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  • 301.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Bach Andersen, Jørgen
    Section on Antennas, Propagation and Radio Networking, Department of Electronic Systems, Faculty of Engineering and Science, Aalborg University , Denmark.
    Frølund Pedersen, Gert
    Section on Antennas, Propagation and Radio Networking, Department of Electronic Systems, Faculty of Engineering and Science, Aalborg University , Denmark.
    Is there any exposure from a mobile phone in stand-by mode?2012Inngår i: Electromagnetic Biology and Medicine, ISSN 1536-8378, E-ISSN 1536-8386, Vol. 31, nr 1, s. 52-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several studies have been using a GSM mobile phone in stand-by mode as the source for exposure, and they claimed that this caused effects on for instance sleep and testicular function. In stand-by mode the phone is only active in periodic location updates, and this occurs with a frequency set by the net operator. Typical updates occur with 2-5 h in between, and between these updates the phone is to be considered as a passive radio receiver with no microwave emission. Thus, the exposure in stand-by mode can be considered negligible.

    Fulltekst (pdf)
    fulltext
  • 302.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Bergling, Roland
    Hörnsten, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Heart Rate Variability and Magnetic Field Exposure Among Train Engine Drivers: A Pilot Study2021Inngår i: Bioelectromagnetics, ISSN 0197-8462, E-ISSN 1521-186X, Vol. 43, nr 3, s. 259-264Artikkel i tidsskrift (Fagfellevurdert)
  • 303.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Hand, Jeff
    Hietanen, Maila
    Gowland, Penny
    Karpowicz, Jolanta
    Keevil, Stephen
    Lagroye, Isabelle
    van Rongen, Eric
    Scarfi, Maria Rosaria
    Wilén, Jonna
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Exposure classification of MRI workers in epidemiological studies2013Inngår i: Bioelectromagnetics, ISSN 0197-8462, E-ISSN 1521-186X, Vol. 34, nr 1, s. 81-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We estimate that there are about 100,000 workers from different disciplines, such as radiographers, nurses, anesthetists, technicians, engineers, etc., who can be exposed to substantial electromagnetic fields (compared to normal background levels) around magnetic resonance imaging (MRI) scanners. There is a need for well-designed epidemiological studies of MRI workers but since the exposure from MRI equipment is a very complex mixture of static magnetic fields, switched gradient magnetic fields, and radiofrequency electromagnetic fields (RF EMF), it is necessary to discuss how to assess the exposure in epidemiological studies. As an alternative to the use of job title as a proxy of exposure, we propose an exposure categorization for the different professions working with MRI equipment. Specifically, we propose defining exposure in three categories, depending on whether people are exposed to only the static field, to the static plus switched gradient fields or to the static plus switched gradient plus RF fields, as a basis for exposure assessment in epidemiological studies.

  • 304.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinsk fakultet, Strålningsvetenskaper, Radiofysik.
    Hardell, Lennart
    Carlberg, Michael
    Pooled analysis of two Swedish case-control studies on the use of mobile and cordless telephones and the risk of brain tumours diagnosed during 1997-2003.2007Inngår i: International Journal of Occupational Safety and Ergonomics, ISSN 1080-3548, Vol. 13, nr 1, s. 63-71Artikkel i tidsskrift (Fagfellevurdert)
  • 305.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Johnsson, Anders
    Hardell, Lennart
    Robotic Lawn Mower: A New Source for Domestic Magnetic Field Exposure2021Inngår i: Bioelectromagnetics, ISSN 0197-8462, E-ISSN 1521-186X, Vol. 42, nr 1, s. 95-99Artikkel i tidsskrift (Fagfellevurdert)
  • 306.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Lundström, Ronnie
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wilén, Jonna
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Non-Ionizing Radiation in Swedish Health CareExposure and Safety Aspects2019Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 16, nr 7, artikkel-id 1186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main aim of the study was to identify and describe methods using non-ionizing radiation (NIR) such as electromagnetic fields (EMF) and optical radiation in Swedish health care. By examining anticipated exposure levels and by identifying possible health hazards we also aimed to recognize knowledge gaps in the field. NIR is mainly used in health care for diagnosis and therapy. Three applications were identified where acute effects cannot be ruled out: magnetic resonance imaging (MRI), transcranial magnetic stimulation (TMS) and electrosurgery. When using optical radiation, such as class 3 and 4 lasers for therapy or surgical procedures and ultra-violet light for therapy, acute effects such as unintentional burns, photo reactions, erythema and effects on the eyes need to be avoided. There is a need for more knowledge regarding long-term effects of MRI as well as on the combination of different NIR exposures. Based on literature and after consulting staff we conclude that the health care professionals' knowledge about the risks and safety measures should be improved and that there is a need for clear, evidence-based information from reliable sources, and it should be obvious to the user which source to address.

    Fulltekst (pdf)
    fulltext
  • 307.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Mattsson, Mats-Olof
    Dose and exposure in bioelectromagnetics2017Inngår i: Dosimetry in bioelectromagnetics / [ed] Marko Markov, Boca Raton: CRC Press , 2017, s. 101-117Kapittel i bok, del av antologi (Fagfellevurdert)
  • 308.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Mattsson, Mats-Olof
    Örebro University, Sweden; Seibersdorf, Austria.
    ELF noise fields: a review2010Inngår i: Electromagnetic Biology and Medicine, ISSN 1536-8378, E-ISSN 1536-8386, Vol. 29, nr 3, s. 72-97Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The debate as to whether low-level electromagnetic fields can affect biological systems and in the long term cause health effects has been going on for a long time. Yet the interaction of weak electromagnetic fields (EMF) with living cells, undoubtedly a most important phenomenon, is still not well understood. The exact mechanisms by which the effects are produced have not been identified. Furthermore, it is not possible to clearly define which aspects of an EMF exposure that constitute the "dose." One of the groups that contributed to solving this problem is the Bioelectromagnetics group at Catholic University of America (CUA), Washington, D. C. Their work has been devoted to investigating the physical parameters that are needed to obtain an effect of EMF exposure on biological systems, and also how to inhibit the effect. This is a review of their work on bioeffects caused by low-level EMF, their dependence on coherence time, constancy, spatial averaging, and also how the effects can be modified by an applied ELF noise magnetic field. The group has been using early chick embryos, and L929 and Daudi cells as their main experimental systems. The review also covers the work of other groups on low-level effects and the inhibition of the effects with an applied noise field. The group at CUA has shown that biological effects can be found after exposure to low-level ELF and RF electromagnetic fields, and when effects are observed, applying an ELF magnetic noise field inhibits the effects. Also, other research groups have tried to replicate the studies from the CUA group, or to apply EMF noise to suppress EMF-induced effects. Replications of the CUA effects have not always been successful. However, in all cases where the noise field has been applied to prevent an observed effect, it has been successful in eliminating the effect.

  • 309.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Mattsson, Mats-Olof
    SciProof International AB, Östersund, Sweden; Institute of Advanced Studies, Strömstad Academy, Strömstad, Sweden.
    Jeschke, Peter
    Federal Institute for Occupational Safety and Health, Dortmund, Germany.
    Israel, Michel
    National Centre of Public Health and Analyses, Sofia, Bulgaria.
    Ivanova, Mihaela
    National Centre of Public Health and Analyses, Sofia, Bulgaria.
    Shalamanova, Tsvetelina
    National Centre of Public Health and Analyses, Sofia, Bulgaria.
    Occupational exposure to electromagnetic fields: different from general public exposure and laboratory studies2023Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 20, nr 16, artikkel-id 6552Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The designs of in vivo, in vitro and in silico studies do not adequately reflect the characteristics of long-term occupational EMF exposure; the higher exposure levels permitted for employees are nevertheless extrapolated on this basis. Epidemiological studies consider occupational exposure only in a very general way, if at all. There is a lack of detailed descriptive data on long-term occupational exposure over the duration of the working life. Most studies reflect exposure characteristics of the general population, exposures which are long-term, but at a comparably low level. Occupational exposure is often intermittent with high peak power followed by periods with no exposure. Furthermore, the EU EMF-Directive 2013/35/EU states a demand for occupational health surveillance, the outcome of which would be of great help to epidemiologists studying the health effects of EMF exposure. This paper thus aims to outline and specify differences between public and occupational exposure and to increase the understanding of specific aspects of occupational exposure which are important for long-term health considerations. This could lead to a future protection concept against possible hazards based on adequate descriptions of long-term exposures and also include supplementary descriptive features such as a “reset time” of biological systems and accurate dose quantities.

    Fulltekst (pdf)
    fulltext
  • 310.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Møllerløkken, Ole Jacob
    Occupational Exposure to Magnetic Field inTranscranial Magnetic Stimulation Treatment2018Inngår i: Transcranial Magnetic Stimulation in Neuropsychiatry / [ed] Ustohal, Libor, IntechOpen , 2018, s. 143-149Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Transcranial magnetic stimulation (TMS) is used both as a diagnostic instrument and for therapy, available only at some psychiatric clinics for treatment of depression and at clinical neurophysiology where TMS is used for diagnosis of nerve damage. The Swedish National Board of Health and Welfare issued a referral edition about the use of repetitive TMS as an alternative treatment for depression. This may lead to a major increase in the application of TMS to treat depression. TMS is based on induction of an electric (E) field inside the brain by application of an external magnetic field with rapid rise and fall time. The E field in the brain has been calculated when different coils were used for the treatment. The reported E fields are of the order of tens to hundreds of volts per meter and the induced current density is estimated at tens of A/m2. This field can depolarize neurons or modulate cortical excitability by selecting the appropriate parameters for stimulation and the duration of the treatment session. The mechanisms of action of neurostimulation still remain incompletely understood.

    Fulltekst (pdf)
    fulltext
  • 311.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wilén, Jonna
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Occupational exposure in wireless communication2009Inngår i: Advances in electromagnetic fields in living systems: Vol 5, Health effects of cell phone radiation / [ed] James C Lin, Heidelberg: Springer-Verlag New York, 2009, s. 199-219Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Today we are exposed to electromagnetic fields from the use of wireless communication devices almost everywhere. However, occupational exposure where there is a possibility to exceed the international guidelines occurs only in work very near mobile phone base stations, and this exposure can easily be dealt with in practice in the form of instructions and administrative measures. All other devices produce exposure well below present guidelines. This low-level exposure has been discussed from a health perspective, and in this paper the exposure from sources such as mobile phones, cordless phones, WiMax, WLAN and base station antennas is discussed. The problem of exposure assessment for epidemiological studies is also dealt with in a general manner.

  • 312.
    Hansson Mild, Kjell
    et al.
    Umeå universitet, Medicinsk fakultet, Strålningsvetenskaper, Radiofysik.
    Wilén, Jonna
    Umeå universitet, Medicinsk fakultet, Strålningsvetenskaper, Radiofysik.
    Mattsson, Mats-Olof
    Simko, Myrtill
    Background ELF magnetic fields in incubators: A factor of importance in cell culture work.2009Inngår i: Cell biology international, ISSN 1095-8355, Vol. 33, s. 755-757Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Extremely low frequency (ELF) magnetic fields in cell culture incubators have been measured. Values of the order of tens of muT were found which is in sharp contrast to the values found in our normal environment (0.05-0.1muT). There are numerous examples of biological effects found after exposure to MF at these levels, such as changes in gene expression, blocked cell differentiation, inhibition of the effect of tamoxifen, effects on chick embryo development, etc. We therefore recommend that people working with cell culture incubators check for the background magnetic field and take this into account in performing their experiments, since this could be an unrecognised factor of importance contributing to the variability in the results from work with cell cultures.

  • 313.
    Hansson, William
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Birgander, Richard
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Cerebral Microbleeds-Long-Term Outcome After Cerebrospinal Fluid Shunting in Idiopathic Normal Pressure Hydrocephalus2023Inngår i: Neurosurgery, ISSN 0148-396X, E-ISSN 1524-4040, Vol. 93, nr 2, s. 300-308Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Cerebral microbleeds (CMBs) are common in idiopathic normal pressure hydrocephalus (INPH) and have been suggested as radiological markers of a brain prone to bleeding. The presence of CMBs might be relevant when selecting patients for shunt surgery.

    OBJECTIVE: To evaluate whether CMBs increases long-term risk of hemorrhagic complications and mortality or affects outcomes after cerebrospinal fluid shunt surgery in a cohort of patients with INPH.

    METHODS: One hundred and forty nine shunted patients with INPH (mean age, 73 years) were investigated with MRI (T2* or susceptibility-weighted imaging sequences) preoperatively. CMBs were scored with the Microbleed Anatomic Rating Scale. Patients were observed for a mean of 6.5 years (range 2 weeks to 13 years) after surgery. Hemorrhagic events and death were noted. Improvement in gait was evaluated 3 to 6 months after surgery.

    RESULTS: At baseline, 74 patients (50%) had CMBs. During follow-up, 7 patients (5%) suffered a hemorrhagic stroke and 43 (29%) suffered a subdural hematoma/hygroma with a median time from surgery of 30.2 months (IQR 50). Overall, having CMBs was not associated with suffering a subdural hematoma/hygroma or hemorrhagic stroke during follow-up with 1 exception that an extensive degree of CMBs (≥50 CMB) was more common in patients suffering a hemorrhagic stroke ( P = .03). CMBs were associated with increased mortality ( P = .02, Kaplan-Meier, log-rank test). The presence of CMBs did not affect gait outcome ( P = .28).

    CONCLUSION: CMBs were associated with hemorrhagic stroke and mortality. CMBs do not seem to reduce the possibility of gait improvement after shunt surgery or contribute to the risk of hemorrhagic complications regarding subdural hematoma or hygroma.

  • 314. Hardell, Lennart
    et al.
    Carlberg, Michael
    Hansson Mild, Kjell
    Umeå universitet, Medicinsk fakultet, Strålningsvetenskaper, Radiofysik.
    Epidemiological evidence for an association between use of wireless phones and tumor diseases.2009Inngår i: Pathophysiology : the official journal of the International Society for Pathophysiology / ISP, ISSN 0928-4680, Vol. 16, nr 2-3, s. 113-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During recent years there has been increasing public concern on potential cancer risks from microwave emissions from wireless phones. We evaluated the scientific evidence for long-term mobile phone use and the association with certain tumors in case-control studies, mostly from the Hardell group in Sweden and the Interphone study group. Regarding brain tumors the meta-analysis yielded for glioma odds ratio (OR)=1.0, 95% confidence interval (CI)=0.9-1.1. OR increased to 1.3, 95% CI=1.1-1.6 with 10 year latency period, with highest risk for ipsilateral exposure (same side as the tumor localisation), OR=1.9, 95% CI=1.4-2.4, lower for contralateral exposure (opposite side) OR=1.2, 95% CI=0.9-1.7. Regarding acoustic neuroma OR=1.0, 95% CI=0.8-1.1 was calculated increasing to OR=1.3, 95% CI=0.97-1.9 with 10 year latency period. For ipsilateral exposure OR=1.6, 95% CI=1.1-2.4, and for contralateral exposure OR=1.2, 95% CI=0.8-1.9 were found. Regarding meningioma no consistent pattern of an increased risk was found. Concerning age, highest risk was found in the age group <20 years at time of first use of wireless phones in the studies from the Hardell group. For salivary gland tumors, non-Hodgkin lymphoma and testicular cancer no consistent pattern of an association with use of wireless phones was found. One study on uveal melanoma yielded for probable/certain mobile phone use OR=4.2, 95% CI=1.2-14.5. One study on intratemporal facial nerve tumor was not possible to evaluate due to methodological shortcomings. In summary our review yielded a consistent pattern of an increased risk for glioma and acoustic neuroma after >10 year mobile phone use. We conclude that current standard for exposure to microwaves during mobile phone use is not safe for long-term exposure and needs to be revised.

  • 315. Hardell, Lennart
    et al.
    Carlberg, Michael
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Methodological aspects of epidemiological studies on the use of mobile phones and their association with brain tumors2008Inngår i: The Open Environmental Journal, ISSN 1874-2335, Vol. 2, s. 54-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Our case-control studies were the first to report an association between the use of mobile or cordless phonesand brain tumors; glioma and acoustic neuroma. Criticism of these results has been based partly on results from the Interphonestudies conducted under the auspice of the International Agency for Research on Cancer (IARC). Here, we comparestudy design and epidemiological methods used in our studies and the Interphone studies. We conclude that while ourresults appear sound and reliable, several of the Interphone findings display differential misclassification of exposure dueto observational and recall bias, for example, following low participation rates in both cases and controls and bed-sidecomputer guided interviews of cases rather than blinded interviews of cases and controls. However, as we have presentedelsewhere, there seems to be a consistent pattern of an association between mobile phone use and ipsilateral glioma andacoustic neuroma using > 10 years latency period.

  • 316.
    Hardell, Lennart
    et al.
    Department of Oncology, University Hospital, Örebro.
    Carlberg, Michael
    Department of Oncology, University Hospital, Örebro.
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Mobile phone use and the risk for malignant brain tumors: A case-control study on deceased cases and controls2010Inngår i: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208, Vol. 35, nr 2, s. 109-114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated the use of mobile or cordless phones and the risk for malignant brain tumors in a group of deceased cases. Most previous studies have either left out deceased cases of brain tumors or matched them to living controls and therefore a study matching deceased cases to deceased controls is warranted. Recall error is one issue since it has been claimed that increased risks reported in some studies could be due to cases blaming mobile phones as a cause of the disease. This should be of less importance for deceased cases and if cancer controls are used. In this study brain tumor cases aged 20-80 years diagnosed during 1997-2003 that had died before inclusion in our previous studies on the same topic were included. Two control groups were used: one with controls that had died from another type of cancer than brain tumor and one with controls that had died from other diseases. Exposure was assessed by a questionnaire sent to the next-of-kin for both cases and controls. Replies were obtained for 346 (75%) cases, 343 (74%) cancer controls and 276 (60%) controls with other diseases. Use of mobile phones gave an increased risk, highest in the >10 years' latency group yielding odds ratio (OR) = 2.4, and 95% confidence interval (CI) = 1.4-4.1. The risk increased with cumulative number of lifetime hours for use, and was highest in the >2,000 h group (OR = 3.4, 95% CI = 1.6-7.1). No clear association was found for use of cordless phones, although OR = 1.7, 95% CI = 0.8-3.4 was found in the group with >2,000 h of cumulative use. This investigation confirmed our previous results of an association between mobile phone use and malignant brain tumors.

  • 317. Hardell, Lennart
    et al.
    Carlberg, Michael
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Pooled analysis of case-control studies on malignant brain tumours and the use of mobile and cordless phones including living and deceased subjects2011Inngår i: International Journal of Oncology, ISSN 1019-6439, E-ISSN 1791-2423, Vol. 38, nr 5, s. 1465-1474Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We studied the association between use of mobile and cordless phones and malignant brain tumours. Pooled analysis was performed of two case-control studies on patients with malignant brain tumours diagnosed during 1997-2003 and matched controls alive at the time of study inclusion and one case-control study on deceased patients and controls diagnosed during the same time period. Cases and controls or relatives to deceased subjects were interviewed using a structured questionnaire. Replies were obtained for 1,251 (85%) cases and 2,438 (84%) controls. The risk increased with latency period and cumulative use in hours for both mobile and cordless phones. Highest risk was found for the most common type of glioma, astrocytoma, yielding in the >10 year latency group for mobile phone use odds ratio (OR) = 2.7, 95% confidence interval (CI) = 1.9-3.7 and cordless phone use OR = 1.8, 95% CI = 1.2-2.9. In a separate analysis, these phone types were independent risk factors for glioma. The risk for astrocytoma was highest in the group with first use of a wireless phone before the age of 20; mobile phone use OR = 4.9, 95% CI = 2.2-11, cordless phone use OR = 3.9, 95% CI = 1.7-8.7. In conclusion, an increased risk was found for glioma and use of mobile or cordless phone. The risk increased with latency time and cumulative use in hours and was highest in subjects with first use before the age of 20.

  • 318. Hardell, Lennart
    et al.
    Carlberg, Michael
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Re-analysis of risk for glioma in relation to mobile telephone use: comparison with the results of the Interphone international case-control study2011Inngår i: International Journal of Epidemiology, ISSN 0300-5771, E-ISSN 1464-3685, Vol. 40, nr 4, s. 1126-1128Artikkel i tidsskrift (Fagfellevurdert)
  • 319. Hardell, Lennart
    et al.
    Carlberg, Michael
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eriksson, Mikael
    Case-control study on the use of mobile and cordless phones and the risk for malignant melanoma in the head and neck region2011Inngår i: Pathophysiology : the official journal of the International Society for Pathophysiology / ISP, ISSN 0928-4680, Vol. 18, nr 4, s. 325-333Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The incidence of cutaneous malignant melanoma has increased during the last decades in Sweden as in many other countries. Besides of ultraviolet radiation and constitutional factors such as light-sensitive skin and poor ability to tan few risk factors are established. Some studies indicate that electromagnetic fields might be of concern. In this case-control study we assessed use of mobile and cordless phones in 347 cases with melanoma in the head and neck region and 1184 controls. These subjects constituted 82% and 80%, respectively, that answered the questionnaire. Overall no increased risk was found. However, in the most exposed area; temporal, cheek and ear, cumulative use >365h of mobile phone yielded in the >1-5-year latency group odds ratio (OR)=2.1, 95% confidence interval (CI)=0.7-6.1 and cordless phone use gave OR=2.1, 95% CI=1.1-3.8. Highest OR was calculated for first use of mobile or cordless phone before the age of 20 years regardless of anatomical localisation in the head and neck region. No interaction was found with established risk factors such as red, medium blond or fair hair colour, blue eyes, skin type I or II (never or sometimes tanned), severe sunburns as teenager or heredity. The results must be interpreted with caution due to low numbers and potential methodological shortcomings in a case-control study. However, the findings might be consistent with a late carcinogenic effect from microwaves, i.e. tumour promotion, but need to be confirmed.

  • 320. Hardell, Lennart
    et al.
    Carlberg, Michael
    Soderqvist, Fredrik
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Case-control study of the association between malignant brain tumours diagnosed between 2007 and 2009 and mobile and cordless phone use2013Inngår i: International Journal of Oncology, ISSN 1019-6439, E-ISSN 1791-2423, Vol. 43, nr 6, s. 1833-1845Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous studies have shown a consistent association between long-term use of mobile and cordless phones and glioma and acoustic neuroma, but not for meningioma. When used these phones emit radiofrequency electromagnetic fields (RF-EMFs) and the brain is the main target organ for the hand-held phone. The International Agency for Research on Cancer (IARC) classified in May, 2011 RF-EMF as a group 2B, i.e. a possible' human carcinogen. The aim of this study was to further explore the relationship between especially long-term (>10 years) use of wireless phones and the development of malignant brain tumours. We conducted a new case-control study of brain tumour cases of both genders aged 18-75 years and diagnosed during 2007-2009. One population-based control matched on gender and age (within 5 years) was used to each case. Here, we report on malignant cases including all available controls. Exposures on e.g. use of mobile phones and cordless phones were assessed by a self-administered questionnaire. Unconditional logistic regression analysis was performed, adjusting for age, gender, year of diagnosis and socio-economic index using the whole control sample. Of the cases with a malignant brain tumour, 87% (n=593) participated, and 85% (n=1,368) of controls in the whole study answered the questionnaire. The odds ratio (OR) for mobile phone use of the analogue type was 1.8, 95% confidence interval (CI)=1.04-3.3, increasing with >25 years of latency (time since first exposure) to an OR=3.3, 95% CI=1.6-6.9. Digital 2G mobile phone use rendered an OR=1.6, 95% CI=0.996-2.7, increasing with latency >15-20 years to an OR=2.1, 95% CI=1.2-3.6. The results for cordless phone use were OR=1.7, 95% CI=1.1-2.9, and, for latency of 15-20 years, the OR=2.1, 95% CI=1.2-3.8. Few participants had used a cordless phone for >20-25 years. Digital type of wireless phones (2G and 3G mobile phones, cordless phones) gave increased risk with latency >1-5 years, then a lower risk in the following latency groups, but again increasing risk with latency >15-20 years. Ipsilateral use resulted in a higher risk than contralateral mobile and cordless phone use. Higher ORs were calculated for tumours in the temporal and overlapping lobes. Using the meningioma cases in the same study as reference entity gave somewhat higher ORs indicating that the results were unlikely to be explained by recall or observational bias. This study confirmed previous results of an association between mobile and cordless phone use and malignant brain tumours. These findings provide support for the hypothesis that RF-EMFs play a role both in the initiation and promotion stages of carcinogenesis.

    Fulltekst (pdf)
    fulltext
  • 321. Hardell, Lennart
    et al.
    Carlberg, Michael
    Soderqvist, Fredrik
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Mobile Phones and Cancer Next Steps2014Inngår i: Epidemiology, ISSN 1044-3983, E-ISSN 1531-5487, Vol. 25, nr 4, s. 617-618Artikkel i tidsskrift (Fagfellevurdert)
  • 322. Hardell, Lennart
    et al.
    Carlberg, Michael
    Söderqvist, Fredrik
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Meta-analysis of long-term mobile phone use and the association with brain tumours.2008Inngår i: Int J Oncol, ISSN 1019-6439, Vol. 32, nr 5, s. 1097-1103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We evaluated long-term use of mobile phones and the risk for brain tumours in case-control studies published so far on this issue. We identified ten studies on glioma and meta-analysis yielded OR = 0.9, 95% CI = 0.8-1.1. Latency period of > or =10-years gave OR = 1.2, 95% CI = 0.8-1.9 based on six studies, for ipsilateral use (same side as tumour) OR = 2.0, 95% CI = 1.2-3.4 (four studies), but contralateral use did not increase the risk significantly, OR = 1.1, 95% CI = 0.6-2.0. Meta-analysis of nine studies on acoustic neuroma gave OR = 0.9, 95% CI = 0.7-1.1 increasing to OR = 1.3, 95% CI = 0.6-2.8 using > or =10-years latency period (four studies). Ipsilateral use gave OR = 2.4, 95% CI = 1.1-5.3 and contra-lateral OR = 1.2, 95% CI = 0.7-2.2 in the > or =10-years latency period group (three studies). Seven studies gave results for meningioma yielding overall OR = 0.8, 95% CI = 0.7-0.99. Using > or =10-years latency period OR = 1.3, 95% CI = 0.9-1.8 was calculated (four studies) increasing to OR = 1.7, 95% CI = 0.99-3.1 for ipsilateral use and OR = 1.0, 95% CI = 0.3-3.1 for contralateral use (two studies). We conclude that this meta-analysis gave a consistent pattern of an association between mobile phone use and ipsilateral glioma and acoustic neuroma using > or =10-years latency period.

  • 323.
    Hardell, Lennart
    et al.
    Department of Oncology, University Hospital, Örebro, Sweden.
    Carlberg, Michael
    Department of Oncology, University Hospital, Örebro, Sweden.
    Söderqvist, Fredrik
    Department of Oncology, University Hospital, Örebro, Sweden.
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Pooled analysis of case-control studies on acoustic neuroma diagnosed 1997-2003 and 2007-2009 and use of mobile and cordless phones2013Inngår i: International Journal of Oncology, ISSN 1019-6439, E-ISSN 1791-2423, Vol. 43, nr 4, s. 1036-1044Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We previously conducted a case-control study of acoustic neuroma. Subjects of both genders aged 20-80 years, diagnosed during 1997-2003 in parts of Sweden, were included, and the results were published. We have since made a further study for the time period 2007-2009 including both men and women aged 18-75 years selected from throughout the country. These new results for acoustic neuroma have not been published to date. Similar methods were used for both study periods. In each, one population-based control, matched on gender and age (within five years), was identified from the Swedish Population Registry. Exposures were assessed by a self-administered questionnaire supplemented by a phone interview. Since the number of acoustic neuroma cases in the new study was low we now present pooled results from both study periods based on 316 participating cases and 3,530 controls. Unconditional logistic regression analysis was performed, adjusting for age, gender, year of diagnosis and socio-economic index (SEI). Use of mobile phones of the analogue type gave odds ratio (OR) = 2.9, 95% confidence interval (CI) = 2.0-4.3, increasing with >20 years latency (time since first exposure) to OR = 7.7, 95% CI = 2.8-21. Digital 20 mobile phone use gave OR = 1.5, 95% CI = 1.1-2.1, increasing with latency >15 years to an OR = 1.8, 95% CI = 0.8-4.2. The results for cordless phone use were OR = 1.5, 95% CI = 1.1-2.1, and, for latency of >20 years, OR = 6.5, 95% CI = 1.7-26. Digital type wireless phones (20 and 3G mobile phones and cordless phones) gave OR = 1.5, 95% CI = 1.1-2.0 increasing to OR = 8.1,95% CI = 2.0-32 with latency >20 years. For total wireless phone use, the highest risk was calculated for the longest latency time >20 years: OR = 4.4, 95% CI = 2.2-9.0. Several of the calculations in the long latency category were based on low numbers of exposed cases. Ipsilateral use resulted in a higher risk than contralateral for both mobile and cordless phones. OR increased per 100 h cumulative use and per year of latency for mobile phones and cordless phones, though the increase was not statistically significant for cordless phones. The percentage tumour volume increased per year of latency and per 100 h of cumulative use, statistically significant for analogue phones. This study confirmed previous results demonstrating an association between mobile and cordless phone use and acoustic neuroma.

  • 324. Hardell, Lennart
    et al.
    Carlberg, Michael
    Söderqvist, Fredrik
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Re: time trends in brain tumor incidence rates in Denmark, Finland, Norway, and Sweden, 1974-20032010Inngår i: Journal of the National Cancer Institute, ISSN 0027-8874, E-ISSN 1460-2105, Vol. 102, nr 10, s. 740-742Artikkel i tidsskrift (Fagfellevurdert)
  • 325. Hardell, Lennart
    et al.
    Carlberg, Michael
    Söderqvist, Fredrik
    Hansson Mild, Kjell
    Umeå universitet, Medicinsk fakultet, Strålningsvetenskaper, Radiofysik.
    Morgan, L Lloyd
    Long-term use of cellular phones and brain tumours: increased risk associated with use for > 10 years.2007Inngår i: Occup Environ Med, Vol. 64, s. 626-632Artikkel i tidsskrift (Fagfellevurdert)
  • 326.
    Hardell, Lennart
    et al.
    Department of Oncology, University Hospital, SE-701 85 Örebro.
    Söderqvist, Fredrik
    Department of Oncology, University Hospital, SE-701 85 Örebro.
    Carlberg, Michael
    Department of Oncology, University Hospital, SE-701 85 Örebro.
    Zetterberg, Henrik
    Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska University Hospital/Mölndal, SE-431 80 Mölndal.
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Exposure to wireless phone emissions and serum beta-trace protein2010Inngår i: International Journal of Molecular Medicine, ISSN 1107-3756, E-ISSN 1791-244X, Vol. 26, nr 2, s. 301-306Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The lipocalin type of prostaglandin D synthase or β-trace protein is synthesized in the choroid plexus, leptomeninges and oligodendrocytes of the central nervous system and is secreted into the cerebrospinal fluid. β-trace protein is the key enzyme in the synthesis of prostaglandin D2, an endogenous sleep-promoting neurohormone in the brain. Electromagnetic fields (EMF) in the radiofrequency (RF) range have in some studies been associated with disturbed sleep. We studied the concentration of β-trace protein in blood in relation to emissions from wireless phones. This study included 62 persons aged 18-30 years. The concentration of β-trace protein decreased with increasing number of years of use of a wireless phone yielding a negative β coefficient = -0.32, 95% confidence interval -0.60 to -0.04. Also cumulative use in hours gave a negative β coefficient, although not statistically significant. Of the 62 persons, 40 participated in an experimental study with 30 min exposure to an 890-MHz GSM signal. No statistically significant change of β-trace protein was found. In a similar study of the remaining 22 participants with no exposure, β-trace protein increased significantly over time, probably due to a relaxed situation. EMF emissions may down-regulate the synthesis of β-trace protein. This mechanism might be involved in sleep disturbances reported in persons exposed to RF fields. The results must be interpreted with caution since use of mobile and cordless phones were self-reported. Awareness of exposure condition in the experimental study may have influence β-trace protein concentrations.

  • 327.
    Hedelin, Rikard
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Bjerle, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Henriksson-Larsén, K
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Cardiac autonomic imbalance in an overtrained athlete.2000Inngår i: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 32, nr 9, s. 1531-1533Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: In order to investigate overtraining-related adaptations in the autonomic nervous system, cardiac autonomic activity was examined in a junior cross-country skier who presented with reduced performance in competitions, early breathlessness during training sessions, and accumulated central fatigue. METHODS: Power spectral analysis of heart rate variability (HRV) was performed before, when overtrained (OT), and after recovery (Rec). RESULTS: In the overtrained state, high frequency (HF) and total powers in the lying position were higher compared with before and after. In normalized units, the increased HF in OT was even more prominent and clearly higher than in any control subject, and it was reversed in Rec. Resting heart rate was slightly reduced in OT and returned to baseline in Rec. CONCLUSIONS: The shift toward increased heart rate variability, particularly in the HF range, together with a reduced resting heart rate suggest a cardiac autonomic imbalance with extensive parasympathetic modulation in this athlete when overtrained.

  • 328.
    Hedman, Angelica
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-90182 Umeå, Sweden.
    Gogani, J. Bahar
    Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-90182 Umeå, Sweden.
    Granström, M.
    Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-90182 Umeå, Sweden.
    Johansson, Lennart
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Andersson, Jonas S.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Ramebäck, H.
    Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-90182 Umeå, Sweden; Chalmers University of Technology, Department of Chemical and Biological Engineering, Nuclear Chemistry, SE-41296 Göteborg, Sweden.
    Characterization of HPGe detectors using Computed Tomography2015Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 785, nr 11 June 2015, s. 21-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Computed Tomography (CT) high resolution imaging have been used to investigate if there is a significant change in the crystal-to-window distance, i.e. the air gap thickness, in a small n-type detector cooled to 77 K, and in a medium sized p-type HPGe detector when cooled to 100 K. The findings were compared to detector dimension data made available by the manufacturer. The air gap thickness increased by (0.38 +/- 0.07) mm for the n-type detector and by (0.40 +/- 0.15) mm for the p-type detector when the detectors were cooled to 77 resp. 100 K compared to at room temperature. Monte Carlo calculations indicate that these differences have a significant impact on the efficiency in close geometries (< 5 cm). In the energy range of 40-700 keV with a source placed directly on endcap, the change in detector efficiency with temperature is 1.9-2.9% for the n-type detector and 0.3-2.1% for the p-type detector. The measured air gap thickness when cooling the detector was 1.1 mm thicker than manufacturer data for the n-type detector and 0.2 mm thicker for the p-type detector. In the energy range of 40-700 keV and with a source on endcap, this result in a change in detector efficiency of 5.2-7.1% for the n-type detector and 0.2-1.0% for the p-type detector, Le the detector efficiency is overestimated using data available by the manufacturer. (C) 2015 Elsevier B.V. All rights reserved.

  • 329. Heggelund, Julie E.
    et al.
    Haugen, Espen
    Lygren, Birgitte
    Mackenzie, Alasdair
    Holmner, Åsa
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Vasile, Francesca
    Reina, Jose J.
    Bernardi, Anna
    Krengel, Ute
    Both El Tor and classical cholera toxin bind blood group determinants2012Inngår i: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 418, nr 4, s. 731-735Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cholera is a disease which shows a clear blood group profile, with blood group 0 individuals experiencing the most severe symptoms. For a long time, the cholera toxin has been suspected to be the main culprit of this blood group dependence. Here, we show that both El Tor and classical cholera toxin B-pentamers do indeed bind blood group determinants (with equal affinities), using Surface Plasmon Resonance and NMR spectroscopy. Together with previous structural data, this confirms our earlier hypothesis as to the molecular basis of cholera blood group dependence, with an interesting twist: the shorter blood group H-determinant characteristic of blood group 0 individuals binds with similar binding affinity compared to the A-determinant, however, with different kinetics. (C) 2012 Elsevier Inc. All rights reserved.

  • 330.
    Heldestad, Victoria
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Hörnsten, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Obayashi, Konen
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Suhr, Ole B
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Nordh, Erik
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Comparison of quantitative sensory testing and heart rate variability in Swedish Val30Met ATTR2011Inngår i: Amyloid: Journal of Protein Folding Disorders, ISSN 1350-6129, E-ISSN 1744-2818, Vol. 18, nr 4, s. 183-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Patients with transthyretin amyloidosis (ATTR) polyneuropathy, a hereditary fatal disease, often report defects in both thermal perception and autonomic nervous system function as their first clinical symptoms. While elevated thermal perception thresholds (TPT) for cold and warmth only recently have been shown as an early marker of small nerve fiber dysfunction in these patients, heart rate variability (HRV) has frequently been used to quantify autonomic neuropathy. The main purpose with this report was to elucidate a possible relationship between estimates of HRV and TPT in a selected group of early and late-onset Swedish Val30Met ATTR patients. The results show significantly more pronounced elevation of TPT in early compared to late-onset patients. Significant correlations between HRV and TPT were found among late-onset cases, indicating a possible relationship between loss of thin nerve fibers in somatic and autonomic nerves, while generally no such relationships were found among early-onset cases. This observation emphasizes the importance of testing both HRV and TPT to ensure optimal early detection of neuropathic changes in an as wide as possible range of small nerve fibers in suspected ATTR patients. This is of particular importance as the phenotype of the ATTR disease varies between groups with different age of onset.

  • 331. Hellström, Max
    et al.
    Granberg, Christoffer
    Lundman, Josef
    Riklund, Katrine
    Andersson, Jonas
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Introducing PySkinDose, a novel framework for patient peak skin dose estimation in interventional radiology2020Konferansepaper (Fagfellevurdert)
  • 332.
    Henein, Mark
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Tossavainen, Erik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Söderberg, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Grönlund, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Gonzalez, Manuel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Lindqvist, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Left atrial strain rate estimates PCWP2013Inngår i: International cardiovascular forum, ISSN 2409-3424, nr 1, s. 25-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: Raised left atrial (LA) pressure is a common pathway for many pathologies and is known for its complications. It has a direct effect on LA cavity size and potentially also its function. We hypothesized that raised LA pressure, as shown by pulmonary capillary wedge pressure (PCWP), correlates with severity of global LA deformation abnormalities during atrial systole (LASRa). DESIGN AND PATIENTS: We prospectively studied 46 consecutive patients, mean age 61 ±13 years, 17 males, of various etiologies who underwent right heart catheterization and simultaneous Doppler echocardiography using spectral, tissue Doppler and speckle tracking echocardiography techniques for assessing LA structure and function. RESULTS: PCWP correlated with direct measurements of LA structure and function: LA volume (r= 0.43, p<0.01) and LASRa (r=0.79, p<0.001). PCWP correlated also with other indirect measures of LA pressure such as E/A (r=0.65, p<0.001), E wave deceleration time (r=0.54, p<0.001), E/e’ (r=0.49, p<0.001) and LA systolic filling fraction (r=0.52, p<0.001). However, LASRa together with LA systolic filling fraction, had the highest areas under the curve (0.83 and 0.87, respectively) for identifying patients with PCWP > 15 mmHg. CONCLUSION: PCWP correlates with LA deformation rate during atrial systole and to a higher extent than conventional Doppler measures of raised LA pressures. These findings should have significant clinical implications in correctly identifying breathless patients due to raised LA pressure.

  • 333.
    Henein, Michael
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Schmermund, Axel
    Guerci, Alan
    Erbel, Raimund
    Raggi, Paolo
    High dose and long-term statin therapy accelerate coronary artery calcification2015Inngår i: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 184, s. 581-586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: In randomized clinical trials statins and placebo treated patients showed the same degree of coronary artery calcium (CAC) progression. We reanalyzed data from two clinical trials to further investigate the time and dose dependent effects of statins on CAC. Additionally, we investigated whether CAC progression was associated with incident cardiovascular events.

    METHODS AND RESULTS: Data were pooled from two clinical trials: St. Francis Heart Study (SFHS) (419 and 432 patients treated with placebo and 20mg atorvastatin daily, respectively) and EBEAT Study (164 and 179 patients respectively treated with 10mg and 80mg atorvastatin daily). CAC scores were assessed at baseline, 2years and 4-6years in SFHS; in EBEAT they were measured at baseline and 12months. After a short-term follow-up (12 to 24months) placebo and low dose atorvastatin showed a similar CAC increase, although 80mg/daily atorvastatin increased CAC an additional 12-14% over placebo (p<0.001). In the long-term, atorvastatin caused a greater progression of CAC compared to placebo (additional 1.1%, p=0.04). In SFHS 42 cardiovascular events occurred after the second CT scan. The baseline and progression of CAC were greater in patients with events. However, only baseline CAC and family history of premature cardiovascular disease but not CAC progression were independent predictors of events.

    CONCLUSIONS: Despite a greater CAC increase with high dose and long-term statin therapy, events did not occur more frequently in statin treated patients. This suggests that CAC growth under treatment with statins represents plaque repair rather than continuing plaque expansion.

  • 334.
    Henein, Michael
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Nicoll, Rachel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Schmermund, A.
    Diederichsen, A. C. P.
    Mickley, H.
    Zamorano, P.
    Gueret, P.
    Budoff, M. J.
    European Calcific Coronary Artery Disease (Euro-CCAD) study: the additional value of coronary calcification, to angiography, in investigating angina patients2013Inngår i: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 34, nr Supplement: 1, s. 177-177Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Background and aim: This study is a part of the Euro-CCAD (CalcificCoronary Artery Disease) project, investigating the geographic prevalence of a coronary artery calcium (CAC) score of >400 in patients with no flow-limiting lesions (FLL) as a potential cause for stable angina. With the development of computerized tomographic coronaryangiography (CTCA), assessment of CAC has become less fashionable, although CTCA often fails to determine the exact cause of symptoms in the absence of FLLs.

    Methods: Data from consecutive symptomatic intermediate risk patients (as defined by guidelines), who had both CA and calcium scoring, were compared between USA and Europe as well as between Europeancountries (Denmark, Germany, France and Spain). No patient had a priorcoronary event, intervention, valve disease or kidney failure.

    Results: The inclusion criteria were fulfilled in 4,444 patients, (60% males), mean age 59.3 years (SD 11.3 years). The prevalence of FLL was higher in the USA at 53% (983/1851) than in Europe at 34% (870/2593) as a whole, (p<0.001). The FLL prevalence was also different (p<0.001) within Europe: Denmark 16%, Germany 35%, France 46% and Spain 89%. In patients with no FLL, 9% had CAC >400, with no difference in prevalence between the USA and Europe, irrespective of age and gender. However, within Europe the prevalence of patients without FLL and with a CAC score >400 differed: Spain 22%, Germany 13%, France 10% and Denmark 7%. Within the total patient population 22% of those with CAC score >400 had no FLL.

    Conclusion: Despite the known variability in the current management of symptomatic angina patients at intermediate risk between the USA andEuropean countries, a consistent proportion (nearly 10%) exhibits severe CAC in the absence of flow limiting lesions. The presence of severe CAC could explain their symptoms through compromised coronary flow reserve. These results highlight the potential value of obtaining additional anatomical information by using CAC assessment in symptomatic patients.

  • 335.
    Henein, Michael Y.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Umeå Heart Centre.
    Koulaouzidis, George
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. Umeå Heart Centre.
    Granåsen, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Guerci, Alan
    Department of Research, St Francis Hospital, Roslyn, NY, USA.
    Schmermund, Axel
    Bethanien Hospital, Frankfurt, Germany.
    The natural history of coronary calcification: a meta-analysis from St Francis and EBEAT trials2013Inngår i: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 168, nr 4, s. 3944-3948Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND AND AIM: Coronary artery calcium score (CACs) is an established quantitative tool for assessing subclinical atherosclerosis. The aim of this study was to assess in a meta-analysis model the natural history and reproducibility of CACs measurements obtained from St Francis and EBEAT trials.

    METHODS: We analysed data from 649 individuals: 443 on placebo with 2year follow-up from St Francis trial (Study A) and 209 on 10mg atorvastatin with 1year follow-up of EBEAT trial (Study B). Total CACs and that in the left coronary artery (LCA) branches, left main stem (LMS), left anterior descending (LAD), left circumflex (Cx) and right coronary artery (RCA) were analysed. In view of the wide CACs spectrum, data were logarithmically transformed before the analyses and mixed model analysis was used to evaluate the change of CACs over time.

    RESULTS: The overall agreement between the two measurements was fairly good, showing a small but significant increase in CAC: 68% of the group as a whole presented an increase in CACs, 23% of the cohort had negligible change in CACs of <10% irrespective of the baseline CACs; and the remaining 10% showed a fall in CACs. Both studies showed similar patterns. The analysis of individual coronary arteries showed significantly higher variability of measurements in the RCA than in the LCA. Males had higher baseline CACs than females, but the rate of progression was not different between genders, irrespectively of age and baseline score.

    CONCLUSION: The natural history of CACs was overtime progression in the majority of subjects, irrespective of gender. The higher variability in RCA measurements could be related to the low baseline CACs or exaggerated movement of the right side atrioventricular ring, whereas those for LCA branches are influenced by the branch allocation of the CACs. Large changes to and from zero, might be related to technical limitations.

  • 336.
    Henein, Michael Y.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Nicoll, Rachel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Schmermund, A.
    Diederichsen, A. C. P.
    Mickley, H.
    Zamorano, P.
    Gueret, P.
    Budoff, M. J.
    European Calcific Coronary Artery Disease (Euro-CCAD) study: the relationship between coronary calcification and flow limiting lesion in symptomatic patients2013Inngår i: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 34, nr Supplement: 1, s. 723-723Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Background and aim: This study is a part of the Euro-CCAD (CalcificCoronary Artery Disease) project, investigating the geographic prevalence of a coronary artery calcium (CAC) score of >400 in patients with no flow-limiting lesions (FLL) as a potential cause for stable angina. With the development of computerized tomographic coronaryangiography (CTCA), assessment of CAC has become less fashionable, although CTCA often fails to determine the exact cause of symptoms in the absence of FLLs.

    Methods: Data from consecutive symptomatic intermediate risk patients (as defined by guidelines), who had both CA and calcium scoring, were compared between USA and Europe as well as between Europeancountries (Denmark, Germany, France and Spain). No patient had a priorcoronary event, intervention, valve disease or kidney failure.

    Results: The inclusion criteria were fulfilled in 4,444 patients, (60% males), mean age 59.3 years (SD 11.3 years). The prevalence of FLL was higher in the USA at 53% (983/1851) than in Europe at 34% (870/2593) as a whole, (p<0.001). The FLL prevalence was also different (p<0.001) within Europe: Denmark 16%, Germany 35%, France 46% and Spain 89%. In patients with no FLL, 9% had CAC >400, with no difference in prevalence between the USA and Europe, irrespective of age and gender. However, within Europe the prevalence of patients without FLL and with a CAC score >400 differed: Spain 22%, Germany 13%, France 10% and Denmark 7%. Within the total patient population 22% of those with CAC score >400 had no FLL.

    Conclusion: Despite the known variability in the current management of symptomatic angina patients at intermediate risk between the USA andEuropean countries, a consistent proportion (nearly 10%) exhibits severe CAC in the absence of flow limiting lesions. The presence of severe CAC could explain their symptoms through compromised coronary flow reserve. These results highlight the potential value of obtaining additional anatomical information by using CAC assessment in symptomatic patients.

  • 337.
    Hildeman, Anders
    et al.
    Department of Mathematical Sciences, Chalmers University of Technology, Sweden.
    Bolin, David
    Department of Mathematical Sciences, Chalmers University of Technology, Sweden.
    Wallin, Jonas
    Department of Statistics, Lund University.
    Johansson, Adam
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Nyholm, Tufve
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Asklund, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Onkologi.
    Yu, Jun
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Hildeman, A., Bolin, D., Wallin, J., Johansson, A., Nyholm, T., Asklund, T., and Yu, J. Whole-brain substitute CT generation using Markov random field mixture models.2016Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Computed tomography (CT) equivalent information is needed for attenuation correction in PET imaging and for dose planning in radiotherapy. Prior work has shown that Gaussian mixture models can be used to generate a substitute CT (s-CT) image from a specific set of MRI modalities. This work introduces a more flexible class of mixture models for s-CT generation, that incorporates spatial dependency in the data through a Markov random field prior on the latent field of class memberships associated with a mixture model. Furthermore, the mixture distributions are extended from Gaussian to normal inverse Gaussian (NIG), allowing heavier tails and skewness. The amount of data needed to train a model for s-CT generation is of the order of 10^8 voxels. The computational efficiency of the parameter estimationand prediction methods are hence paramount, especially when spatial dependency is included in the models. A stochastic Expectation Maximization (EM) gradient algorithm is proposed in order to tackle this challenge. The advantages of the spatial model and NIG distributions are evaluated with a cross-validation study based ondata from 14 patients. The study show that the proposed model enhances the predictive quality of the s-CT images by reducing the mean absolute error with 17.9%. Also, the distribution of CT values conditioned on the MR images are better explainedby the proposed model as evaluated using continuous ranked probability scores.

  • 338. Hocking, Bruce
    et al.
    Hansson Mild, Kjell
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Guidance note: Risk management of workers with medical electronic devices and metallic implants in electromagnetic fields.2008Inngår i: International Journal of Occupational Safety and Ergonomics, ISSN 1080-3548, E-ISSN 2376-9130, Vol. 14, nr 2, s. 217-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Medical electronic devices and metallic implants are found in an increasing number of workers. Industrialapplications requiring intense electromagnetic fields (EMF) are growing and the potential risk of injuriousinteractions arising from EMF affecting devices or implants needs to be managed. Potential interactionsinclude electromagnetic interference, displacement, and electrostimulation or heating of adjacent tissue,depending on the device or implant and the frequency of the fields. A guidance note, which uses a riskmanagement framework, has been developed to give generic advice in (a) risk identification—implementingprocedures to identify workers with implants and to characterise EMF exposure within a workplace; (b) riskassessment—integrating the characteristics of devices, the anatomical localisation of implants, occupationalhygiene data, and application of basic physics principles; and (c) risk control—advising the worker andemployer regarding safety and any necessary changes to work practices, while observing privacy.

  • 339.
    Holmberg, Daniel
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Optimisation of image acquisition and reconstruction of 111In-pentetrotide SPECT2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this study is to optimise the acquisition and reconstruction for SPECT with 111In- pentetrotide with the iterative reconstruction software OSEMS. For 111In-pentetrotide SPECT, the uptake in the tumour is usually high compared to uptake in normal tissue. It may, however, be difficult to detect small tumours with the SPECT method because of high noise levels and the low spatial resolution. The liver is a common region for somatostatin-positive metastases, and to visually detect small tumours in the liver, as early as possible, is important for an effective treatment of the cancer disease.

    The study concentrates on the acquired number of projections, the subset size in the OSEM reconstruction and evaluates contrast as a function of noise for a range of OSEM iterations. The raw-data projections are produced using Monte Carlo simulations of an anthropomorphic phantom, including tumours in the liver. Two General Electric (GE) collimators are evaluated, the extended low-energy general-purpose (ELEGP) and the medium energy general-purpose (MEGP) collimator. Three main areas of reconstruction are investigated. First the reconstructions are performed for so called full time scans with the acquisition time used clinically. Also the effect of performing the examination in half-time or with half the injected activity is evaluated with the most optimal settings gained from the full time scans for both collimators. In addition images reconstructed without model-based compensation are also included for comparison.

    This study is a continuation of a previous study on 111In-pentetrotide SPECT where collimator choice and model-based compensation were evaluated for a cylindrical phantom representing small tumours in liver background. As in the previous study, ELEGP proved to be the better collimator. For ELEGP, the most optimal setting was 30 projection angles and a subset size of 6 projections in the OSEM reconstruction, and for MEGP optimal setting was 60 projections and 4 subsets. The difference between the different collimator settings were, however, rather small but proven significant. For both collimators the half-time scan including model-based compensation was better compared to the full-time reconstructions without model-based compensation.

    Fulltekst (pdf)
    Master's Thesis Daniel Holmberg
  • 340.
    Holmberg, Daniel
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Sundström, Torbjörn
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Riklund, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Axelsson, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Ljungberg, Michael
    Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Reducing scanning time to 50% for In-111 pentetreotide SPECT when using model-based compensation2012Inngår i: 2012 IEEE nuclear science symposium and medical imaging conference record (NSS/MIC) / [ed] Bo Yu, IEEE, 2012, s. 2946-2949Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In In-111-pentetreotide SPECT, it can be difficult to detect small tumors because of high noise levels and low spatial resolution. The aim of this study was to perform optimization of tumor detection in the liver, with regards to the acquisition and reconstruction protocol for In-111-pentetreotide SPECT with model-based compensation included in the OSEM reconstruction. We were also interested in the effect of performing the examination in half of the time or with half the administered activity. Image reconstruction without model-based compensation was also included for comparison. The study concentrates on the acquired number of projections and the subset size in the OSEM reconstruction, and evaluates contrast as a function of noise for a range of OSEM iterations. The raw-data projections are produced using Monte Carlo simulations of a patient-like anthropomorphic phantom with realistic In-111 pentetreotide uptake, including spherical tumors in the liver. Two collimators are evaluated, the extended low-energy general-purpose (ELEGP) and the medium-energy general-purpose (MEGP) collimator. ELEGP proved to be a better collimator when using model-based compensation. The results also indicate that a relatively low number of subsets is advantageous, and that 60 projection angles or even lower is a better choice than 120. For both collimators the time-reduced scan including model-based compensation was better compared to the full-time reconstructions without model-based compensation.

  • 341.
    Holmgren, Madelene
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Holmlund, Petter
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Stoverud, Karen-Helene
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Department of Health Research, SINTEF Digital, NO, Trondheim, Norway.
    Zarrinkoob, Laleh
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Anestesiologi och intensivvård.
    Wåhlin, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Prediction of cerebral perfusion pressure during carotid surgery: A computational fluid dynamics approach2022Inngår i: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 100, artikkel-id 105827Artikkel i tidsskrift (Fagfellevurdert)
    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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  • 342.
    Holmgren, Madelene
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Stoverud, Karen-Helene
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Zarrinkoob, Laleh
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Anestesiologi och intensivvård.
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Middle cerebral artery pressure laterality in patients with symptomatic ICA stenosis2021Inngår i: PLOS ONE, E-ISSN 1932-6203, Vol. 16, nr 1, artikkel-id e0245337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An internal carotid artery (ICA) stenosis can potentially decrease the perfusion pressure to the brain. In this study, computational fluid dynamics (CFD) was used to study if there was a hemispheric pressure laterality between the contra- and ipsilateral middle cerebral artery (MCA) in patients with a symptomatic ICA stenosis. We further investigated if this MCA pressure laterality (ΔPMCA) was related to the hemispheric flow laterality (ΔQ) in the anterior circulation, i.e., ICA, proximal MCA and the proximal anterior cerebral artery (ACA). Twenty-eight patients (73±6 years, range 59–80 years, 21 men) with symptomatic ICA stenosis were included. Flow rates were measured using 4D flow MRI data (PC-VIPR) and vessel geometries were obtained from computed tomography angiography. The ΔPMCA was calculated from CFD, where patient-specific flow rates were applied at all input- and output boundaries. The ΔPMCA between the contra- and ipsilateral side was 6.4±8.3 mmHg (p<0.001) (median 3.9 mmHg, range -1.3 to 31.9 mmHg). There was a linear correlation between the ΔPMCA and ΔQICA (r = 0.85, p<0.001) and ΔQACA (r = 0.71, p<0.001), respectively. The correlation to ΔQMCA was weaker (r = 0.47, p = 0.011). In conclusion, the MCA pressure laterality obtained with CFD, is a promising physiological biomarker that can grade the hemodynamic disturbance in patients with a symptomatic ICA stenosis.

    Fulltekst (pdf)
    fulltext
  • 343.
    Holmgren, Madelene
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Dunås, Tora
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Enheten för demografi och åldrandeforskning (CEDAR).
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Assessment of Cerebral Blood Flow Pulsatility and Cerebral Arterial Compliance With 4D Flow MRI2020Inngår i: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 51, nr 5, s. 1516-1525Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Four-dimensional flow magnetic resonance imaging (4D flow MRI) enables efficient investigation of cerebral blood flow pulsatility in the cerebral arteries. This is important for exploring hemodynamic mechanisms behind vascular diseases associated with arterial pulsations.

    PURPOSE: To investigate the feasibility of pulsatility assessments with 4D flow MRI, its agreement with reference two-dimensional phase-contrast MRI (2D PC-MRI) measurements, and to demonstrate how 4D flow MRI can be used to assess cerebral arterial compliance and cerebrovascular resistance in major cerebral arteries.

    STUDY TYPE: Prospective.

    SUBJECTS: Thirty-five subjects (20 women, 79 ± 5 years, range 70-91 years).

    FIELD STRENGTH/SEQUENCE: 4D flow MRI (PC-VIPR) and 2D PC-MRI acquired with a 3T scanner.

    ASSESSMENT: Time-resolved flow was assessed in nine cerebral arteries. From the pulsatile flow waveform in each artery, amplitude (ΔQ), volume load (ΔV), and pulsatility index (PI) were calculated. To reduce high-frequency noise in the 4D flow MRI data, the flow waveforms were low-pass filtered. From the total cerebral blood flow, total PI (PItot ), total volume load (ΔVtot ), cerebral arterial compliance (C), and cerebrovascular resistance (R) were calculated.

    STATISTICAL TESTS: Two-tailed paired t-test, intraclass correlation (ICC).

    RESULTS: There was no difference in ΔQ between 4D flow MRI and the reference (0.00 ± 0.022 ml/s, mean ± SEM, P = 0.97, ICC = 0.95, n = 310) with a cutoff frequency of 1.9 Hz and 15 cut plane long arterial segments. For ΔV, the difference was -0.006 ± 0.003 ml (mean ± SEM, P = 0.07, ICC = 0.93, n = 310) without filtering. Total R was 11.4 ± 2.41 mmHg/(ml/s) (mean ± SD) and C was 0.021 ± 0.009 ml/mmHg (mean ± SD). ΔVtot was 1.21 ± 0.29 ml (mean ± SD) with an ICC of 0.82 compared with the reference. PItot was 1.08 ± 0.21 (mean ± SD).

    DATA CONCLUSION: We successfully assessed 4D flow MRI cerebral arterial pulsatility, cerebral arterial compliance, and cerebrovascular resistance. Averaging of multiple cut planes and low-pass filtering was necessary to assess accurate peak-to-peak features in the flow rate waveforms.

    LEVEL OF EVIDENCE: 2

    Technical Efficacy Stage: 2

    Fulltekst (pdf)
    fulltext
  • 344.
    Holmlund, Petter
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Fluid dynamic principles for analysis of intracranial pressure control: application towards space medicine and hydrocephalus2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Intracranial pressure (ICP) is an important component of the fluid dynamic environment of the brain and plays a central role with regards to the maintenance of normal cerebral blood flow and neuronal function. However, many regulatory mechanisms controlling the ICP are still poorly understood. One major gap in knowledge in this regard is the mechanism behind the postural/gravitational control of ICP. This is partly due to the fact that most ICP investigations are performed with the patients in a supine or recumbent position. Since most people spend 16 hours a day in an upright position, understanding these mechanics is highly motivated. Also spurring research on this topic is the increasing number of reports of the spaceflight-associated neuro-ocular syndrome (SANS) found in astronauts after prolonged exposure to weightlessness (i.e. microgravity), where evidence suggests that a disrupted balance between ICP and intraocular pressure (IOP) may be an underlying cause. Understanding how ICP is regulated with respect to posture could therefore provide important insight into the alterations introduced by microgravity, where postural effects are removed, and how to improve the safety of astronauts who are susceptible to this syndrome. Here on earth, disturbances in the ICP or cerebrospinal fluid (CSF) dynamics are associated with the development of chronic neurological diseases. One particular disease of interest is communicating hydrocephalus, where the cerebral ventricles are enlarged despite the absence of macroscopic CSF flow obstructions. A common finding in these patients is that of altered pulsatile flow in the CSF. The overall aim of this thesis was to utilize fluid dynamic principles to describe and validate potential regulatory mechanisms behind postural changes in ICP and causes of ventriculomegaly. The thesis is based on four scientific papers (paper I—IV).

    A postural dependency of the IOP-ICP pressure difference was verified by simultaneous measurements of ICP (assessed through lumbar puncture) and IOP (measured with an Applanation Resonance Tonometer) (paper I). Based on these measurements, a 24-hour average of the IOP-ICP pressure difference at the level of the eye was estimated for the state of microgravity, predicting a reduced pressure difference in space compared with that on earth.

    A hypothesis where postural changes in ICP are described by hydrostatic effects in the venous system, and where these effects are altered by the collapse of the internal jugular veins (IJVs) in more upright positions, was evaluated (paper II and III). Using ultrasound data, it was shown that the venous hydrostatic pressure gradient was balanced by viscous pressure losses in the collapsed IJVs to uphold a near atmospheric pressure at the level of the neck in the upright posture (paper II). A full evaluation of the hypothesis was then performed, based on simultaneous assessment of ICP, central venous pressure (through a PICC-line) and venous collapse in 7 postures of upper-body tilt in healthy volunteers (paper III).The proposed description could accurately predict the general changes seen in the measured ICP for all investigated postures (mean difference: -0.03±2.7 mmHg or -4.0±360 Pa).

    Pulsatile CSF flow-induced pressure differences between the ventricles and subarachnoid space were evaluated as a source for ventriculomegaly in communicating hydrocephalus (paper IV). The pressure distributions resulting from the pulsatile CSF flow were calculated using computational fluid dynamics based on MRI data. The estimated pressures revealed a net pressure difference (mean: 0.001±0.003 mmHg or 0.2±0.4 Pa, p=0.03) between the ventricles and the subarachnoid space, over the cardiac cycle, with higher pressure in the third and lateral ventricles.

    In conclusion, the results of this thesis support venous hydrostatics and jugular venous collapse as key governing factors in the postural/gravitational control of ICP. Furthermore, a postural dependency of the IOP-ICP pressure difference was demonstrated, providing a potential explanation for how an imbalance between the pressure of the eye and brain can be introduced in microgravity. Computational fluid dynamic analysis revealed that the altered pulsations in communicating hydrocephalus generate a pressure gradient within the CSF system. However, the gradient was small and additional effects are probably needed to explain the ventriculomegaly in these patients. 

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  • 345.
    Holmlund, Petter
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Koskinen, Lars-Owe D.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Sundström, Nina
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Venous collapse regulates intracranial pressure in upright body positions2018Inngår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 314, nr 3, s. R377-R385Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent interest in intracranial pressure (ICP) in the upright posture has revealed that the mechanisms regulating postural changes in ICP are not fully understood. We have suggested an explanatory model where the postural changes in ICP depend on well-established hydrostatic effects in the venous system and where these effects are interrupted by collapse of the internal jugular veins (IJVs) in more upright positions. The aim of this study was to investigate this relationship by simultaneous invasive measurements of ICP, venous pressure and IJV collapse in healthy volunteers. ICP (monitored via the lumbar route), central venous pressure (PICC-line) and IJV cross-sectional area (ultrasound) were measured in 11 healthy volunteers (47±10 years) in seven positions, from supine to sitting (0°-69°). Venous pressure and anatomical distances were used to predict ICP in accordance with the explanatory model, and IJV area was used to assess IJV collapse. The hypothesis was tested by comparing measured ICP to predicted ICP. Our model accurately described the general behavior of the observed postural ICP changes (mean difference: -0.03±2.7 mmHg). No difference was found between predicted and measured ICP for any tilt-angle (p-values: 0.65 - 0.94). The results support the hypothesis that postural ICP changes are governed by hydrostatic effects in the venous system and IJV collapse. This improved understanding of the postural ICP regulation may have important implications for the development of better treatments for neurological and neurosurgical conditions affecting ICP.

  • 346.
    Holmlund, Petter
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Johansson, Elias
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Ambarki, Khalid
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Koskinen, Lars-Owe D.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Jugular vein collapse in upright and its relation to intracranial pressure regulation2017Inngår i: Journal of Cerebral Blood Flow and Metabolism, ISSN 0271-678X, E-ISSN 1559-7016, Vol. 37, s. 297-297Artikkel i tidsskrift (Fagfellevurdert)
  • 347.
    Holmlund, Petter
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Qvarlander, Sara
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Can pulsatile CSF flow across the cerebral aqueduct cause ventriculomegaly?: A prospective study of patients with communicating hydrocephalus.2019Inngår i: Fluids and Barriers of the CNS, E-ISSN 2045-8118, Vol. 16, nr 1, artikkel-id 40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Communicating hydrocephalus is a disease where the cerebral ventricles are enlarged. It is characterized by the absence of detectable cerebrospinal fluid (CSF) outflow obstructions and often with increased CSF pulsatility measured in the cerebral aqueduct (CA). We hypothesize that the cardiac-related pulsatile flow over the CA, with fast systolic outflow and slow diastolic inflow, can generate net pressure effects that could source the ventriculomegaly in these patients. This would require a non-zero cardiac cycle averaged net pressure difference (ΔPnet) over the CA, with higher average pressure in the lateral and third ventricles.

    Methods: We tested the hypothesis by calculating ΔPnet across the CA using computational fluid dynamics based on prospectively collected high-resolution structural (FIESTA-C, resolution 0.39 × 0.39 × 0.3 mm3) and velocimetric (2D-PCMRI, in-plane resolution 0.35 × 0.35 mm2) MRI-data from 30 patients investigated for communicating hydrocephalus.

    Results: The ΔPnet due to CSF pulsations was non-zero for the study group (p = 0.03) with a magnitude of 0.2 ± 0.4 Pa (0.001 ± 0.003 mmHg), with higher pressure in the third ventricle. The maximum pressure difference over the cardiac cycle ΔPmax was 20.3 ± 11.8 Pa and occurred during systole. A generalized linear model verified an association between ΔPnet and CA cross-sectional area (p = 0.01) and flow asymmetry, described by the ratio of maximum inflow/outflow (p = 0.04), but not for aqueductal stroke volume (p = 0.35).

    Conclusions: The results supported the hypothesis with respect to the direction of ΔPnet, although the magnitude was low. Thus, although the pulsations may generate a pressure difference across the CA it is likely too small to explain the ventriculomegaly in communicating hydrocephalus.

    Fulltekst (pdf)
    fulltext
  • 348.
    Holmlund, Petter
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Stoverud, Karen-Helene
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Department of Health Research, SINTEF Digital, Trondheim, Norway.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Mathematical modelling of the CSF system: effects of microstructures and posture on optic nerve subarachnoid space dynamics2022Inngår i: Fluids and Barriers of the CNS, E-ISSN 2045-8118, Vol. 19, nr 1, artikkel-id 67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: The pressure difference between the eye and brain in upright postures may be affected by compartmentalization of the optic nerve subarachnoid space (ONSAS). Both pressure and deformation will depend on the microstructures of the ONSAS, and most likely also on ocular glymphatic clearance. Studying these factors could yield important knowledge regarding the translaminar pressure difference, which is suspected to play a role in normal-tension glaucoma.

    Methods: A compartment model coupling the ONSAS with the craniospinal CSF system was used to investigate the effects of microstructures on the pressure transfer through the ONSAS during a posture change from supine to upright body postures. ONSAS distensibility was based on MRI measurements. We also included ocular glymphatic flow to investigate how local pressure gradients alter this flow with changes in posture.

    Results: A compartmentalization of the ONSAS occurred in the upright posture, with ONSAS porosity (degree of microstructural content) affecting the ONSAS pressure (varying the supine/baseline porosity from 1.0 to 0.75 yielded pressures between − 5.3 and − 2 mmHg). Restricting the minimum computed porosity (occurring in upright postures) to 0.3 prevented compartmentalization, and the ONSAS pressure could equilibrate with subarachnoid space pressure (− 6.5 mmHg) in ≤ 1 h. The ocular glymphatics analysis predicted that substantial intraocular-CSF flows could occur without substantial changes in the ONSAS pressure. The flow entering the ONSAS in supine position (both from the intraocular system and from the cranial subarachnoid space) exited the ONSAS through the optic nerve sheath, while in upright postures the flow through the ONSAS was redirected towards the cranial subarachnoid space.

    Conclusions: Microstructures affect pressure transmission along the ONSAS, potentially contributing to ONSAS compartmentalization in upright postures. Different pathways for ocular glymphatic flow were predicted for different postures.

    Fulltekst (pdf)
    fulltext
  • 349.
    Holmlund, Petter
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Stoverud, Karen-Helene
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wåhlin, Anders
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Malm, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Jóhannesson, Gauti
    Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM). Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Eklund, Anders
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Posture-dependent collapse of the optic nerve subarachnoid space: A combined MRI and modeling study2021Inngår i: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 62, nr 4, artikkel-id 26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: We hypothesize that a collapse of the optic nerve subarachnoid space (ONSAS) in the upright posture may protect the eyes from large translamina cribrosa pressure differences (TLCPD) believed to play a role in various optic nerve diseases (e.g., glaucoma). In this study, we combined magnetic resonance imaging (MRI) and mathematical modeling to investigate this potential ONSAS collapse and its effects on the TLCPD.

    METHODS: First, we performed MRI on six healthy volunteers in 6° head-down tilt (HDT) and 13° head-up tilt (HUT) to assess changes in ONSAS volume (measured from the eye to the optic canal) with changes in posture. The volume change reflects optic nerve sheath (ONS) distensibility. Second, we used the MRI data and mathematical modeling to simulate ONSAS pressure and the potential ONSAS collapse in a 90° upright posture.

    RESULTS: The MRI showed a 33% decrease in ONSAS volume from the HDT to HUT (P < 0.001). In the upright posture, the simulations predicted an ONSAS collapse 25 mm behind lamina cribrosa, disrupting the pressure communication between the ONSAS and the intracranial subarachnoid space. The collapse reduced the simulated postural increase in TLCPD by roughly 1 mm Hg, although this reduction was highly sensitive to ONS distensibility, varying between 0 and 4.8 mm Hg when varying the distensibility by ± 1 SD.

    CONCLUSIONS: The ONSAS volume along the optic nerve is posture dependent. The simulations supported the hypothesized ONSAS collapse in the upright posture and showed that even small changes in ONS stiffness/distensibility may affect the TLCPD.

    Fulltekst (pdf)
    fulltext
  • 350.
    Holmner, Åsa
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Rocklöv, Joacim
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Ng, Nawi
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Nilsson, Maria
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Epidemiologi och global hälsa.
    Climate change and eHealth: a promising strategy for health sector mitigation and adaptation2012Inngår i: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 5, s. 1-9Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Climate change is one of today's most pressing global issues. Policies to guide mitigation and adaptation are needed to avoid the devastating impacts of climate change. The health sector is a significant contributor to greenhouse gas emissions in developed countries, and its climate impact in low-income countries is growing steadily. This paper reviews and discusses the literature regarding health sector mitigation potential, known and hypothetical co-benefits, and the potential of health information technology, such as eHealth, in climate change mitigation and adaptation. The promising role of eHealth as an adaptation strategy to reduce societal vulnerability to climate change, and the link's between mitigation and adaptation, are also discussed. The topic of environmental eHealth has gained little attention to date, despite its potential to contribute to more sustainable and green health care. A growing number of local and global initiatives on 'green information and communication technology (ICT)' are now mentioning eHealth as a promising technology with the potential to reduce emission rates from ICT use. However, the embracing of eHealth is slow because of limitations in technological infrastructure, capacity and political will. Further research on potential emissions reductions and co-benefits with green ICT, in terms of health outcomes and economic effectiveness, would be valuable to guide development and implementation of eHealth in health sector mitigation and adaptation policies.

    Fulltekst (pdf)
    fulltext
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