied to investigate the possibility of infusion time reduction. Results The difference in Cout between the methods was 1.2 +/- 1.8l/s/kPa (Rout=-0.8 +/- 3.5mmHg/ml/min), P<0.05, n=47. With the reliability analysis, the preset 20min of active infusion could have been even further reduced for 19 patients to between 10 and 19min. PVI was estimated to 16.1 +/- 6.9ml, n=47. Conclusions The novel Oscillating Pressure Infusion method produced real-time estimates of Cout including estimates of reliability that was in good agreement with the reference method and allows for a reduced and individualized investigation time.

  • 8.
    Andersson, Kennet
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Manchester, Ian R
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Eklund, Anders
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Real-time estimation of cerebrospinal fluid system parameters via oscillating pressure infusion2010In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 48, no 11, p. 1123-1131Article in journal (Refereed)
    Abstract [en]

    Hydrocephalus is related to a disturbed cerebrospinal fluid (CSF) system. For diagnosis, lumbar infusion test are performed to estimate outflow conductance, C (out), and pressure volume index, PVI, of the CSF system. Infusion patterns and analysis methods used in current clinical practice are not optimized. Minimizing the investigation time with sufficient accuracy is of major clinical relevance. The aim of this study was to propose and experimentally evaluate a new method, the oscillating pressure infusion (OPI). The non-linear model of the CSF system was transformed into a linear time invariant system. Using an oscillating pressure pattern and linear system identification methods, C (out) and PVI with confidence intervals, were estimated in real-time. Forty-two OPI and constant pressure infusion (CPI) investigations were performed on an experimental CSF system, designed with PVI = 25.5 ml and variable C (out). The ARX model robustly estimated C (out) (mean C (out,OPI) - C (out,CPI) = 0.08 μl/(s kPa), n = 42, P = 0.68). The Box-Jenkins model proved most reliable for PVI (23.7 ± 2.0 ml, n = 42). The OPI method, with its oscillating pressure pattern and new parameter estimation methods, efficiently estimated C (out) and PVI as well as their confidence intervals in real-time. The results from this experimental study show potential for the OPI method and supports further evaluation in a clinical setting.

  • 9.
    Behrens, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Blekinge Centre of Competence, Blekinge Hospital Karlskrona, Karlskrona, Sweden.
    Eklund, Anders
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Elgh, Eva
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Psychiatry.
    Smith, Cynthia
    Williams, Michael A
    Malm, Jan
    A computerized neuropsychological test battery designed for idiopathic normal pressure hydrocephalus2014In: Fluids and Barriers of the CNS, E-ISSN 2045-8118, Vol. 11, article id 22Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: A tool for standardized and repeated neuropsychological assessments in patients with idiopathic normal pressure hydrocephalus (INPH) is needed. The objective of this study was to develop a computerized neuropsychological test battery designed for INPH and to evaluate its reliability, validity and patient's ability to complete the tests.

    METHODS: Based on a structured review of the literature on neuropsychological testing in INPH, the eight tests most sensitive to the INPH cognitive profile were implemented in a computerized format. The Geriatric Depression Scale (GDS) was also included. Tests were presented on a touch-screen monitor, with animated instructions and speaker sound. The battery was evaluated with the following cohorts: A. Test-retest reliability, 44 healthy elderly; B. Validity against standard pen and pencil testing, 28 patients with various cognitive impairments; C. Ability to complete test battery, defined as completion of at least seven of the eight tests, 40 investigated for INPH.

    RESULTS: A. All except the figure copy test showed good test-retest reliability, r = 0.67-0.90; B. A high correlation was seen between conventional and computerized tests (r = 0.66-0.85) except for delayed recognition and figure copy task; C. Seventy-eight percent completed the computerized battery; Patients diagnosed with INPH (n = 26) performed worse on all tests, including depression score, compared to healthy controls.

    CONCLUSIONS: A new computerized neuropsychological test battery designed for patients with communicating hydrocephalus and INPH was introduced. Its reliability, validity for general cognitive impairment and completion rate for INPH was promising. After exclusion of the figure copy task, the battery is ready for clinical evaluation and as a next step we suggest validation for INPH and a comparison before and after shunt surgery.

    TRIAL REGISTRATION: ClinicalTrials.org NCT01265251.

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  • 10.
    Behrens, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Department of Medicine, Blekinge Hospital, Karlskrona.
    Elgh, Eva
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Psychiatry. Umeå University, Faculty of Social Sciences, Department of Psychology.
    Leijon, Göran
    Kristensen, Bo
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    The Computerized General Neuropsychological INPH Test revealed improvement in idiopathic normal pressure hydrocephalus after shunt surgery2020In: Journal of Neurosurgery, ISSN 0022-3085, E-ISSN 1933-0693, Vol. 132, no 3, p. 733-740Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE The Computerized General Neuropsychological INPH Test (CoGNIT) provides the clinician and the researcher with standardized and accessible cognitive assessments in patients with idiopathic normal pressure hydrocephalus (INPH). CoGNIT includes tests of memory, executive functions, attention, manual dexterity, and psychomotor speed. Investigations of the validity and reliability of CoGNIT have been published previously. The aim of this study was to evaluate CoGNIT's sensitivity to cognitive change after shunt surgery in patients with INPH.

    METHODS Forty-one patients with INPH (median Mini-Mental State Examination score 26) were given CoGNIT preoperatively and at a postoperative follow-up 4 months after shunt surgery. Scores were compared to those of 44 healthy elderly control volunteers. CoGNIT was administered by either a nurse or an occupational therapist.

    RESULTS Improvement after shunt surgery was seen in all cognitive domains: memory (10-word list test, p < 0.01); executive functions (Stroop incongruent color and word test, p < 0.01); attention (2-choice reaction test, p < 0.01); psychomotor speed (Stroop congruent color and word test, p < 0.01); and manual dexterity (4-finger tapping, p < 0.01). No improvement was seen in the Mini-Mental State Examination score. Preoperative INPH test scores were significantly impaired compared to healthy control subjects (p < 0.001 for all tests).

    CONCLUSIONS In this study the feasibility for CoGNIT to detect a preoperative impairment and postoperative improvement in INPH was demonstrated. CoGNIT has the potential to become a valuable tool in clinical and research work.

  • 11.
    Behrens, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Lenfeldt, Niklas
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Ambarki, Khalid
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Koskinen, Lars-Owe D
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery.
    Intracranial Pressure and Pulsatility Index:  2011In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 69, no 4, p. E1033-E1034Article in journal (Refereed)
  • 12.
    Birnefeld, Johan
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Hansson, William
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Larsson, Jenny
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Björnfot, Cecilia
    Qvarlander, Sara
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Biomedical Laboratory Science. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Associations of cerebral arterial pulsatility, clinical symptoms and imaging features of cerebral small vessel diseaseManuscript (preprint) (Other academic)
  • 13.
    Birnefeld, Johan
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Petersson, Karl
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Eklund, Anders
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Birnefeld, Elin
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Qvarlander, Sara
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Haney, Michael
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Zarrinkoob, Laleh
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Cerebral blood flow assessed with phase-contrast magnetic resonance imaging during blood pressure changes with noradrenaline and labetalol: a trial in healthy volunteers 2024In: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 140, no 4, p. 669-678Article in journal (Refereed)
    Abstract [en]

    Background: Adequate cerebral perfusion is central during general anesthesia. However, perfusion is not readily measured bedside. Clinicians currently rely mainly on MAP as a surrogate even though the relationship between blood pressure and cerebral blood flow is not well understood. The aim of this study was to apply phase contrast MRI to characterize blood flow responses in healthy volunteers to commonly used pharmacological agents that increase or decrease arterial blood pressure.

    Methods: Eighteen healthy volunteers aged 30-50 years were investigated with phase contrast MRI. Intraarterial blood pressure monitoring was used. First, intravenous noradrenaline was administered to a target MAP of 20% above baseline. After a wash-out period, intravenous labetalol was given to a target MAP of 15% below baseline. Cerebral blood flow was measured using phase contrast MRI and defined as the sum of flow in the internal carotid arteries and vertebral arteries. CO was defined as the flow in the ascending aorta.

    Baseline median cerebral blood flow was 772 ml/min (interquartile range, 674 to 871), and CO was 5,874 ml/min (5,199 to 6,355). The median dose of noradrenaline was 0.17 µg · kg−1 · h−1 (0.14 to 0.22). During noradrenaline infusion, cerebral blood flow decreased to 705 ml/min (606 to 748; P = 0.001), and CO decreased to 4,995 ml/min (4,705 to 5,635; P = 0.01). A median dose of labetalol was 120 mg (118 to 150). After labetalol boluses, cerebral blood flow was unchanged at 769 ml/min (734 to 900; P = 0.68). CO increased to 6,413 ml/min (6,056 to 7,464; P = 0.03).

    Conclusion: In healthy awake subjects, increasing MAP using intravenous noradrenaline decreased cerebral blood flow and CO. This data does not support inducing hypertension with noradrenaline to increase cerebral blood flow. Cerebral blood flow was unchanged when decreasing MAP using labetalol.

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  • 14.
    Birnefeld, Johan
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences. Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Cerebral arterial pulsatility is associated with features of small vessel disease in patients with acute stroke and TIA: a 4D flow MRI study2020In: Journal of Neurology, ISSN 0340-5354, E-ISSN 1432-1459, Vol. 267, no 3, p. 721-730Article in journal (Refereed)
    Abstract [en]

    Cerebral small vessel disease (SVD) is a major cause of stroke and cognitive impairment. However, the underlying mechanisms behind SVD are still poorly understood. High cerebral arterial pulsatility has been suggested as a possible cause of SVD. In population studies, arterial pulsatility has been linked to white matter hyperintensities (WMH), cerebral atrophy, and cognitive impairment, all features of SVD. In stroke, pulsatility data are scarce and contradictory. The aim of this study was to investigate the relationship between arterial pulsatility and SVD in stroke patients. With a cross-sectional design, 89 patients with acute ischemic stroke or TIA were examined with MRI. A neuropsychological assessment was performed 1 year later. Using 4D flow MRI, pulsatile indices (PI) were calculated for the internal carotid artery (ICA) and middle cerebral artery (M1, M3). Flow volume pulsatility (FVP), a measure corresponding to the cyclic expansion of the arterial tree, was calculated for the same locations. These parameters were assessed for associations with WMH volume, brain volume and cognitive function. ICA-FVP was associated with WMH volume (β = 1.67, 95% CI: [0.1, 3.24], p = 0.037). M1-PI and M1-FVP were associated with decreasing cognitive function (β = - 4.4, 95% CI: [- 7.7, - 1.1], p = 0.009 and β = - 13.15, 95% CI: [- 24.26, - 2.04], p = 0.02 respectively). In summary, this supports an association between arterial pulsatility and SVD in stroke patients, and provides a potential target for further research and preventative treatment. FVP may become a useful biomarker for assessing pulsatile stress with PCMRI and 4D flow MRI.

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  • 15.
    Bodén, Ida
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nilsson, David
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Forssell, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Naredi, Peter
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Lindholm-Sethson, Britta
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    In vivo skin measurements with a novel probe head for simultaneous skin impedance and near-infrared spectroscopy2011In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 17, no 4, p. 494-504Article in journal (Refereed)
    Abstract [en]

    Background/purpose: Near-infrared (NIR) spectroscopy and skin impedance (IMP) measurements are useful techniques for objective diagnostics of various skin diseases. Here, we present a combined probe head for simultaneous, time-saving NIR spectroscopy and skin impedance measurements. The probe also ensures that both measurements are performed under equal conditions and at the same skin location.

    Methods: Finite element method simulations were performed for evaluation of the impedance. In vivo skin measurements were performed and combined NIR and impedance spectra were analysed by means of multivariate methods with respect to body location, age and gender. The classification rate was determined by a planar discriminant analysis. Reproducibility was investigated by calculation of scatter values and statistical significance between overlapping groups was assessed by the calculation of intra-model distances, q.

    Results: The novel probe yielded rapid reproducible results and was easy to manage. Significant differences between skin locations and to a lesser extent age groups and gender were demonstrated.

    Conclusion: With the novel probe, statistically significant differences between overlapping classes in score plots can be confirmed by calculating intra-model distances. The influence of molecular differences in the skin at different body locations is larger than the influence of gender or age and therefore relevant reference measurements are discussed.

  • 16.
    Bodén, Ida
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Nilsson, David
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Naredi, Peter
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Lindholm-Sethson, Britta
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Characterization of healthy skin using near infrared spectroscopy and skin impedance2008In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 46, no 10, p. 985-995Article in journal (Refereed)
    Abstract [en]

    Near infrared spectroscopy (NIR) and skin impedance (IMP) spectroscopy are two methods suggested for diagnoses of diseases inducing adverse effects in skin. The reproducibility of these methods and their potential value in non-invasive diagnostics were investigated. Measurements were performed in vivo on healthy skin at five anatomic body sites on eight young women. partial least squares discriminant analysis showed that both methods were useful for classification of the skin characteristics at the sites. Inter-individually the NIR model gave 100% correct classification while the IMP model provided 92%. Intra-individually the NIR model gave 88% correct classification whereas the IMP model did not provide any useful classification. The correct classification was increased to 93% when both datasets were combined, which demonstrates the value of adding information. Partial least squares discriminant analysis gave 72% correct predictions of skin sites while the combined model slightly improved to 73%.

  • 17.
    Bodén, Ida
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Nyström, Josefina
    Swedish University of Agricultural Sciences, Unit of Biomass Technology and Chemistry.
    Geladi, Paul
    Swedish University of Agricultural Sciences, Unit of Biomass Technology and Chemistry.
    Naredi, Peter
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Lindholm-Sethson, Britta
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    NIR and skin impedance spectroscopic measurements for studying the effect of coffee and alcohol on skin, and dysplastic naevi2012In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 18, no 4, p. 486-494Article in journal (Refereed)
    Abstract [en]

    Background/purpose: Near infrared (NIR) and impedance spectroscopy can be used for clinical skin measurements and need to be evaluated for possible confounding factors; (a) are skin conditions of the patient and the subsequent skin measurements influenced by alcohol and/or coffee consumption and (b) are measurements of dysplastic naevi (DN) reproducible over time and significantly different compared to reference skin.

    Methods: NIR and skin impedance spectroscopic data were analysed multivariately. In the first study, the skin characteristics of 15 healthy individuals were examined related to body location, gender, individual differences, and consumption of coffee or alcohol. The second study included five patients diagnosed with dysplastic naevi syndrome (DNS). Measurements were taken on DN and reference skin over time.

    Results: In the first study, body location and gender had a major influence on measurement scores. Inter-individual skin characteristics and coffee or alcohol effects on skin characteristics were of minor importance. In the second study, it was shown that DN can be differentiated from reference skin and the measurements are stable over time.

    Conclusions: Moderate consumption of alcohol and coffee did not influence the results of the measurements. It is possible to follow, stable or changed, characteristics of DN over time.

  • 18.
    Brändström, Helge
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Hallberg, Per
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Grönlund, Christer
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Ängquist, Karl-Axel
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Giesbrecht, Gordon G
    Hand cold recovery responses before and after 15 months of military training in a cold climate2008In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 79, no 9, p. 904-908Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: The ability of fingers to rapidly rewarm following cold exposure is a possible indicator of cold injury protection. We categorized the post-cooling hand-rewarming responses of men before and after participation in 15 mo of military training in a cold environment in northern Sweden to determine: 1) if the initial rewarming category was related to the occurrence of local cold injury during training; and 2) if cold training affected subsequent hand-rewarming responses. METHODS: Immersion of the dominant hand in 10 degrees C water for 10 min was performed pre-training on 77 men. Of those, 45 were available for successful post-training retests. Infrared thermography monitored the dorsal hand during 30 min of recovery. Rewarming was categorized as normal, moderate, or slow based on mean fingertip temperature at the end of 30 min of recovery (TFinger,30) and the percentage of time that fingertips were vasodilated (%VD). RESULTS: Cold injury occurrence during training was disproportionately higher in the slow rewarmers (four of the five injuries). Post-training, baseline fingertip temperatures and cold recovery variables increased significantly in moderate and slow rewarmers: TFinger30 increased from 21.9 +/- 4 to 30.4 +/- 6 degrees C (Moderate), and from 17.4 +/- 0 to 22.3 +/- 7 degrees C (Slow); %VD increased from 27.5 +/- 16 to 65.9 +/- 34% (Moderate), and from 0.7 +/- 2 to 31.7 +/- 44% (Slow). CONCLUSIONS: Results of the cold recovery test were related to the occurrence of local cold injury during long-term cold-weather training. Cold training itself improved baseline and cold recovery in moderate and slow rewarmers.

  • 19.
    Burström, Lage
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Hagberg, Mats
    Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Box 414, SE-405 30 Gothenburg, Sweden.
    Liljelind, Ingrid
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Lundström, Ronnie
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Nilsson, Tohr
    Department of Occupational and Environmental Medicine, Sundsvall Hospital, Sundsvall, SE-851 86 Sweden.
    Pettersson, Hans
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Wahlström, Jens
    Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Box 414, SE-405 30 Gothenburg, Sweden.
    A follow-up study of welders’ exposure to vibration in a heavy engineering production workshop2010In: Journal of Low Frequency Noise Vibration and Active Control, ISSN 0263-0923, Vol. 29, no 1, p. 33-39Article in journal (Refereed)
    Abstract [en]

    Manual work involving vibrating power tools is associated with symptoms that include vascular, neurological and musculoskeletal disorders. This study examines the vibration exposure of welders to determine the change between 1987 and 2008. Vibration measurements on handheld tools were used to evaluate the acceleration and the daily exposure time was determined by subjective rating. From these data, the 8-hour equivalent vibration exposure A(8), has been calculated. During the period, the A(8) decreased from 3.9 m/s2 to 1.9 m/s2. It was concluded that this decrease is the result of fewer vibrating tools and a decrease in daily exposure time. Although the daily vibration exposure has decreased over the study time, for some welders the daily vibration exposure A(8) is still above the action value set by the EU directive on vibration. This means more effort should be spent to decrease vibration exposure.

  • 20.
    Candefjord, Stefan
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Computer Science Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden; Signals and Systems, Chalmers University of Technology, Gothenburg, Sweden; MedTech West, Sahlgrenska University Hospital, Gothenburg, Sweden.
    Murayama, Yoshinobu
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Electrical and Electronics Engineering, College of Engineering, Nihon University, Fukushima, Japan.
    Nyberg, Morgan
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
    Hallberg, Josef
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Computer Science Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
    Ramser, Kerstin
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Computer Science Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
    Ljungberg, Börje
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Urology and Andrology.
    Bergh, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lindahl, Olof Anton
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences. Department of Computer Science Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
    Combining scanning haptic microscopy and fibre optic Raman spectroscopy for tissue characterization2012In: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 36, no 6, p. 319-327Article in journal (Refereed)
    Abstract [en]

    The tactile resonance method (TRM) and Raman spectroscopy (RS) are promising for tissue characterization in vivo. Our goal is to combine these techniques into one instrument, to use TRM for swift scanning, and RS for increasing the diagnostic power. The aim of this study was to determine the classification accuracy, using support vector machines, for measurements on porcine tissue and also produce preliminary data on human prostate tissue. This was done by developing a new experimental set-up combining micro-scale TRMscanning haptic microscopy (SHM)for assessing stiffness on a micro-scale, with fibre optic RS measurements for assessing biochemical content. We compared the accuracy using SHM alone versus SHM combined with RS, for different degrees of tissue homogeneity. The cross-validation classification accuracy for healthy porcine tissue types using SHM alone was 6581%, and when RS was added it increased to 8187%. The accuracy for healthy and cancerous human tissue was 6770% when only SHM was used, and increased to 7277% for the combined measurements. This shows that the potential for swift and accurate classification of healthy and cancerous prostate tissue is high. This is promising for developing a tool for probing the surgical margins during prostate cancer surgery. 

  • 21.
    Candefjord, Stefan
    et al.
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Nyberg, Morgan
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Jalkanen, Ville
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ramser, Kerstin
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Combining fibre optic Raman spectroscopy and tactile resonance measurement for tissue characterization2010In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 21, no 125801, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Tissue characterization is fundamental for identification of pathological conditions. Raman spectroscopy (RS) and tactile resonance measurement (TRM) are two promising techniques that measure biochemical content and stiffness, respectively. They have potential to complement the golden standard-–histological analysis. By combining RS and TRM, complementary information about tissue content can be obtained and specific drawbacks can be avoided. The aim of this study was to develop a multivariate approach to compare RS and TRM information. The approach was evaluated on measurements at the same points on porcine abdominal tissue. The measurement points were divided into five groups by multivariate analysis of the RS data. A regression analysis was performed and receiver operating characteristic (ROC) curves were used to compare the RS and TRM data. TRM identified one group efficiently (area under ROC curve 0.99). The RS data showed that the proportion of saturated fat was high in this group. The regression analysis showed that stiffness was mainly determined by the amount of fat and its composition. We concluded that RS provided additional, important information for tissue identification that was not provided by TRM alone. The results are promising for development of a method combining RS and TRM for intraoperative tissue characterization.

  • 22.
    Candefjord, Stefan
    et al.
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Nyberg, Morgan
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Jalkanen, Ville
    Umeå University, Faculty of Science and Technology, Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics.
    Ramser, Kerstin
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Evaluating the use of a Raman fiberoptic probe in conjunction with a resonance sensor for measuring porcine tissue in vitro2009In: IFMBE Proceedings of the World Congress on Medical Physics and Biomedical Engineering, Heidelberg: Springer , 2009, p. 414-417Conference paper (Refereed)
    Abstract [en]

    Prostate cancer is the most common form of cancer and is the third leading cause of cancer-related death in European men. There is a need for new methods that can accurately localize and diagnose prostate cancer. In this study a new approach is presented: a combination of resonance sensor technology and Raman spectroscopy. Both methods have shown promising results for prostate cancer detection in vitro. The aim of this study was to evaluate the combined information from measurements with a Raman fiberoptic probe and a resonance sensor system. Pork belly tissue was used as a model system. A three-dimensional translation table was equipped with an in-house developed software, allowing measurements to be performed at the same point using two separate instruments. The Raman data was analyzed using principal component analysis and hierarchical clustering analysis. The spectra were divided into 5 distinct groups. The mean stiffness of each group was calculated from the resonance sensor measurements. One of the groups differed significantly (p < 0.05) from the others. A regression analysis, with the stiffness parameter as response variable and the principal component scores of the Raman data as the predictor variables, explained 67% of the total variability. The use of a smaller resonance sensor tip would probably increase the degree of correlation. In conclusion, Raman spectroscopy provides additional discriminatory power to the resonance sensor.

  • 23.
    Candefjord, Stefan
    et al.
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Nyberg, Morgan
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Jalkanen, Ville
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Ramser, Kerstin
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Kombinationsinstrument för detektering av prostatacancer: korrelation mellan resonanssensor och fiberoptisk Ramanprobe2009In: Medicinteknikdagarna 2009, Svensk förening för medicinsk teknik och fysik , 2009, p. 60-Conference paper (Refereed)
  • 24.
    Dunås, Tora
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Ambarki, Khalid
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Zarrinkoob, Laleh
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    A Stereotactic Probabilistic Atlas for the Major Cerebral Arteries2017In: Neuroinformatics, ISSN 1539-2791, E-ISSN 1559-0089, Vol. 15, no 1, p. 101-110Article in journal (Refereed)
    Abstract [en]

    Improved whole brain angiographic and velocity-sensitive MRI is pushing the boundaries of noninvasively obtained cerebral vascular flow information. The complexity of the information contained in such datasets calls for automated algorithms and pipelines, thus reducing the need of manual analyses by trained radiologists. The objective of this work was to lay the foundation for such automated pipelining by constructing and evaluating a probabilistic atlas describing the shape and location of the major cerebral arteries. Specifically, we investigated how the implementation of a non-linear normalization into Montreal Neurological Institute (MNI) space improved the alignment of individual arterial branches. In a population-based cohort of 167 subjects, age 64-68 years, we performed 4D flow MRI with whole brain volumetric coverage, yielding both angiographic and anatomical data. For each subject, sixteen cerebral arteries were manually labeled to construct the atlas. Angiographic data were normalized to MNI space using both rigid-body and non-linear transformations obtained from anatomical images. The alignment of arterial branches was significantly improved by the non-linear normalization (p < 0.001). Validation of the atlas was based on its applicability in automatic arterial labeling. A leave-one-out validation scheme revealed a labeling accuracy of 96 %. Arterial labeling was also performed in a separate clinical sample (n = 10) with an accuracy of 92.5 %. In conclusion, using non-linear spatial normalization we constructed an artery-specific probabilistic atlas, useful for cerebral arterial labeling.

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  • 25.
    Dunås, Tora
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Zarrinkoob, Laleh
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Ambarki, Khalid
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Towards Automatic Identification of Cerebral Arteries in 4D Flow MRI2015In: 16th Nordic-Baltic Conference on Biomedical Engineering / [ed] Henrik Mindedal, Mikael Persson, 2015, Vol. 48, p. 40-43Conference paper (Refereed)
    Abstract [en]

    4D flow MRI is a powerful imaging technique which provides an angiographic image with information about blood flow in a large volume, time resolved over the cardiac cycle, in a short imaging time. This study aims to develop an automatic method for identification of cerebral arteries. The proposed method is based on an atlas of twelve arteries, developed from 4D flow MRI of 25 subjects. The atlas was constructed by normalizing all images to MNI-space, manually identifying the arteries and creating an average over the volume. The identification is done by extracting a vascular skeleton from the image, transforming it to MNI-space, labeling it with the atlas and transforming it back to subject space. The method was evaluated on a pilot cohort of 8 subjects. The rate of correctly identified arteries was 97%.

  • 26.
    Duvaldt, Maria
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Karolinska Universitetssjukhuset Huddinge.
    Developing a Semi-Automatised Tool for Grading Brain Tumours with Susceptibility-Weighted MRI2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Gliomas are a common type of brain tumour and for the treatment of a patient it is important to determine the tumour’s grade of malignancy. This is done today by a biopsy, a histopathological analysis of the tumourous tissue, that is classified by the World Health Organization on a malignancy scale from I to IV. Recent studies have shown that the local image variance (LIV) and the intratumoural susceptibility signal (ITSS) in susceptibility-weighted MR images correlate to the tumour grade. This thesis project aims to develop a software program as aid for the radiologists when grading a glioma. The software should by image analysis be able to separate the gliomas into low grade (I-II) and high grade (III-IV). The result is a graphical user interface written in Python 3.4.3. The user chooses an image, draws a region of interest and starts the analysis. The analyses implemented in the program are LIV and ITSS mentioned above, and the code can be extended to contain other types of analyses as research progresses. To validate the image analysis, 16 patients with glioma grades confirmed by biopsy are included in the study. Their susceptibility-weighted MR images were analysed with respect to LIV and ITSS, and the outcome of those image analyses was tested versus the known grades of the patients. No statistically significant difference could be seen between the high and the low grade group, in the case of LIV. This was probably due to hemorrhage and calcification, characteristic for some tumours and interpreted as blood vessels. Concerning ITSS a statistically significant difference could be seen between the high and the low grade group (p < 0.02). The sensitivity and specificity was 80% and 100% respec- tively. Among these 16 gliomas, 11 were astrocytic tumours and between low and high grade astrocytomas a statistically significant difference was shown. The degree of LIV was significantly different between the two groups (p < 0.03) and the sensitivity and specificity were 86% and 100% respectively. The degree of ITSS was significantly different between the two groups (p < 0.04) and the sensitivity and specificity were 86% and 100% respectively. Spearman correlation showed a correlation between LIV and tumour grade (for all gliomas r = 0.53 and p < 0.04, for astrocytomas r = 0.84 and p < 0.01). A correlation was also found between ITSS and tumour grade (for all gliomas r = 0.69 and p < 0.01, for astrocytomas r = 0.63 and p < 0.04). The results indicate that SWI is useful for distinguishing between high and low grade astrocytoma with 1.5T imaging within this cohort. It also seems possible to distinguish between high and low grade glioma with ITSS.

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  • 27.
    Eklund, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Jóhannesson, Gauti
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Johansson, Elias
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Pharmacology.
    Holmlund, Petter
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Qvarlander, Sara
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Ambarki, Khalid
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Koskinen, Lars-Owe D.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Pharmacology.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    The Pressure Difference between Eye and Brain Changes with Posture2016In: Annals of Neurology, ISSN 0364-5134, E-ISSN 1531-8249, Vol. 80, no 2, p. 269-276Article in journal (Refereed)
    Abstract [en]

    Objective: The discovery of a posture-dependent effect on the difference between intraocular pressure (IOP) and intracranial pressure (ICP) at the level of lamina cribrosa could have important implications for understanding glaucoma and idiopathic intracranial hypertension and could help explain visual impairments in astronauts exposed to microgravity. The aim of this study was to determine the postural influence on the difference between simultaneously measured ICP and IOP.

    Methods: Eleven healthy adult volunteers (age = 46 ± 10 years) were investigated with simultaneous ICP, assessed through lumbar puncture, and IOP measurements when supine, sitting, and in 9° head-down tilt (HDT). The trans–lamina cribrosa pressure difference (TLCPD) was calculated as the difference between the IOP and ICP. To estimate the pressures at the lamina cribrosa, geometrical distances were estimated from magnetic resonance imaging and used to adjust for hydrostatic effects.

    Results: The TLCPD (in millimeters of mercury) between IOP and ICP was 12.3 ± 2.2 for supine, 19.8 ± 4.6 for sitting, and 6.6 ± 2.5 for HDT. The expected 24-hour average TLCPD on earth—assuming 8 hours supine and 16 hours upright—was estimated to be 17.3mmHg. By removing the hydrostatic effects on pressure, a corresponding 24-hour average TLCPD in microgravity environment was simulated to be 6.7mmHg.

    Interpretation: We provide a possible physiological explanation for how microgravity can cause symptoms similar to those seen in patients with elevated ICP. The observed posture dependency of TLCPD also implies that assessment of the difference between IOP and ICP in upright position may offer new understanding of the pathophysiology of idiopathic intracranial hypertension and glaucoma. 

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  • 28.
    Eklund, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lindén, Christina
    Umeå University, Faculty of Medicine, Department of Clinical Sciences.
    Bäcklund, Tomas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Andersson, Britt M
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Lindahl, Olof A
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Evaluation of applanation resonator sensors for intra-ocular pressure measurement: results from clinical and in vitro studies.2003In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, no 2, p. 190-197Article in journal (Refereed)
    Abstract [en]

    Glaucoma is an eye disease that, in its most common form, is characterised by high intra-ocular pressure (IOP), reduced visual field and optic nerve damage. For diagnostic purposes and for follow-up after treatment, it is important to have simple and reliable methods for measuring IOP. Recently, an applanation resonator sensor (ARS) for measuring IOP was introduced and evaluated using an in vitro pig-eye model. In the present study, the first clinical evaluation of the same probe has been carried out, with experiments in vivo on human eyes. There was a low but significant correlation between IOP(ARS) and the IOP measured with a Goldmann applanation tonometer (r = 0.40, p = 0.001, n = 72). However, off-centre positioning of the sensor against the cornea caused a non-negligible source of error. The sensor probe was redesigned to have a spherical, instead of flat, contact surface against the eye and was evaluated in the in vitro model. The new probe showed reduced sensitivity to off-centre positioning, with a decrease in relative deviation from 89% to 11% (1 mm radius). For normalised data, linear regression between IOP(ARS) and direct IOP measurement in the vitreous chamber showed a correlation of r = 0.97 (p < 0.001, n = 108) and a standard deviation for the residuals of SD < or = 2.18 mm Hg (n = 108). It was concluded that a spherical contact surface should be preferred and that further development towards a clinical instrument should focus on probe design and signal analysis.

  • 29. Ertzgaard, Per
    et al.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Gerdle, Björn
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    A new way of assessing arm function in activity using kinematic Exposure Variation Analysis and portable inertial sensors - A validity study2016In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 21, p. 241-249Article in journal (Refereed)
    Abstract [en]

    Portable motion systems based on inertial motion sensors are promising methods, with the advantage compared to optoelectronic cameras of not being confined to a laboratory setting. A challenge is to develop relevant outcome measures for clinical use. The aim of this study was to characterize elbow and shoulder motion during functional tasks, using portable motion sensors and a modified Exposure Variation Analysis (EVA) and evaluate system accuracy with optoelectronic cameras. Ten healthy volunteers and one participant with sequel after stroke performed standardised functional arm tasks. Motion was registered simultaneously with a custom developed motion sensor system, including gyroscopes and accelerometers, and an optoelectronic camera system. The EVA was applied on elbow and shoulder joints, and angular and angular velocity EVA plots was calculated. The EVA showed characteristic patterns for each arm task in the healthy controls and a distinct difference between the affected and unaffected arm in the participant with sequel after stroke. The accuracy of the portable system was high with a systematic error ranging between -1.2 degrees and 2.0 degrees. The error was direction specific due to a drift component along the gravity vector. Portable motion sensor systems have high potential as clinical tools for evaluation of arm function. EVA effectively illustrates joint angle and joint angle velocity patterns that may capture deficiencies in arm function and movement quality. Next step will be to manage system drift by including magnetometers, to further develop clinically relevant outcome variables and apply this for relevant patient groups.

  • 30.
    Fortuin-De Smidt, Melony C.
    et al.
    Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa; Non-Communicable Diseases Research Unit, South African Medical Council, Tygerberg, South Africa.
    Mendham, Amy E.
    Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa; Non-Communicable Diseases Research Unit, South African Medical Council, Tygerberg, South Africa.
    Hauksson, Jon
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Alhamud, Ali
    Department of Human Biology, MRC/UCT Medical Imaging Research Unit, University of Cape Town, Cape Town, South Africa; The Modern Pioneer Center and ArSMRM for MRI Training and Development, Tripoli, Libyan Arab Jamahiriya.
    Stefanovski, Darko
    Department of Clinical Studies, New Bolton Centre, University of Pennsylvania, School of Veterinary Medicine, PA, Kennett Square, United States.
    Hakim, Olah
    Department of Diabetes, Faculty of Life Sciences and Medicine, School of Life Course Sciences, King’s College London, London, United Kingdom.
    Swart, Jeroen
    Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
    Goff, Louise M.
    Department of Diabetes, Faculty of Life Sciences and Medicine, School of Life Course Sciences, King’s College London, London, United Kingdom.
    Kahn, Steven E.
    Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, Veterans Affairs Puget Sound Health Care System, University of Washington, WA, Seattle, United States.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Goedecke, Julia H.
    Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa; Non-Communicable Diseases Research Unit, South African Medical Council, Tygerberg, South Africa.
    β-cell function in black South African women: Exploratory associations with insulin clearance, visceral and ectopic fat2021In: Endocrine Connections, E-ISSN 2049-3614, Vol. 10, no 5, p. 550-560Article in journal (Refereed)
    Abstract [en]

    The role of ectopic fat, insulin secretion and clearance in the preservation of β-cell function in black African women with obesity who typically present with hyperinsulinaemia is not clear. We aim to examine the associations between disposition index (DI, an estimate of β-cell function), insulin secretion and clearance and ectopic fat deposition. This is a cross-sectional study of 43 black South African women (age 20–35 years) with obesity (BMI 30–40 kg/m2) and without type 2 diabetes that measured the following: DI, insulin sensitivity (SI), acute insulin response (AIRg), insulin secretion rate (ISR), hepatic insulin extraction and peripheral insulin clearance (frequently sampled i.v. glucose tolerance test); pancreatic and hepatic fat, visceral adipose tissue (VAT) and abdominal s.c. adipose tissue (aSAT) volume (MRI), intra-myocellular (IMCL) and extra-myocellular fat content (EMCL) (magnetic resonance spectroscopy). DI correlated positively with peripheral insulin clearance (β 55.80, P = 0.002). Higher DI was associated with lower VAT, pancreatic fat and soleus fat, but VAT explained most of the variance in DI (32%). Additionally, higher first phase ISR (P = 0.033) and lower hepatic insulin extraction (P = 0.022) were associated with lower VAT, independent from SI, rather than with ectopic fat. In conclusion, peripheral insulin clearance emerged as an important correlate of DI. However, VAT was the main determinant of a lower DI above ectopic fat depots. Importantly, VAT, but not ectopic fat, is associated with both lower insulin secretion and higher hepatic insulin extraction. Prevention of VAT accumulation in young black African women should, therefore, be an important target for beta cell preservation.

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  • 31. Fortuin-de Smidt, Melony C.
    et al.
    Mendham, Amy E.
    Hauksson, Jon
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Hakim, Olah
    Stefanovski, Darko
    Clamp, Louise
    Phiri, Lindokuhle
    Swart, Jeroen
    Goff, Louise M.
    Micklesfield, Lisa K.
    Kahn, Steven E.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Goedecke, Julia H.
    Effect of exercise training on insulin sensitivity, hyperinsulinemia and ectopic fat in black South African women: a randomized controlled trial2020In: European Journal of Endocrinology, ISSN 0804-4643, E-ISSN 1479-683X, Vol. 183, no 1, p. 51-61Article in journal (Refereed)
    Abstract [en]

    Objective: We investigated the effects of a 12-week exercise intervention on insulin sensitivity (SI) and hyperinsulinemia and associated changes in regional and ectopic fat.

    Research design and methods: Healthy, black South African women with obesity (mean age 23 ± 3.5 years) and of isiXhosa ancestry were randomised into a 12-week aerobic and resistance exercise training group (n = 23) and a no exercise group (control, n = 22). Pre and post-intervention testing included assessment of SI, insulin response to glucose (AIRg), insulin secretion rate (ISR), hepatic insulin extraction (FEL) and disposition index (DI) (AIRg × SI) (frequently sampled i.v. glucose tolerance test); fat mass and regional adiposity (dual-energy X-ray absorptiometry); hepatic, pancreatic and skeletal muscle fat content and abdominal s.c. and visceral adipose tissue volumes (MRI).

    Results: Exercise training increased VO2peak (mean ± s.d.: 24.9 ± 2.42 to 27.6 ± 3.39 mL/kg/min, P < 0.001), SI (2.0 (1.2–2.8) to 2.2 (1.5–3.7) (mU/l)−1 min−1, P = 0.005) and DI (median (interquartile range): 6.1 (3.6–7.1) to 6.5 (5.6–9.2) × 103 arbitrary units, P = 0.028), and decreased gynoid fat mass (18.5 ± 1.7 to 18.2 ± 1.6%, P < 0.001) and body weight (84.1 ± 8.7 to 83.3 ± .9.7 kg, P = 0.038). None of these changes were observed in the control group, but body weight increased (P = 0.030). AIRg, ISR and FEL, VAT, SAT and ectopic fat were unaltered after exercise training. The increase in SI and DI were not associated with changes in regional or ectopic fat.

    Conclusion: Exercise training increased SI independent from changes in hyperinsulinemia and ectopic fat, suggesting that ectopic fat might not be a principal determinant of insulin resistance in this cohort.

  • 32. Gerdle, Björn
    et al.
    Östlund, Nils
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Biomedical Engineering and Informatics, University Hospital, Umeå, Sweden.
    Grönlund, Christer
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Biomedical Engineering and Informatics, University Hospital, Umeå, Sweden.
    Roeleveld, Karin
    Karlsson, Stefan
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Biomedical Engineering and Informatics, University Hospital, Umeå, Sweden.
    Firing rate and conduction velocity of single motor units in the trapezius muscle in fibromyalgia patients and healthy controls2008In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 18, no 5, p. 707-716Article in journal (Refereed)
    Abstract [en]

    Fibromyalgia is a common chronic pain condition in the population (2-4%), which often is associated with prominent negative consequences with respect to participation in daily activities. There are several reports in the literature concerning the effects of acute experimental pain on motor control. However, a more heterogeneous picture exists in the literature with respect to whether chronic pain conditions affect motor control. This study compares firing rate and conduction velocity (CV) of single motor units (MUs) in the trapezius muscle of fibromyalgia patients (FM) and healthy controls (CON). Multi-channel surface electromyography was used to estimate both MU firing rate and CV because this technique allows simultaneous estimation of both these variables and the measurements are easy and non-invasive. In this study, 29 FM and 30 CON subjects participated and performed isometric shoulder elevations using weights up to 4 kg. No significant differences in the firing rate of MUs in the trapezius muscle were found between the FM and CON groups (95% confidence interval was -1.9 and 1.3 pulses per second). There were no significant differences in CV between the groups at 1 and 2 kg load. However, the FM group had significantly higher CV in contractions without external load (p=0.004). We were unable to confirm the pain-adaptation model since no differences in firing rate between the two groups were found. CV was significantly higher in FM than in healthy controls; this might be due to alterations in histopathology and microcirculation.

  • 33.
    Grönlund, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Claesson, Kenji
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    D'hooge, Jan
    Department of Cardiovascular sciences, Leuven, Belgium.
    Henein, Michael Y.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology. Umeå Heart Centre.
    Lindqvist, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology. Umeå Heart Centre.
    Simultaneous quantification of myocardial and blood flow velocities based on duplex mode ultrasound imaging2013In: Biomedical engineering online, E-ISSN 1475-925X, Vol. 12, article id 107Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Ultrasound imaging of the heart is a commonly used clinical tool to assess cardiac function. The basis for this analysis is the quantification of cardiac blood flow and myocardial velocities. These are typically measured using different imaging modes and on different cardiac cycles. However, due to beat-to-beat variations such as irregular heart rhythm and transient events, simultaneous acquisition is preferred. There exists specialized ultrasound systems for this purpose; however, it would be beneficial if this could be achieved using conventional ultrasound systems due to their wide availability. The conventional Duplex mode ultrasound allows simultaneous acquisition, however at a highly reduced spatial and temporal resolution.

    METHODS: The aim of this work was to present and evaluate the performance of a novel method to recover myocardial tissue velocity using conventional Duplex ultrasound imaging, and to demonstrate its feasibility for the assessment of simultaneous blood flow and myocardial velocity in-vivo. The essence of the method was the estimation of the axial phase shift of robust echogenic structures between subsequent image frames. The performance of the method was evaluated on synthetic tissue mimicking B-mode image sequences at different frame rates (20--60 Hz) and tissue velocities (peak velocities 5-15cm/s), using cardiac deformation and displacement characteristics. The performance was also compared to a standard 2-D speckle tracking technique.

    RESULTS: The method had an overall high performance at frame rates above 25 Hz, with less than 15% error of the peak diastolic velocity, and less than 10 ms peak timing error. The method showed superior performance compared to the 2-D tracking technique at frame rates below 50 Hz. The in-vivo quantification of simultaneous blood flow and myocardial tissue velocities verified the echocardiographic patterns and features of healthy subjects and the specific patient group.

    CONCLUSIONS: A novel myocardial velocity quantification method was presented and high performance at frame rates above 25Hz was shown. In-vivo quantification of simultaneous myocardial and blood flow velocities was feasible using the proposed method and conventional Duplex mode imaging. We propose that the methodology is suitable for retrospective as well as prospective studies on the mechanics and hemodynamics of the heart.

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  • 34.
    Grönlund, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Claesson, Kenji
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Holtermannz, Andreas
    Imaging two-dimensional mechanical waves of skeletal muscle contraction2013In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 39, no 2, p. 360-369Article in journal (Refereed)
    Abstract [en]

    Skeletal muscle contraction is related to rapid mechanical shortening and thickening. Recently, specialized ultrasound systems have been applied to demonstrate and quantify transient tissue velocities and one-dimensional (1-D) propagation of mechanical waves during muscle contraction. Such waves could potentially provide novel information on musculoskeletal characteristics, function and disorders. In this work, we demonstrate two-dimensional (2-D) mechanical wave imaging following the skeletal muscle contraction. B-mode image acquisition during multiple consecutive electrostimulations, speckle-tracking and a time-stamp sorting protocol were used to obtain 1.4 kHz frame rate 2-D tissue velocity imaging of the biceps brachii muscle contraction. The results present novel information on tissue velocity profiles and mechanical wave propagation. In particular, counter-propagating compressional and shear waves in the longitudinal direction were observed in the contracting tissue (speed 2.8-4.4 m/s) and a compressional wave in the transverse direction of the non-contracting muscle tissue (1.2-1.9 m/s). In conclusion, analysing transient 2-D tissue velocity allows simultaneous assessment of both active and passive muscle tissue properties. (E-mail: christer.gronlund@vll.se) (C) 2013 World Federation for Ultrasound in Medicine & Biology.

  • 35.
    Grönlund, Christer
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Östlund, Nils
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lindh, Jack
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Bergström, Per
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Karlsson, Stefan J
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Spatio-temporal processing of surface EMG signals from the sternocleidomastoideus muscle to assess effects of radiotherapy on motor unit conduction velocity and firing rate: a pilot study2008In: Biomedical Signal Processing and Control, ISSN 1746-8094, Vol. 3, no 2, p. 163-168Article in journal (Refereed)
    Abstract [en]

    Radiation therapy causes both muscle and nerve tissue damage. However, the evolution and mechanisms of these damages are not fully understood. Information on the state of active muscle fibres and motoneurons can be obtained by measuring sEMG signals and calculating the conduction velocity (CV) and firing rate of individual motor units, respectively. The aim of this pilot study was to evaluate if the multi-channel surface EMG (sEMG) technique could be applied to the sternocleidomastoideus muscle (SCM) of radiotherapy patients, and to assess if the CV and firing rate are altered as a consequence of the radiation.

    Surface EMG signals were recorded from the radiated and healthy SCM muscles of 10 subjects, while subjects performed isometric rotation of the head. CV and firing rate were calculated using two recently proposed methods based on spatio-temporal processing of the sEMG signals. The multi-channel sEMG technique was successfully applied to the SCM muscle and CV and firing rates were obtained. The measurements were fast and simple and comfortable for the patients. Sufficient data quality was obtained from both sides of seven and four subjects for the CV and firing rate analysis, respectively. No differences in CV or firing rate were found between the radiated and non-radiated sides (p = 0.13 and p = 0.20, respectively). Firing rate and CV were also obtained from a myokymic discharge pattern. It was found that the CV decreased significantly (p = 0.01) during the bursts.

  • 36.
    Gustavsson, Sandra
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Granåsen, Gabriel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Grönlund, Christer
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Mörner, Stellan
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Henein, Michael
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Suhr, Ole B
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Lindqvist, Per
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Can echocardiography and ECG discriminate hereditary transthyretin V30M amyloidosis from hypertrophic cardiomyopathy?2015In: Amyloid: Journal of Protein Folding Disorders, ISSN 1350-6129, E-ISSN 1744-2818, Vol. 22, no 3, p. 163-170Article in journal (Refereed)
    Abstract [en]

    Objective: Hereditary transthyretin (ATTR) amyloidosis with increased left ventricular wall thickness could easily be misdiagnosed by echocardiography as hypertrophic cardiomyopathy (HCM). Our aim was to create a diagnostic tool based on echocardiography and ECG that could optimise identification of ATTR amyloidosis. Methods: Data were analysed from 33 patients with biopsy proven ATTR amyloidosis and 30 patients with diagnosed HCM. Conventional features from ECG were acquired as well as two dimensional and Doppler echocardiography, speckle tracking derived strain and tissue characterisation analysis. Classification trees were used to select the most important variables for differentiation between ATTR amyloidosis and HCM. Results: The best classification was obtained using both ECG and echocardiographic features, where a QRS voltage >30 mm was diagnostic for HCM, whereas in patients with QRS voltage <30 mm, an interventricular septal/posterior wall thickness ratio (IVSt/PWt) >1.6 was consistent with HCM and a ratio <1.6 supported the diagnosis of ATTR amyloidosis. This classification presented both high sensitivity (0.939) and specificity (0.833). Conclusion: Our study proposes an easily interpretable classification method for the differentiation between HCM and increased left ventricular myocardial thickness due to ATTR amyloidosis. Our combined echocardiographic and ECG model could increase the ability to identify ATTR cardiac amyloidosis in clinical practice.

  • 37.
    Hallberg, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Lindén, Christina
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Bäcklund, Tomas
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Symmetric sensor for applanation resonance tonometry of the eye2006In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, no 1-2, p. 54-60Article in journal (Refereed)
    Abstract [en]

    Applanation resonance tonometry (ART) has been shown in a number of studies to be useful for measuring intraocular pressure (IOP). Data from in vitro laboratory bench testing, where the sensor was carefully centralised onto the cornea, has been very consistent with good precision in the determination of IOP. However, in a clinical study the unavoidable off-centre placement of the sensor against the cornea resulted in a reduced precision. The aim of this study was to evaluate a new design of the sensor with a symmetric sensor probe and a contact piece with a larger diameter. Two in vitro porcine eye experimental set-ups were used. One bench-based for examining position dependence and one biomicroscope-based set-up, simulating a clinical setting, for evaluating IOP(ART) precision at seven different pressure levels (1040 mmHg), set by connecting a saline column to the vitreous chamber. The reference IOP was recorded using a pressure transducer. There was no significant difference between four positions 1 mm off centre and the one centre position. The precision of the ART as compared with the reference pressure was +/- 1.03 mmHg (SD, n = 42). The design improvement has enhanced the precision of the ART in the biomicroscope set-up to be in parity with bench test results from a set-up using perfect positioning. This indicates that off-centre positioning was no longer a major contributor to the deviations in measured IOP. The precision was well within the limits set by ISO standard for eye tonometers. Therefore, a larger in vivo study on human eyes with the ART should be performed.

  • 38.
    Hallberg, Per
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Lindén, Christina
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Lindahl, Olof A.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Bäcklund, Tomas
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Eklund, Anders
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Applanation resonance tonometry for intraocular pressure in humans2004In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 25, no 4, p. 1053-1065Article in journal (Refereed)
    Abstract [en]

    Glaucoma is a group of diseases associated with optic nerve damage and loss of visual field. The aetiology is not completely understood, but one of the major risk factors is elevated intraocular pressure (IOP). Reliable methods for measuring the IOP are therefore important. The aim of the study was to investigate the ability of the applanation resonance tonometry (ART) system, based on continuous force and area recording, to measure IOP in humans. Both the phase of initial indentation (IOPIndentation) and the phase when the sensor was removed (IOPRemoval) from the cornea were analysed. The Goldmann applanation tonometry (GAT) was used as reference method. The study included 24 healthy volunteers with normal IOP and 24 patients with elevated IOP. The correlation and standard deviation (SD) between IOPIndentation and IOPGAT was R = 0.92 (p < 0.001), SD = 3.6 mmHg, n = 104, and between IOPRemoval and IOPGAT R = 0.94 (p < 0.001), SD = 3.1 mmHg, n = 104. In conclusion, resonance sensor technology has made it possible to introduce a new multi-point method for measuring IOP, and the method is relevant for measuring IOP in humans. The study indicates that with further development towards elimination of position dependence, the ART has the potential to become a useful clinical instrument for IOP measurement.

  • 39.
    Hallberg, Per
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Santala, Kenneth
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Lindén, Christina
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Lindahl, Olof A
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Comparison of Goldmann applanation and applanation resonance tonometry in a biomicroscope-based in vitro porcine eye model2006In: J Med Eng Technol, ISSN 0309-1902, Vol. 30, no 6, p. 345-352Article in journal (Refereed)
  • 40.
    Holmberg, Miranda
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Aktivitetsmonitorering i realtid: Från cyklotron till hotcell2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report was made for the development of a web application for handling and presenting datafrom a database graphically. The data in the database comes from two sensors that are placed in twodifferent spots along a collection of three parallel pipes and read the passing of fluor-18. The reasonfor requesting the creation of this application is because of a production blockage caused by isotopesgetting stuck in the pipes and since the pipes are hard to access. In other words, this application isplanned to be used as a tool to both easier find which section the stop is in as well as to find thecause and stop the blockage before it becomes a problem.The resulting web application has one function that shows graphs of the data within a selectedtimeframe as well as a function that shows the real time data without refreshing the webpage and aselected path/pipe along with a functional view that updates the database by selected timeframe andchosen path. Because of a lack of time, the secondary goal to calculate the time of passage was notmet. It can thus be concluded that further development of the application would be beneficial foradded ease of use as a tool.

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  • 41.
    Holmgren, Madelene
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Holmlund, Petter
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Stoverud, Karen-Helene
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Health Research, SINTEF Digital, NO, Trondheim, Norway.
    Zarrinkoob, Laleh
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Wåhlin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Prediction of cerebral perfusion pressure during carotid surgery: A computational fluid dynamics approach2022In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 100, article id 105827Article in journal (Refereed)
    Abstract [en]

    Background: Maintaining cerebral perfusion pressure in the brain when a carotid artery is closed during vascular surgery is critical for avoiding intraoperative hypoperfusion and risk of ischemic stroke. Here we propose and evaluate a method based on computational fluid dynamics for predicting patient-specific cerebral perfusion pressures at carotid clamping during carotid endarterectomy.

    Methods: The study consisted of 22 patients with symptomatic carotid stenosis who underwent carotid endarterectomy (73 ± 5 years, 59–80 years, 17 men). The geometry of the circle of Willis was obtained preoperatively from computed tomography angiography and corresponding flow rates from four-dimensional flow magnetic resonance imaging. The patients were also classified as having a present or absent ipsilateral posterior communicating artery based on computed tomography angiography. The predicted mean stump pressures from computational fluid dynamics were compared with intraoperatively measured stump pressures from carotid endarterectomy.

    Findings: On group level, there was no difference between the predicted and measured stump pressures (−0.5 ± 13 mmHg, P = 0.86) and the pressures were correlated (r = 0.44, P = 0.039). Omitting two outliers, the correlation increased to r = 0.78 (P < 0.001) (−1.4 ± 8.0 mmHg, P = 0.45). Patients with a present ipsilateral posterior communicating artery (n = 8) had a higher measured stump pressure than those with an absent artery (n = 12) (P < 0.001).

    Interpretation: The stump pressure agreement indicates that the computational fluid dynamics approach was promising in predicting cerebral perfusion pressures during carotid clamping, which may prove useful in the preoperative planning of vascular interventions.

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  • 42.
    Holtermann, A
    et al.
    Human Movement Sciences Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Grönlund, Christer
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Ingebrigtsen, J
    Human Movement Sciences Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Karlsson, J Stefan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Roeleveld, K
    Human Movement Sciences Programme, Norwegian University of Science and Technology, Trondheim, Norway.
    Duration of differential activations is functionally related to fatigue prevention during low-level contractions.2010In: Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, ISSN 1873-5711, Vol. 20, no 2, p. 241-245Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the importance of duration of differential activations between the heads of the biceps brachii on local fatigue during prolonged low-level contractions. Fifteen subjects carried out isometric elbow flexion at 5% of maximal voluntary contraction (MVC) for 30 min. MVCs were performed before and at the end of the prolonged contraction. Surface electromyographic (EMG) signals were recorded from both heads of the biceps brachii. Differential activation was analysed based on the difference in EMG amplitude (activation) between electrodes situated at the two heads. Differential activations were quantified by the power spectral median frequency of the difference in activation between the heads throughout the contraction. The inverse of the median frequency was used to describe the average duration of the differential activations. The relation between average duration of the differential activations and the fatigue-induced reduction in maximal force was explored by linear regression analysis. The main finding was that the average duration of differential activation was positively associated to relative maximal force at the end of the 30 min contraction (R(2)=0.5, P<0.01). The findings of this study highlight the importance of duration of differential activations for local fatigue, and support the hypothesis that long term differential activations prevent fatigue during prolonged low-level contractions.

  • 43. Holtermann, A.
    et al.
    Grönlund, Christer
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Karlsson, J. Stefan
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Roeleveld, Karin
    Differential activation of regions within the biceps brachii muscle during fatigue2008In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 192, no 4, p. 559-567Article in journal (Refereed)
    Abstract [en]

    Aim: To examine the occurrence of repeated differential activation between the heads of the biceps brachii muscle and its relation to fatigue prevention during a submaximal contraction.

    Methods: Thirty‐nine subjects carried out an isometric contraction of elbow flexion at 25% of maximal voluntary contraction (MVC) until exhaustion. A grid of 13 by 10 electrodes was used to record surface electromyographic signals from both heads of the biceps brachii. The root‐mean‐square of signals recorded from electrodes located medially and laterally was used to analyse activation differences. Differential activation was defined as periods of 33% different activation level between the two heads of the biceps brachii muscle.

    Results: Differential muscle activation was demonstrated in 30 of 33 subjects with appropriate data quality. The frequency of differential activation increased from 4.9 to 6.6 min−1 at the end of the contractions with no change in duration of the differential activations (about 1.4 s). Moreover, the frequency of differential activation was, in general, negatively correlated with time to exhaustion.

    Conclusion: The observed differential activation between the heads of the biceps brachii can be explained by an uneven distribution of synaptic input to the motor neurone pool. The findings of this study indicate that differential activation of regions within a muscle does not prevent fatigue at a contraction level of 25% of MVC.

  • 44. Holtermann, Andreas
    et al.
    Grönlund, Christer
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Biomedical Engineering and Informatics, University Hospital, Umeå, Sweden.
    Karlsson, Stefan
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Department of Biomedical Engineering and Informatics, University Hospital, Umeå, Sweden.
    Roeleveld, Karin
    Spatial distribution of active muscle fibre characteristics in the upper trapezius muscle and its dependency on contraction level and duration2008In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 18, no 3, p. 372-381Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to provide direct in vivo information of the physiological and structural characteristics of active muscle fibres from a large part of the upper trapezius muscle. Two-dimensional (2-D) multi-channel surface electromyography recordings were used, with 13 × 10 electrodes covering 6 × 4.5 cm of the skin’s surface. A previously developed method was applied to detect individual propagating motor unit action potentials and to estimate their corresponding muscle fibre conduction velocity (MFCV) and muscle fibre orientation (MFO). Using these estimates, spatial distributions of MFCV and MFO were examined for five male subjects performing isometric shoulder elevation at different force levels. The main results were: (1) the general relationship between MFCV and force generation was non-systematic, with a positive relationship at the inferior part of the muscle, (2) the spatial distribution of MFCV at different force levels and fatigue was inhomogeneous and (3) the MFO was slightly different (6°) of the muscle fibres with origin superior compared to inferior to the C7 vertebra. These findings provide new information of the MFO of contracting muscle fibres and knowledge of the physiological characteristics of a large part of the upper trapezius muscle that previously was based on observations from human cadavers only.

  • 45.
    Hu, Xiao-Lei
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Jonzén, Karolina
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Lindahl, Olof A
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Marcus
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Norström, Fredrik
    Umeå University, Faculty of Medicine, Department of Epidemiology and Global Health.
    Lundström, Erik
    Department of Medical Sciences, Neurology, Akademiska Sjukhuset, Uppsala University, Uppsala, Sweden.
    Stibrant Sunnerhagen, Katharina
    Department of Neuroscience and Physiology, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden.
    Digital Graphic Follow-up Tool (Rehabkompassen) for Identifying Rehabilitation Needs among People after Stroke: Randomized Clinical Feasibility Study2022In: JMIR Human Factors, E-ISSN 2292-9495, Vol. 9, no 3, article id e38704Article in journal (Refereed)
    Abstract [en]

    Background: Stroke is a leading cause of disability among adults, with heavy social and economic burden worldwide. A cost-effective solution is urgently needed to facilitate the identification of individual rehabilitation needs and thereby provide tailored rehabilitations to reduce disability among people who have had a stroke. A novel digital graphic follow-up tool Rehabkompassen has recently been developed to facilitate capturing the multidimensional rehabilitation needs of people who have had a stroke.

    Objective: The aim of this study was to evaluate the feasibility and acceptability of conducting a definitive trial to evaluate Rehabkompassen as a digital follow-up tool among people who have had a stroke in outpatient clinical settings.

    Methods: This pilot study of Rehabkompassen was a parallel, open-label, 2-arm prospective, proof-of-concept randomized controlled trial (RCT) with an allocation ratio of 1:1 in a single outpatient clinic. Patients who have had a stroke within the 3 previous months, aged ≥18 years, and living in the community were included. The trial compared usual outpatient visits with Rehabkompassen (intervention group) and without Rehabkompassen (control group) at the 3-month follow-up as well as usual outpatient visit with Rehabkompassen at the 12-month follow-up. Information on the recruitment rate, delivery, and uptake of Rehabkompassen; assessment and outcome measures completion rates; the frequency of withdrawals; the loss of follow-up; and satisfaction scores were obtained. The key outcomes were evaluated in both groups.

    Results: In total, 28 patients (14 control, 14 Rehabkompassen) participated in this study, with 100 patients screened. The overall recruitment rate was 28% (28/100). Retention in the trial was 86% (24/28) at the 12-month follow-up. All participants used the tool as planned during their follow-ups, which provided a 100% (24/24) task completion rate of using Rehabkompassen and suggested excellent feasibility. Both patient- and physician-participants reported satisfaction with the instrument (19/24, 79% and 2/2, 100%, respectively). In all, 2 (N=2, 100%) physicians and 18 (N=24, 75%) patients were willing to use the tool in the future. Furthermore, modified Rankin Scale as the primary outcome and various stroke impacts as secondary outcomes were both successfully collected and compared in this study.

    Conclusions: This study demonstrated the high feasibility and adherence of the study protocol as well as the high acceptability of Rehabkompassen among patients who have had a stroke and physicians in an outpatient setting in comparison to the predefined criterion. The information collected in this feasibility study combined with the amendments of the study protocol may improve the future definitive RCT. The results of this trial support the feasibility and acceptability of conducting a large definitive RCT.

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  • 46.
    Israelsson, Hanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Carlberg, Bo
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Wikkelsö, Carsten
    Laurell, Katarina
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Kahlon, Babar
    Leijon, Göran
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Vascular risk factors contribute to idiopathic normal pressure hydrocephalus: the INPH-CRasH StudyManuscript (preprint) (Other academic)
    Abstract [en]

    Objective

    The objective was to determine the complete modern vascular risk factor (VRF) profile of idiopathic normal pressure hydrocephalus (INPH) using a large sample of representative INPH-patients and population-based controls, in order to confirm the impact of vascular disease on INPH pathophysiology.

     

    Methods

    All shunted INPH-patients in Sweden 2008-2010 were compared to age- and gender-matched population-based controls. Inclusion criteria: 60-85 years and mini mental state estimation ³23. The ten most important modern VRFs as well as cerebrovascular and peripheral vascular disease were prospectively assessed through blood samples, by-protocol clinical examinations and standardized questionnaires. Investigated VRFs: hypertension, hyperlipidemia, diabetes, obesity, psychosocial factors, smoking, diet, alcohol intake, cardiac disease and, physical activity.

     

    Results

    After exclusion, 176 INPH-patients and 368 controls participated. Using multivariable logistic regression, hyperlipidemia (OR: 2.380, 95%CI: 1.434-3.950), diabetes (OR: 2.169, 95%CI: 1.195-3.938), obesity (OR: 5.428, 95%CI: 2.502-11.772) and, psychosocial factors (OR: 5.343, 95%CI: 3.219-8.868) were independently associated with INPH. Hypertension, physical inactivity, cerebrovascular and peripheral vascular disease were overrepresented in INPH, although not independently. The protective factors: moderate alcohol intake and physical activity were overrepresented among the controls. The population attributable risk percentage was 24%.

     

    Conclusions

    Our findings confirm that INPH-patients have a more dangerous VRF-profile and lack the protective factors present in the population. Almost one quarter of INPH could be explained by VRF, suggesting that INPH possibly may be a subgroup of vascular dementia. Targeted interventions against modifiable VRF are likely to have beneficial effects in INPH.

  • 47.
    Israelsson, Hanna
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Carlberg, Bo
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wikkelsö, Carsten
    Laurell, Katarina
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Kahlon, Babar
    Leijon, Göran
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Vascular risk factors in INPH A prospective case- control study (the INPH-CRasH study)2017In: Neurology, ISSN 0028-3878, E-ISSN 1526-632X, Vol. 88, no 6, p. 577-585Article in journal (Refereed)
    Abstract [en]

    Objective: To assess the complete vascular risk factor (VRF) profile of idiopathic normal pressure hydrocephalus (INPH) using a large sample of representative patients with INPH and populationbased controls to determine the extent to which vascular disease influences INPH pathophysiology. Methods: All patients with INPH who underwent shunting in Sweden in 2008-2010 were compared to age-and sex-matched population-based controls. Inclusion criteria were age 60-85 years and no dementia. The 10 most important VRFs and cerebrovascular and peripheral vascular disease were prospectively assessed using blood samples, clinical examinations, and standardized questionnaires. Assessed VRFs were hypertension, hyperlipidemia, diabetes, obesity, psychosocial factors, smoking habits, diet, alcohol intake, cardiac disease, and physical activity. Results: In total, 176 patients with INPH and 368 controls participated. Multivariable logistic regression analysis indicated that hyperlipidemia (odds ratio [OR] 2.380; 95% confidence interval [CI] 1.434-3.950), diabetes (OR 2.169; 95% CI 1.195-3.938), obesity (OR 5.428; 95% CI 2.502-11.772), and psychosocial factors (OR 5.343; 95% CI 3.219-8.868) were independently associated with INPH. Hypertension, physical inactivity, and cerebrovascular and peripheral vascular disease were also overrepresented in INPH. Moderate alcohol intake and physical activity were overrepresented among the controls. The population-attributable risk percentage was 24%. Conclusions: Our findings confirm that patients with INPH have more VRFs and lack the protective factors present in the general population. Almost 25% of cases of INPH may be explained by VRFs. This suggests that INPH may be a subtype of vascular dementia. Targeted interventions against modifiable VRFs are likely to have beneficial effects on INPH.

  • 48.
    Israelsson, Hanna
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.
    Cerebrospinal Fluid Shunting Improves Long-Term Quality of Life in Idiopathic Normal Pressure Hydrocephalus2020In: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 86, no 4, p. 574-582Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The short- and long-term impact of cerebrospinal fluid shunting on quality of life (QoL) in idiopathic normal pressure hydrocephalus (INPH) is poorly understood.

    OBJECTIVE: To investigate QoL in shunted INPH patients compared to the population and to investigate which factors influence QoL in INPH.

    METHODS: INPH patients consecutively shunted in Sweden during 2008-2010 were scrutinized. Population-based controls were age- and sex-matched to the patients. Included participants were the following: 176 INPH patients and 368 controls. QoL was assessed using the EuroQol 5-dimension 5-level (EQ5D5L) instrument, which measures overall QoL and health status in 5 dimensions. Independency (accommodation and/or need for in-home care) and comorbidities were assessed. Patients were followed up 6-45 mo after surgery (mean follow-up time: 21 mo).

    RESULTS: Shunting improved QoL (P < .001) and health status in all dimensions (P < .005). Shunted INPH patients had lower QoL than controls (P < .001). The patients' health status in mobility, self-care, daily activities, and anxiety/depression was worse than the controls both before and after surgery (P < .001). The main predictors of low QoL in INPH were symptoms of depression (P < .001) and severity of gait disturbance (P = .001). Fewer INPH patients than controls lived independently (45% vs 85%, P < .001). Time after shunting had no influence on QoL.

    CONCLUSION: QoL remains improved in shunted INPH patients at a mean follow-up time of 21 mo, but the patients do not reach the same QoL as the population. Symptoms of depression and severity of gait disturbance are the strongest predictors of low QoL in INPH.

  • 49.
    Israelsson, Hanna
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    CSF shunting improves long-term quality of life in idiopathic normal pressure hydrocephalus: the INPH-CRasH StudyManuscript (preprint) (Other academic)
    Abstract [en]

    Introduction

    Measurements of quality of life (QoL) are important when evaluating a surgical method. However, QoL after shunting in idiopathic normal pressure hydrocephalus (INPH) is seldom assessed. The objective of this study was to assess QoL in a large cohort of shunted INPH patients, compared to the population, and investigate which factors influence QoL in INPH.

     

    Methods

    All INPH patients shunted in Sweden 2008-2010 were scrutinized. Population-based controls were age- and gender-matched to the patients. One hundred and seventy-six INPH patients and 368 controls were included. QoL was assessed using the EQ5D5L instrument, measuring overall QoL and health status in five dimensions. Independency, measured by accommodation and need for in-home care, and comorbidities were assessed. Patients were followed up 6-45 months after surgery (mean follow-up time: 21 months).

     

    Results

    Shunted INPH patients had lower QoL than controls (p<0.001). The patients’ health status in mobility, self-care, daily activities, and anxiety/depression was worse than the controls both before and after surgery (p<0.001). Shunting improved QoL (p<0.001) and health status in all dimensions (p<0.005). The main predictors of low QoL in INPH were depression (p<0.001) and severity of gait disturbance (p=0.001). Fewer INPH patients than controls lived independently (45% vs 85%, p<0.001) Time after shunting had no influence on QoL.

     

    Interpretation

    Improvement in QoL after shunting in INPH is long lasting, but shunted INPH patients do not reach the same level of QoL as the population. Depression and severity of gait disturbance are the strongest predictors of low QoL in INPH. 

  • 50.
    Jacobsson, Johan
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Qvarlander, Sara
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Comparison of the CSF dynamics between patients with idiopathic normal pressure hydrocephalus and healthy volunteers2019In: Journal of Neurosurgery, ISSN 0022-3085, E-ISSN 1933-0693, Vol. 131, no 4, p. 1018-1023Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Intracranial pressure (ICP), outflow resistance (Rout), and amplitude of cardiac-related ICP pulsations (AMPs) are established parameters to describe the CSF hydrodynamic system and are assumed, but not confirmed, to be disturbed in idiopathic normal pressure hydrocephalus (INPH). The aim of this study was to compare the CSF hydrodynamic profile between patients with INPH and healthy volunteers.

    METHODS: Sixty-two consecutive INPH patients (mean age 74 years) and 40 healthy volunteers (mean age 70 years) were included. Diagnosis was made by two independent neurologists who assessed patients’ history, neurological status, and MRI studies. A CSF dynamic investigation through the lumbar route was performed: ICP and other CSF dynamic variables were blinded to the neurologists during the diagnostic process and were not used for establishing the diagnosis of INPH.

    RESULTS: Rout was significantly higher in INPH (Rout 17.1 vs 11.1; p < 0.001), though a substantial number of INPH subjects had normal Rout. There were no differences between INPH patients and controls regarding ICP (mean 11.5 mm Hg). At resting pressure, there was a trend that AMP in INPH was increased (2.4 vs 2.0 mm Hg; p = 0.109). The relationship between AMP and ICP was that they shared the same slope, but the curve was significantly shifted to the left for INPH (reduced P0 [p < 0.05]; i.e., higher AMP for the same ICP).

    CONCLUSIONS: This study established that the CSF dynamic profile of INPH deviates from that of healthy volunteers and that INPH should thus be regarded as a disease in which intracranial hydrodynamics are part of the pathophysiology.

    Clinical trial registration no.: NCT01188382 (clinicaltrials.gov)

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