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  • 101. Horner, K
    et al.
    Islam, M
    Flygare, Lennart
    Tsiklakis, K
    Whaites, E
    Basic principles for use of dental cone beam computed tomography: consensus guidelines of the European Academy of Dental and Maxillofacial Radiology2009In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 38, no 4, p. 187-195Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To develop "basic principles" on the use of dental cone beam CT by consensus of the membership of the European Academy of Dental and Maxillofacial Radiology.

    METHODS: A guideline development panel was formed to develop a set of draft statements using existing European directives and guidelines on radiation protection. These statements were revised after an open debate of attendees at a European Academy of Dental and Maxillofacial Radiology (EADMFR) Congress in June 2008. A modified Delphi procedure was used to present the revised statements to the EADMFR membership, utilising an online survey in October/November 2008.

    RESULTS: Of the 339 EADMFR members, 282 had valid e-mail addresses and could be alerted to the online survey. A response rate of 71.3% of those contacted by e-mail was achieved. Consensus of EADMFR members, indicated by high level of agreement for all statements, was achieved without a need for further rounds of the Delphi process.

    CONCLUSIONS: A set of 20 basic principles on the use of dental cone beam CT has been devised. They will act as core standards for EADMFR and, it is hoped, will be of value in national standard-setting within Europe.

  • 102. Husberg, Britt
    et al.
    Salehi, Karin
    Peters, Trevor
    Gunnarsson, Ulf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Michanek, Margareta
    Nordenskjöld, Agneta
    Strigård, Karin
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Congenital intestinal malrotation in adolescent and adult patients: a 12-year clinical and radiological survey2016In: SpringerPlus, E-ISSN 2193-1801, Vol. 5, article id 245Article in journal (Refereed)
    Abstract [en]

    Congenital intestinal malrotation is mainly detected in childhood and caused by incomplete rotation and fixation of the intestines providing the prerequisites for life-threatening volvulus of the midgut. The objective of this study was to evaluate a large cohort of adult patients with intestinal malrotation. Thirty-nine patients, 15-67 years, were diagnosed and admitted to a university setting with congenital intestinal malrotation 2002-2013. The patients were divided into three age groups for stratified evaluation. Medical charts were scrutinized, and clinical outcome of surgery was reviewed. Twelve patients presented as emergency cases, whereas 27 were admitted as elective cases. Diagnosis was established in 33 patients who underwent radiological investigation and in the remaining 6 during surgery. A Ladd's operation was performed in 31 symptomatic patients; a conservative strategy was chosen in eight cases. Volvulus was more common in the younger age group. Twenty-six surgically treated patients were available for telephone interview, 1-12 years after surgery. All patients, except one, regarded their general condition improved to a high degree (n = 18) or with some reservation (n = 7). Twelve patients suffered remaining abdominal pain of a chronic and diffuse character. Due to recurrence of malrotation six patients were reoperated. Symptomatic malrotation occurs in both children and the adult population. Improved awareness and an accurately performed CT scan can reveal the malformation and enable surgical treatment. A Ladd's procedure relieved most patients from their severe complaints even when a history of several years of suffering existed.

  • 103. Ilegems, E.
    et al.
    van Krieken, P. P.
    Edlund, P. K.
    Dicker, A.
    Alanentalo, T.
    Eriksson, Maria
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Mandic, S.
    Ahlgren, Ulf
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Berggren, P. -O
    Light scattering as an intrinsic indicator for pancreatic islet cell mass and secretion2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 10740Article in journal (Refereed)
    Abstract [en]

    The pancreatic islet of Langerhans is composed of endocrine cells producing and releasing hormones from secretory granules in response to various stimuli for maintenance of blood glucose homeostasis. In order to adapt to a variation in functional demands, these islets are capable of modulating their hormone secretion by increasing the number of endocrine cells as well as the functional response of individual cells. A failure in adaptive mechanisms will lead to inadequate blood glucose regulation and thereby to the development of diabetes. It is therefore necessary to develop tools for the assessment of both pancreatic islet mass and function, with the aim of understanding cellular regulatory mechanisms and factors guiding islet plasticity. Although most of the existing techniques rely on the use of artificial indicators, we present an imaging methodology based on intrinsic optical properties originating from mature insulin secretory granules within endocrine cells that reveals both pancreatic islet mass and function. We demonstrate the advantage of using this imaging strategy by monitoring in vivo scattering signal from pancreatic islets engrafted into the anterior chamber of the mouse eye, and how this versatile and noninvasive methodology permits the characterization of islet morphology and plasticity as well as hormone secretory status.

  • 104.
    Inkinen, Satu
    et al.
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
    Liukkonen, Jukka
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Ylärinne, Janne
    School of Medicine, Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Puhakka, Pia
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
    Lammi, Mikko
    School of Medicine, Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Virén, Tuomas
    Cancer Center, Kuopio University Hospital, Kuopio, Finland.
    Jurvelin, Jukka
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Töyräs, Juha
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
    Collagen and chondrocyte concentrations control ultrasound scattering in agarose scaffolds2014In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 40, no 9, p. 2162-2171Article in journal (Refereed)
    Abstract [en]

    Ultrasound imaging has been proposed for diagnostics of osteoarthritis and cartilage injuries in vivo. However, the specific contribution of chondrocytes and collagen to ultrasound scattering in articular cartilage has not been systematically studied. We investigated the role of these tissue structures by measuring ultrasound scattering in agarose scaffolds with varying collagen and chondrocyte concentrations. Ultrasound catheters with center frequencies of 9 MHz (7.1–11.0 MHz, −6 dB) and 40 MHz (30.1–45.3 MHz, −6 dB) were applied using an intravascular ultrasound device. Ultrasound backscattering quantified in a region of interest starting right below sample surface differed significantly (p < 0.05) with the concentrations of collagen and chondrocytes. An ultrasound frequency of 40 MHz, as compared with 9 MHz, was more sensitive to variations in collagen and chondrocyte concentrations. The present findings may improve diagnostic interpretation of arthroscopic ultrasound imaging and provide information necessary for development of models describing ultrasound propagation within cartilage.

  • 105.
    Jakobson Mo, Susanna
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Nuclear medicine methods in idiopathic Parkinsonism: pre- and postsynaptic dopamine SPECT2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Single photon emission computed tomography (SPECT) with dopamine transporter (DAT) and dopamine D2 receptor (D2R) ligands can visualise the integrity of the nigrostriatal dopamine system. Parkinson’s disease (PD) and the atypical parkinsonian diseases (APD), progressive supranuclear palsy (PSP) and multiple system atrophy (MSA), have similar symptoms and dopamine depletion, but differ in pharmacological response and prognosis. Clinical differentiation between PD and APD is often difficult in the early stages. The aims of the thesis were to evaluate the differential diagnostic and prognostic value of SPECT in early PD, MSA and PSP, to map the pattern of progression with dopamine SPECT, and map the pattern of dopamine SPECT in non-affected elderly volunteers with a prospective approach. Also, we evaluated the methodological aspects of dopamine SPECT with respect to image evaluation tools, reconstruction parameters and gamma cameras.

    Methods: 172 patients, included in an on-going clinical prospective study on idiopathic parkinsonism, participated in the SPECT study. Also, 31 age-matched healthy controls (HC) were followed within this study. SPECT was done with 123I-FP-Cit (DAT SPECT) and 123I-IBZM (D2R SPECT). Regions of interest (ROI) were used as a standard method for semi-quantitative image analysis.

    Results: SPECT uptake ratios from different gamma cameras could be equalised through correction equations derived from images of a brain-like phantom, provided that attenuation correction was applied. The ROI method had high reproducibility. SPECT uptake  in HC, measured with the ROI method and a volume based (VOI) method rendered similar trends, but gender and age differences in SPECT uptake were more marked with the VOI method, and less pronounced in DAT SPECT compared to D2R SPECT with both methods. The DAT SPECT uptake was significantly reduced in very early disease stage of PD and APD compared to HC. DATSPECT uptake was more reduced in PD with postural and gait disturbance (PIGD) compared to tremor-dominant PD. Decline in DAT SPECT uptake during the first year was more pronounced in PD and PSP compared to HC. D2R SPECT uptake overlapped between untreated PD and APD. After initiated treatment, the D2R SPECT uptake was significantly higher in MSA patients compared to PD, PSP and HC. Decline in D2R SPECT uptake during the first year was not significantly different between patients or compared to HC.

    Conclusions: 123I-FP-Cit SPECT is a valuable and sensitive method to detect early stage idiopathic parkinsonism. A different level of uptake between PIGD-PD compared to TD-PD indicates a prognostic potential. It is not possible to differ between PD, MSA and PSP in early stage with 123I-FP-Cit SPECT and no differential diagnostic value was found using 123I-IBZM SPECT in the early, untreated stage of PD, MSA and PSP. A different pattern of uptake of this ligand in MSA compared to PD and PSP during the first years of L-dopa treatment may, however, indicate a diagnostic value during the follow-up period.

  • 106.
    Jakobson Mo, Susanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Jonasson, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Ögren, Mattias J.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Ögren, Margareta
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Varrone, Andrea
    Eriksson, Linda
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Bäckström, David
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    af Bjerkén, Sara
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Linder, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Dopamine transporter imaging with [18F]FE-PE2I PET and [123I]FP-CIT SPECT – a clinical comparison2018In: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 8, article id 100Article in journal (Refereed)
    Abstract [en]

    Background: Dopamine transporter (DAT) imaging may be of diagnostic value in patients with clinically suspected parkinsonian disease. The purpose of this study was to compare the diagnostic performance of DAT imaging with positron emission computed tomography (PET), using the recently developed, highly DAT-selective radiopharmaceutical [18F]FE-PE2I (FE-PE2I), to the commercially available and frequently used method with [123I]FP-CIT (FP-CIT) single-photon emission computed tomography (SPECT) in early-stage idiopathic parkinsonian syndrome (PS).

    Methods: Twenty-two patients with a clinical de novo diagnosis of PS and 28 healthy controls (HC) participating in an on-going clinical trial of FE-PE2I were analyzed in this study. Within the trial protocol, participants are clinically reassessed 2 years after inclusion. A commercially available software was used for automatic calculation of FP-CIT-specific uptake ratio (SUR). MRI-based volumes of interest combined with threshold PET segmentation were used for FE-PE2I binding potential relative to non-displaceable binding (BPND) quantification and specific uptake value ratios (SUVR).

    Results: PET with FE-PE2I revealed significant differences between patients with a clinical de novo diagnosis of PS and healthy controls in striatal DAT availability (p < 0.001), with excellent accuracy of predicting dopaminergic deficit in early-stage PS. The effect sizes were calculated for FE-PE2I BPND (Glass’s Δ = 2.95), FE-PE2I SUVR (Glass’s Δ = 2.57), and FP-CIT SUR (Glass’s Δ = 2.29). The intraclass correlation (ICC) between FE-PE2I BPND FP-CIT SUR was high in the caudate (ICC = 0.923), putamen (ICC = 0.922), and striatum (ICC = 0.946), p < 0.001. Five of the 22 patients displayed preserved striatal DAT availability in the striatum with both methods. At follow-up, a non-PS clinical diagnosis was confirmed in three of these, while one was clinically diagnosed with corticobasal syndrome. In these patients, FE-PE2I binding was also normal in the substantia nigra (SN), while significantly reduced in the remaining patients. FE-PE2I measurement of the mean DAT availability in the putamen was strongly correlated with BPND in the SN (R = 0.816, p < 0.001). Olfaction and mean putamen DAT availability was correlated using both FE-PE2I BPND and FP-CIT SUR (R ≥ 0.616, p < 0.001).

    Conclusion: DAT imaging with FE-PE2I PET yields excellent basic diagnostic differentiation in early-stage PS, at least as good as FP-CIT SPECT.

  • 107.
    Jakobson Mo, Susanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Stenlund, Hans
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Cross-camera comparison of ROI-based semi-quantitative 123I-IBZM SPECT data in healthy volunteers using an anthropomorphic phantom for calibration2013In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 54, no 5, p. 549-556Article in journal (Refereed)
    Abstract [en]

    Background In (123)I-Iolopride (IBZM) SPECT reference values may diverge between camera systems. If multicenter pooling of normal material databases is needed, differences in measured semi-quantitative data due to equipment performance and reconstruction parameters have to be investigated in each instance to determine the comparability.

    Purpose To explore the differences in (123)I-IBZM measured uptake ratios between two different gamma cameras in healthy controls, the intra-rater reproducibility of the image evaluation method and the possibility to equalize uptake ratios by calibration through an anthropomorphic phantom.

    Material and Methods Differences in ROI-based semi-quantitative data from two different gamma camera systems, the three-headed brain dedicated Neurocam and the two-headed multipurpose hybrid system Infinia Hawkeye, were studied using image data from a group of healthy volunteers and an anthropomorphic brain-phantom scanned with both cameras. Several reconstruction methods and corrections were applied. To test the reliability of the ROI method, the intra-observer reproducibility was determined for the ROI method in this study.

    Results The ROI method had a high reliability. Differences in mean measured uptake (123)I-IBZM ratios in healthy controls varied between 2.9% and 6.5% depending on reconstruction and correction for attenuation and scatter. After calibration, the differences decreased. There were no statistically significant differences between corrected ratios from the two camera systems in the study when images were reconstructed with attenuation correction.

    Conclusion The conformity of uptake ratios in attenuation corrected (123)I-IBZM images derived from the two different cameras was improved by using an anthropomorphic phantom for calibration.

  • 108.
    Jakobson Mo, Susanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Linder, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Birgander, Richard
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Edenbandt, Lars
    Göteborgs Universitet, Avdelningen för molekylär och klinisk medicin.
    Stenlund, Hans
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    123I-FP-Cit and 123I-IBZM SPECT uptake in a prospective normal material analysed with two different semi-quantitative image evaluation tools2013In: Nuclear medicine communications, ISSN 0143-3636, E-ISSN 1473-5628, Vol. 34, no 10, p. 978-989Article in journal (Refereed)
    Abstract [en]

    Objective: The need for age-adjusted and/or sex-adjusted reference values in dopamine transporter (DAT) and dopamine D2 receptor (D2R) imaging with single-photon emission computed tomography (SPECT) in a longitudinal study of parkinsonian diseases was investigated. We used two different image evaluation tools with a cross-sectional and longitudinal statistical approach.

    Materials and methods: Baseline DAT and/or D2R SPECT were performed in 51 healthy controls (HC), age-matched to patients in an ongoing prospective study on idiopathic parkinsonism. Twenty-four HC were re-examined after 3 years and 21 HC were examined again after 5 years. SPECT was performed with I-123-FP-Cit and I-123-IBZM on a two-headed hybrid gamma camera. Regions of interest and volumes of interest (VOIs) were used for image evaluation. A cross-sectional and longitudinal statistical analysis was carried out.

    Results: Fewer sex-based differences and less age dependency were seen in DAT SPECT uptake ratios compared with D2R SPECT uptake ratios and when comparing uptake ratios obtained with regions of interest against those with VOIs. In the cross-sectional analysis, a significant age-dependent decline was seen in women in both DAT and D2R uptakes with the VOI method but not in men with either evaluation method. In the longitudinal dataset, both a slight decline and increase over time were seen in DAT uptake; however, a general pattern of decrease was seen in both men and women in D2R uptake.

    Conclusion: The choice of the image evaluation method can influence the pattern of sex-based and age-related differences. The results speak for the use of age-stratified reference values for women, in particular when using a VOI method.

  • 109.
    Jakobson Mo, Susanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Linder, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Blomstedt, Patric
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Granåsen, Gabriel
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Hariz, Marwan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Unit of Functional Neurosurgery, UCL Institute of Neurology, London, UK.
    Long-term dopamine transporter imaging in Parkinson's disease treated with zona incerta stimulation2016In: Nuclear medicine communications, ISSN 0143-3636, E-ISSN 1473-5628, Vol. 37, no 5, p. 499-508Article in journal (Refereed)
    Abstract [en]

    Objective: The caudal zona incerta (cZI) is a promising, clinically beneficial target for deep brain stimulation (DBS) in Parkinson’s disease (PD). To assess whether DBS of the cZI affects the rate of dopamine terminal dysfunction, PD patients with and without DBS were followed prospectively with 123I FP-Cit single photon emission tomography from the first diagnosis and up to 8 years.

    Methods: Six patients underwent DBS of the cZI during the survey period. Twenty-two PD patients only on pharmacotherapy served as controls. 123I FP-Cit and clinical assessment were performed at baseline and after 1, 3 and 5 years in all patients. Ten patients also underwent a 123I FP-Cit after 8 years. Image data were evaluated semiquantitatively. Mixed-model analysis was used to assess the relative change in 123I FP-Cit uptake and comparison between surgically and conservatively treated PD patients.

    Results: The relative decrease in 123I FP-Cit uptake was more pronounced in DBS-treated patients than in controls in the more affected caudate (P=0.037) and putamen (P=0.013). The annual decrease rates were higher in the less affected than the more affected putamen, and were slightly greater in DBS-treated patients (4.8%, 95%confidence interval: 8.5–2.2%) than in controls (4.0%, 95% confidence interval: 5.1–3.1%).

    Conclusion: This long-term prospective study confirms that the underlying dopaminergic dysfunction continues despite clinical improvement in PD patients with DBS of the cZI. A slightly faster rate of decrease in 123I FP-Cit uptake in these patients compared with conservatively treated PD patients may reflect a more aggressive form of PD.

  • 110.
    Jakobson Mo, Susanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Linder, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Holmberg, Henrik
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Pre- and postsynaptic dopamine SPECT in idiopathic parkinsonian diseases: a follow-up study2013In: BioMed Research International, ISSN 2314-6141, Vol. 2013, p. 143532-Article in journal (Refereed)
    Abstract [en]

    We prospectively evaluated the diagnostic contribution of 123I-FP-Cit (DAT) and 123I-IBZM (IBZM) SPECT in 29 patients with Parkinson’s disease (PD) (74.4 ± 4.2 years) and 28 patients with atypical parkinsonian diseases (APD) (74.3 ± 9.2 years). Twelve had multiple system atrophy (MSA) and 16 progressive supranuclear palsy (PSP). Sixteen age-matched healthy controls (HC) were included. DAT and IBZM SPECTs were made at baseline and after 1 year in all PD patients and in 20 (DAT) and 18 (IBZM) of the APD patients, and after 3 years in 22 (DAT) and 17 (IBZM) of the PD patients and in 10 (DAT) and 10 (IBZM) of the APD patients. The relative DAT uptake decrease was faster in PD and PSP than in HC and MSA. In PSP the DAT uptake was lower than in MSA after 1 year but not after 3 years. Baseline IBZM uptake was not significantly different between patients and HC or between PD and APD. One year after initiated dopaminergic treatment the mean IBZM uptake in the MSA patients remained high compared to PSP and after 3 years compared to PD, PSP, and HC.Thus, the pattern of uptake of these ligands over time may be of value in discriminating between these diagnoses.

  • 111.
    Jakobson Mo, Susanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Linder, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Pre- and postsynaptic dopamine SPECT in the early phase of idiopathic parkinsonism: a population-based study2010In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 37, no 11, p. 2154-2164Article in journal (Refereed)
    Abstract [en]

    PURPOSE: The aim of this study was to assess the diagnostic contribution of pre- and postsynaptic dopamine SPECT in drug-naïve patients with early idiopathic parkinsonism and to investigate possible differences between idiopathic Parkinson's disease (PD) and atypical parkinsonian syndromes (APS) and possible differences in motor subtypes of parkinsonism.

    METHODS: A group of 128 newly diagnosed idiopathic parkinsonian patients and 48 healthy controls was studied. Presynaptic baseline SPECT with (123)I-FP-CIT was performed in all patients and in 120 patients also a baseline postsynaptic SPECT with (123)I-IBZM. Clinical diagnoses were reassessed after 12 months.

    RESULTS: Presynaptic uptake in the putamen and caudate was significantly reduced in patients compared to controls. Presynaptic uptake ratios were not different between PD patients and patients with APS, and postsynaptic uptake in APS was not significantly reduced compared to PD or controls. In half of the APS patients both pre- and postsynaptic uptake ratios were reduced on the same side in the striatum. Impaired motor performance was associated with decreased presynaptic uptake in the putamen in PD. The postural instability and gait difficulty (PIGD) subtype of PD had lower presynaptic uptake ratios than patients with tremor-dominated (TD) symptoms.

    CONCLUSION: Not only presynaptic putamen uptake ratios, but also caudate ratios were reduced in a majority of the patients in our study. At baseline scan, i.e. in an early stage of the disease, the accuracy of excluding APS in the whole study population was 85% using a combination of pre- and postsynaptic SPECT. Already at baseline, lower presynaptic SPECT ratios were seen in PD with PIGD at onset compared to those with TD subtype.

  • 112.
    Jakobson Mo, Susanna
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Linder, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Accuracy of Visual Assessment of Dopamine Transporter Imaging in Early Parkinsonism2015In: Movement Disorders Clinical Practice, ISSN 2330-1619, Vol. 2, no 1, p. 17-23Article in journal (Refereed)
    Abstract [en]

    Dopamine transporter (DaT) imaging may be supportive in the initial clinical diagnostic workup in patients with suspected parkinsonian diseases, given that the method has the potential to detect dopaminergic degeneration. We investigated the diagnostic accuracy of visual assessment of the initial DaT single-photon emission CT (DaT-SPECT) with 123I-FP-CIT in a large group of early-stage parkinsonian patients. After inclusion in a long-term multidisciplinary population-based prospective study, a baseline DaT-SPECT was done in 171 incidental, L-dopa-naïve, parkinsonian patients (102 men and 69 women) and 37 healthy controls (19 men and 18 women). The results of the DaT-SPECTs were linked to criteria-based clinical diagnoses, which were set after a mean follow-up of 4.6 (±1.7) years. The outcome of the visual assessment was also compared with that of a semiquantitative evaluation method using regions of interest to measure uptake ratios in the caudate and putamen. We found that visual assessment of DaT-SPECT in clinically diagnosed incidental Parkinson's disease patients had a sensitivity of 94% and a specificity of 92%, rendering a positive likelihood ratio of 11.75 and a negative likelihood ratio of 0.07. The proportion of false positives was 1.4% and false negatives 4.8% at baseline. These figures were comparable to those of the semiquantitative method. This study demonstrates that visual interpretation of presynaptic dopamine imaging with 123I-FP-CIT offers reliable support in the diagnostic procedure of early parkinsonian diseases.

  • 113.
    Jashari, Fisnik
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Ibrahimi, Pranvera
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Johansson, Elias
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Ahlqvist, Jan
    Umeå University, Faculty of Medicine, Department of Odontology.
    Arnerlöv, Conny
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Garoff, Maria
    Umeå University, Faculty of Medicine, Department of Odontology.
    Jäghagen, Eva Levring
    Umeå University, Faculty of Medicine, Department of Odontology.
    Wester, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Henein, Michael Y
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Atherosclerotic Calcification Detection: A Comparative Study of Carotid Ultrasound and Cone Beam CT2015In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 16, no 8, p. 19978-19988Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND AIM: Arterial calcification is often detected on ultrasound examination but its diagnostic accuracy is not well validated. The aim of this study was to determine the accuracy of carotid ultrasound B mode findings in detecting atherosclerotic calcification quantified by cone beam computed tomography (CBCT).

    METHODS: We analyzed 94 carotid arteries, from 88 patients (mean age 70 ± 7 years, 33% females), who underwent pre-endarterectomy ultrasound examination. Plaques with high echogenic nodules and posterior shadowing were considered calcified. After surgery, the excised plaques were examined using CBCT, from which the calcification volume (mm3) was calculated. In cases with multiple calcifications the largest calcification nodule volume was used to represent the plaque. Carotid artery calcification by the two imaging techniques was compared using conventional correlations.

    RESULTS: Carotid ultrasound was highly accurate in detecting the presence of calcification; with a sensitivity of 88.2%. Based on the quartile ranges of calcification volumes measured by CBCT we have divided plaque calcification into four groups: <8; 8-35; 36-70 and >70 mm3. Calcification volumes ≥8 were accurately detectable by ultrasound with a sensitivity of 96%. Of the 21 plaques with <8 mm3 calcification volume; only 13 were detected by ultrasound; resulting in a sensitivity of 62%. There was no difference in the volume of calcification between symptomatic and asymptomatic patients.

    CONCLUSION: Carotid ultrasound is highly accurate in detecting the presence of calcified atherosclerotic lesions of volume ≥8 mm3; but less accurate in detecting smaller volume calcified plaques. Further development of ultrasound techniques should allow better detection of early arterial calcification.

  • 114.
    Johansson, Adam
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Garpebring, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Asklund, Thomas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Improved quality of computed tomography substitute derived from magnetic resonance (MR) data by incorporation of spatial information: potential application for MR-only radiotherapy and attenuation correction in positron emission tomography2013In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 52, no 7, p. 1369-1373Article in journal (Refereed)
    Abstract [en]

    Background: Estimation of computed tomography (CT) equivalent data, i.e. a substitute CT (s-CT), from magnetic resonance (MR) images is a prerequisite both for attenuation correction of positron emission tomography (PET) data acquired with a PET/MR scanner and for dose calculations in an MR-only radiotherapy workflow. It has previously been shown that it is possible to estimate Hounsfield numbers based on MR image intensities, using ultra short echo-time imaging and Gaussian mixture regression (GMR). In the present pilot study we investigate the possibility to also include spatial information in the GMR, with the aim to improve the quality of the s-CT. Material and methods: MR and CT data for nine patients were used in the present study. For each patient, GMR models were created from the other eight patients, including either both UTE image intensities and spatial information on a voxel by voxel level, or only UTE image intensities. The models were used to create s-CT images for each respective patient. Results: The inclusion of spatial information in the GMR model improved the accuracy of the estimated s-CT. The improvement was most pronounced in smaller, complicated anatomical regions as the inner ear and post-nasal cavities. Conclusions: This pilot study shows that inclusion of spatial information in GMR models to convert MR data to CT equivalent images is feasible. The accuracy of the s-CT is improved and the spatial information could make it possible to create a general model for the conversion applicable to the whole body.

  • 115.
    Johansson, David
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Kosovac, Eldina
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Biomedical Laboratory Science.
    Moharer, Jasmine
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Ljuslinder, Ingrid
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Behnam-Motlagh, Parviz
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Expression of verotoxin-1 receptor Gb3 in breast cancer tissue and verotoxin-1 signal transduction to apoptosis: Bacterial toxins, cancer treatment2009In: BMC Cancer, ISSN 1471-2407, E-ISSN 1471-2407, Vol. 26, no 9, p. 67-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The prerequisite for the potential use of the bacterial toxin verotoxin-1 in the treatment of breast cancer was investigated by first determining the expression of its receptor Gb3 (CD77) in clinical breast cancer tissue specimens. We then examined the cytotoxicity and mechanism of apoptosis induction of Escherichia coli verotoxin-1 (VT-1) in two human breast cancer cell lines. METHODS: Immunohistochemistry for Gb3 expression was performed on cryostat section from 25 breast cancer specimens. The human breast cancer cell lines T47D and MCF-7 were screened for Gb3 expression by flow cytometry. Fluorescein diacetate and LDH release was used to determine cell viability after VT-1 exposure. Apoptosis was studied by measuring caspase activity and DNA-fragmentation. Signal transduction studies were performed on T47D cells with immunoblotting. RESULTS: Gb3 expression was detected in the vascular endothelial cells of all tumours specimens, and in tumour cells in 17 of the specimens. We found no associations between tumour cell Gb3-expression and age, tumour size, TNM-classification, histological type, hormone receptor expression, or survival time. T47D cells strongly expressed Gb3 and were sensitive to the cytotoxicity, caspase activation and DNA fragmentation by VT-1, whereas MCF-7 cells with faint Gb3-expression were insensitive to VT-1. VT-1 (0.01 - 5 microg/L) exposure for 72 h resulted in a small percentage of viable T47D cells whereas the cytotoxicity of cells pre-treated with 2 micromol/L D, L-treo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP, an inhibitor of glucosylceramide synthesis) was eliminated (< or = 0.1 microg/L VT-1) or reduced (0.5 - 5 microg/L VT-1). VT-1 did not cause cellular LDH-release or cell cycle arrest. VT-1 induction of caspase-3 (0.1, 1, and 5 microg/L VT-1), -8, and -9 (1 and 5 microg/L VT-1) activity and DNA fragmentation of T47D cells was blocked by PPMP. Key components of MAP kinase signalling pathways that control mitochondrial function were investigated. VT-1 0.1 - 5 microg/L induced phosphorylation of JNK as well as MKK3/6 suggesting that survival signal pathways were overruled by VT-1-induced JNK activation leading to mitochondrial depolarization, caspase-9 activation and apoptosis. CONCLUSION: The high specificity and apoptosis-inducing properties of verotoxin-1 indicates that the toxin potentially may be used for treatment of Gb3-expressing breast cancer.

  • 116.
    Johansson, Elias
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Benhabib, Hadas
    Herod, Wendy
    Hopyan, Julia
    Machnowska, Matylda
    Maggisano, Robert
    Aviv, Richard
    Fox, Allan J.
    Carotid near-occlusion can be identified with ultrasound by low flow velocity distal to the stenosis2019In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 60, no 3, p. 396-404Article in journal (Refereed)
    Abstract [en]

    Background: Most carotid near-occlusions are indistinguishable from conventional >= 50% stenosis on ultrasound, demonstrating high peak systolic velocity (PSV) in the stenosis. Purpose To study whether the velocity distal to the stenosis can separate high PSV near-occlusion from conventional >= 50% stenosis.

    Material and Methods: We included patients with >= 50% carotid stenosis with high PSV (>= 125 cm/s), examined with both computed tomography angiography (CTA) and ultrasound within 30 days, and a distal velocity measurement was performed. Based on CTA, cases were divided into three groups: conventional stenosis; near-occlusion without full collapse (NwoC; normal-appearing albeit small distal artery); and near-occlusion with full collapse (NwC; threadlike distal artery). Distal Doppler ultrasound flow velocities were compared between these groups.

    Results: Sixty patients were included: 33 patients with conventional stenosis; 20 patients with NwoC; and seven patients with NwC. Mean distal PSV was 93, 63, and 21 cm/s (P < 0.001) and mean distal end-diastolic velocity was 30, 24, and 5 cm/s (P < 0.001), respectively. A distal PSV < 50 cm/s was 63% sensitive and 94% specific for separating both types of near-occlusion from conventional stenosis.

    Conclusion: In high PSV carotid stenoses, the distal velocity was lower in near-occlusions than conventional carotid stenosis. Distal velocities warrant further investigation in diagnostic studies.

  • 117.
    Johansson, Elias
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Fox, A. J.
    Carotid Near-Occlusion: A Comprehensive Review, Part 1 - Definition, Terminology, and Diagnosis2016In: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 37, no 1, p. 2-10Article, review/survey (Refereed)
    Abstract [en]

    Carotid near-occlusion is distal ICA luminal collapse beyond a tight stenosis, where the distal lumen should not be used for calculating percentage stenosis. Near-occlusion with full ICA collapse is well-known, with a threadlike lumen. However, near-occlusion without collapse is often subtle and can be overlooked as a usual severe stenosis. More than 10 different terms have been used to describe near-occlusion, sometimes causing confusion. This systematic review presents what is known about carotid near-occlusion. In this first part, the foci are definition, terminology, and diagnosis.

  • 118.
    Johansson, Elias
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Fox, A. J.
    Carotid Near-Occlusion: A Comprehensive Review, Part 2 - Prognosis and Treatment, Pathophysiology, Confusions, and Areas for Improvement2016In: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 37, no 2, p. 200-204Article, review/survey (Refereed)
    Abstract [en]

    Carotid near-occlusion is distal luminal collapse of the internal carotid artery beyond a tight stenosis. Part 2 of this systematic review focuses on prognosis and treatment and pathophysiology. Areas of confusion regarding terminology, diagnosis, and prognosis are also covered. SUMMARY: In Part 1 of this review, the definition, terminology, and diagnosis of carotid near-occlusion were presented. Carotid near-occlusions (all types) showed a lower risk of stroke than other severe stenoses. However, emerging evidence suggests that the near-occlusion prognosis with full collapse (higher risk) differs from that without full collapse (lower risk). This systematic review presents what is known about carotid near-occlusion. In this second part, the foci are prognosis and treatment, pathophysiology, the current confusion about near-occlusion, and areas in need of future improvement.

  • 119.
    Johansson, Erik
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Andersson, Jonas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Tölli, Heikki
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Liquid ionization chamber initial recombination dependence on LET for electrons and photons2013In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 58, no 12, p. 4225-4236Article in journal (Refereed)
    Abstract [en]

    The possibility of indirect measurements of linear energy transfer (LET) with a liquid ionization chamber (LIC) has been investigated by studying initial recombination losses at different applied voltages. A linear fit is made to the voltage-signal curve and the intersection point of the fit and the voltage-axis is shown to correlate with LET. The LIC applied voltages were 100-700 V, which corresponds to electric field strengths between 0.3 and 2.0 MV m(-1). Several different photon and electron beams have been studied, and by using MCNPX (TM) the respective LET spectra have been determined. The beam qualities in this study were found to have a fluence averaged LET between 0.17 and 1.67 keV mu m(-1) and a corresponding dose averaged LET between 0.97 and 4.62 keV mu m(-1). For the experimental data in this study the linear fit method yields consistent results with respect to Monte Carlo simulated LET values. A calibration curve for LET determination is provided for the LIC used in the present work.

  • 120. Johansson, Karl-Axel
    et al.
    Nilsson, Per
    Zackrisson, Björn
    Ohlson, Birgitta
    Kjellén, Elisabeth
    Mercke, Claes
    Alvarez-Fonseca, Mauricio
    Billström, Anette
    Björk-Eriksson, Thomas
    Björ, Ove
    Ekberg, Lars
    Friesland, Signe
    Karlsson, Magnus
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lagerlund, Magnus
    Lundkvist, Lena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Löfroth, Per-Olov
    Löfvander-Thapper, Kerstin
    Nilsson, Alla
    Nyman, Jan
    Persson, Essie
    Reizenstein, Johan
    Rosenbrand, Hans-Olov
    Wiklund, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Wittgren, Lena
    The quality assurance process for the ARTSCAN head and neck study - A practical interactive approach for QA in 3DCRT and IMRT2008In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 87, no 2, p. 290-299Article in journal (Refereed)
    Abstract [en]

    AIM: This paper describes the quality assurance (QA) work performed in the Swedish multicenter ARTSCAN (Accelerated RadioTherapy of Squamous cell CArcinomas in the head and Neck) trial to guarantee high quality in a multicenter study which involved modern radiotherapy such as 3DCRT or IMRT.

    MATERIALS AND METHODS: The study was closed in June 2006 with 750 randomised patients. Radiation therapy-related data for every patient were sent by each participating centre to the QA office where all trial data were reviewed, analysed and stored. In case of any deviation from the protocol, an interactive process was started between the QA office and the local responsible clinician and/or physicist to increase the compliance to the protocol for future randomised patients. Meetings and workshops were held on a regular basis for discussions on various trial-related issues and for the QA office to report on updated results.

    RESULTS AND DISCUSSION: This review covers the 734 patients out of a total of 750 who had entered the study. Deviations early in the study were corrected so that the overall compliance to the protocol was very high. There were only negligible variations in doses and dose distributions to target volumes for each specific site and stage. The quality of the treatments was high. Furthermore, an extensive database of treatment parameters was accumulated for future dose-volume vs. endpoint evaluations.

    CONCLUSIONS: This comprehensive QA programme increased the probability to draw firm conclusions from our study and may serve as a concept for QA work in future radiotherapy trials where comparatively small effects are searched for in a heterogeneous tumour population.

  • 121.
    Johansson, Måns
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Patients with Alzheimer’s disease show correlation between plasma anti-HSV IgG levels and accumulation of 18F-FHBG in the lateral ventricles2018Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 122.
    Jonasson, Lars
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Boraxbekk, Carl-Johan
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR). Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark.
    Simulating effects of brain atrophy in longitudinal PET imaging with an anthropomorphic brain phantom2017In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 62, no 13, p. 5213-5227Article in journal (Refereed)
    Abstract [en]

    In longitudinal positron emission tomography (PET), the presence of volumetric changes over time can lead to an overestimation or underestimation of the true changes in the quantified PET signal due to the partial volume effect (PVE) introduced by the limited spatial resolution of existing PET cameras and reconstruction algorithms. Here, a 3D-printed anthropomorphic brain phantom with attachable striata in three sizes was designed to enable controlled volumetric changes. Using a method to eliminate the non-radioactive plastic wall, and manipulating BP levels by adding different number of events from list-mode acquisitions, we investigated the artificial volume dependence of BP due to PVE, and potential bias arising from varying BP. Comparing multiple reconstruction algorithms we found that a high-resolution ordered- subsets maximization algorithm with spatially variant point-spread function resolution modeling provided the most accurate data. For striatum, the BP changed by 0.08% for every 1% volume change, but for smaller volumes such as the posterior caudate the artificial change in BP was as high as 0.7% per 1% volume change. A simple gross correction for striatal volume is unsatisfactory, as the amplitude of the PVE on the BP differs depending on where in the striatum the change occurred. Therefore, to correctly interpret age-related longitudinal changes in the BP, we must account for volumetric changes also within a structure, rather than across the whole volume. The present 3D-printing technology, combined with the wall removal method, can be implemented to gain knowledge about the predictable bias introduced by the PVE differences in uptake regions of varying shape.

  • 123.
    Jonsson, Joakim H.
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Akhtari, Mohammad M.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Karlsson, Magnus G.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Johansson, Adam
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Asklund, Thomas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Accuracy of inverse treatment planning on substitute CT images derived from MR data for brain lesions2015In: Radiation Oncology, ISSN 1748-717X, E-ISSN 1748-717X, Vol. 10, article id 13Article in journal (Refereed)
    Abstract [en]

    Background: In this pilot study we evaluated the performance of a substitute CT (s-CT) image derived from MR data of the brain, as a basis for optimization of intensity modulated rotational therapy, final dose calculation and derivation of reference images for patient positioning. Methods: S-CT images were created using a Gaussian mixture regression model on five patients previously treated with radiotherapy. Optimizations were compared using D-max, D-min, D-median and D-mean measures for the target volume and relevant risk structures. Final dose calculations were compared using gamma index with 1%/1 mm and 3%/3 mm acceptance criteria. 3D geometric evaluation was conducted using the DICE similarity coefficient for bony structures. 2D geometric comparison of digitally reconstructed radiographs (DRRs) was performed by manual delineation of relevant structures on the s-CT DRR that were transferred to the CT DRR and compared by visual inspection. Results: Differences for the target volumes in optimization comparisons were small in general, e.g. a mean difference in both D-min and D-max within similar to 0.3%. For the final dose calculation gamma evaluations, 100% of the voxels passed the 1%/1 mm criterion within the PTV. Within the entire external volume between 99.4% and 100% of the voxels passed the 3%/3 mm criterion. In the 3D geometric comparison, the DICE index varied between approximately 0.8-0.9, depending on the position in the skull. In the 2D DRR comparisons, no appreciable visual differences were found. Conclusions: Even though the present work involves a limited number of patients, the results provide a strong indication that optimization and dose calculation based on s-CT data is accurate regarding both geometry and dosimetry.

  • 124.
    Jonsson, Joakim H
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Brynolfsson, Patrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Garpebring, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Söderström, Karin
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Registration accuracy for MR images of the prostate using a subvolume based registration protocol2011In: Radiation Oncology, ISSN 1748-717X, E-ISSN 1748-717X, Vol. 6, no 1, p. 73-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: In recent years, there has been a considerable research effort concerning the integration of magnetic resonance imaging (MRI) into the external radiotherapy workflow motivated by the superior soft tissue contrast as compared to computed tomography. Image registration is a necessary step in many applications, e.g. in patient positioning and therapy response assessment with repeated imaging. In this study, we investigate the dependence between the registration accuracy and the size of the registration volume for a subvolume based rigid registration protocol for MR images of the prostate.

    METHODS: Ten patients were imaged four times each over the course of radiotherapy treatment using a T2 weighted sequence. The images were registered to each other using a mean square distance metric and a step gradient optimizer for registration volumes of different sizes. The precision of the registrations was evaluated using the center of mass distance between the manually defined prostates in the registered images. The optimal size of the registration volume was determined by minimizing the standard deviation of these distances.

    RESULTS: We found that prostate position was most uncertain in the anterior-posterior (AP) direction using traditional full volume registration. The improvement in standard deviation of the mean center of mass distance between the prostate volumes using a registration volume optimized to the prostate was 3.9 mm (p < 0.001) in the AP direction. The optimum registration volume size was 0 mm margin added to the prostate gland as outlined in the first image series.

    CONCLUSIONS: Repeated MR imaging of the prostate for therapy set-up or therapy assessment will both require high precision tissue registration. With a subvolume based registration the prostate registration uncertainty can be reduced down to the order of 1 mm (1 SD) compared to several millimeters for registration based on the whole pelvis.

  • 125.
    Jonsson, Joakim H
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Garpebring, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Magnus G
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Internal fiducial markers and susceptibility effects in MRI: simulation and measurement of spatial accuracy2012In: International Journal of Radiation Oncology, Biology, Physics, ISSN 0360-3016, E-ISSN 1879-355X, Vol. 82, no 5, p. 1612-1618Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: It is well-known that magnetic resonance imaging (MRI) is preferable to computed tomography (CT) in radiotherapy target delineation. To benefit from this, there are two options available: transferring the MRI delineated target volume to the planning CT or performing the treatment planning directly on the MRI study. A precondition for excluding the CT study is the possibility to define internal structures visible on both the planning MRI and on the images used to position the patient at treatment. In prostate cancer radiotherapy, internal gold markers are commonly used, and they are visible on CT, MRI, x-ray, and portal images. The depiction of the markers in MRI are, however, dependent on their shape and orientation relative the main magnetic field because of susceptibility effects. In the present work, these effects are investigated and quantified using both simulations and phantom measurements.

    METHODS AND MATERIALS: Software that simulated the magnetic field distortions around user defined geometries of variable susceptibilities was constructed. These magnetic field perturbation maps were then reconstructed to images that were evaluated. The simulation software was validated through phantom measurements of four commercially available gold markers of different shapes and one in-house gold marker.

    RESULTS: Both simulations and phantom measurements revealed small position deviations of the imaged marker positions relative the actual marker positions (<1 mm).

    CONCLUSION: Cylindrical gold markers can be used as internal fiducial markers in MRI.

  • 126.
    Jonsson, Joakim H
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Magnus G
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Treatment planning using MRI data: an analysis of the dose calculation accuracy for different treatment regions2010In: Radiation Oncology, ISSN 1748-717X, E-ISSN 1748-717X, Vol. 5, p. 62-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Because of superior soft tissue contrast, the use of magnetic resonance imaging (MRI) as a complement to computed tomography (CT) in the target definition procedure for radiotherapy is increasing. To keep the workflow simple and cost effective and to reduce patient dose, it is natural to strive for a treatment planning procedure based entirely on MRI. In the present study, we investigate the dose calculation accuracy for different treatment regions when using bulk density assignments on MRI data and compare it to treatment planning that uses CT data.

    METHODS: MR and CT data were collected retrospectively for 40 patients with prostate, lung, head and neck, or brain cancers. Comparisons were made between calculations on CT data with and without inhomogeneity corrections and on MRI or CT data with bulk density assignments. The bulk densities were assigned using manual segmentation of tissue, bone, lung, and air cavities.

    RESULTS: The deviations between calculations on CT data with inhomogeneity correction and on bulk density assigned MR data were small. The maximum difference in the number of monitor units required to reach the prescribed dose was 1.6%. This result also includes effects of possible geometrical distortions.

    CONCLUSIONS: The dose calculation accuracy at the investigated treatment sites is not significantly compromised when using MRI data when adequate bulk density assignments are made. With respect to treatment planning, MRI can replace CT in all steps of the treatment workflow, reducing the radiation exposure to the patient, removing any systematic registration errors that may occur when combining MR and CT, and decreasing time and cost for the extra CT investigation.

  • 127.
    Jonsson, Joakim
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Johansson, Adam
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Söderström, Karin
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Asklund, Thomas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Treatment planning of intracranial targets on MRI derived substitute CT data2013In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 108, no 1, p. 118-122Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The use of magnetic resonance imaging (MRI) as a complement to computed tomography (CT) in the target definition procedure for radiotherapy is increasing. To eliminate systematic uncertainties due to image registration, a workflow based entirely on MRI may be preferable. In the present pilot study, we investigate dose calculation accuracy for automatically generated substitute CT (s-CT) images of the head based on MRI. We also produce digitally reconstructed radiographs (DRRs) from s-CT data to evaluate the feasibility of patient positioning based on MR images. METHODS AND MATERIALS: Five patients were included in the study. The dose calculation was performed on CT, s-CT, s-CT data without inhomogeneity correction and bulk density assigned MRI images. Evaluation of the results was performed using point dose and dose volume histogram (DVH) comparisons, and gamma index evaluation. RESULTS: The results demonstrate that the s-CT images improves the dose calculation accuracy compared to the method of non-inhomogeneity corrected dose calculations (mean improvement 2.0 percentage points) and that it performs almost identically to the method of bulk density assignment. The s-CT based DRRs appear to be adequate for patient positioning of intra-cranial targets, although further investigation is needed on this subject. CONCLUSIONS: The s-CT method is very fast and yields data that can be used for treatment planning without sacrificing accuracy.

  • 128.
    Jonsson, Joanne
    et al.
    Umeå University, Faculty of Medicine, Department of Nursing.
    Magnusson, Joakim
    Umeå University, Faculty of Medicine, Department of Nursing.
    Kvinnors upplevelser av mammografi2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bakgrund: Bröstcancer är den allra vanligaste cancerformen hos kvinnor. I Sverige drabbas omkring 8000 kvinnor av denna sjukdom varje år och cirka 1500 avlider. Från och med 1986 erbjuds alla kvinnor mellan 40-74 år att delta i regelbundna mammografikontroller. Det har gjort att allt fler kvinnor diagnostiseras tidigt i sjukdomsförloppet och att antalet dödsfall reducerats. Trots fördelarna med mammografi upplever många kvinnor undersökningen som smärtsam och påfrestande. Det är därför viktigt att få en ökad förståelse för kvinnors upplevelser för att på så sätt skapa en förutsättning för ökat välbefinnande.

    Syfte: Syftet med litteraturstudien var att belysa kvinnors upplevelse i samband med mammografiscreening.

    Metod: Litteraturstudien baserades på 8 vetenskapliga artiklar. Sökningen av artiklar gjordes i databaserna CINAHL och PsychINFO. Artiklarna granskades och analyserades av författarna innan ett resultat sammanställdes.

    Resultat: Resultatet visade att tidigare erfarenheter påverkade attityderna kring mammografiscreening. Majoriteten fann undersökningen smärtsam och att bemötandet av personalen var en viktig aspekt som påverkade upplevelsen. Det visade sig att det fanns ett genomgående behov av information kring undersökningen samt att väntan på resultatet var en tid fylld med oro och ovisshet.

    Slutsats: Trots att många kvinnor upplever fysiska såväl som psykiska obehag i samband med mammografi är de motiverade att fortsätta medverka i screeningundersökningar. Med anledning av detta är det viktigt för röntgensjuksköterskan att ha en förståelse och kunskap om kvinnors upplevelser så det finns möjlighet att motverka dessa obehag så långt det är möjligt.

  • 129. Jäderling, Fredrik
    et al.
    Nyberg, Tommy
    Öberg, Michael
    Carlsson, Stefan
    Skorpil, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Department of Radiology, Uppsala University Hospital, Uppsala, Sweden.
    Blomqvist, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Department of Radiology, Karolinska University Hospital, Solna, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
    Accuracy in local staging of prostate cancer by adding a three-dimensional T2-weighted sequence with radial reconstructions in magnetic resonance imaging2018In: Acta radiologica open, E-ISSN 2058-4601, Vol. 7, no 2Article in journal (Refereed)
    Abstract [en]

    Background: The evidence supporting the use of magnetic resonance imaging (MRI) in prostate cancer detection has been established, but its accuracy in local staging is questioned. Purpose: To investigate the additional value of multi-planar radial reconstructions of a three-dimensional (3D) T2-weighted (T2W) MRI sequence, intercepting the prostate capsule perpendicularly, for improving local staging of prostate cancer. Material and Methods: Preoperative, bi-parametric prostate MRI examinations in 94 patients operated between June 2014 and January 2015 where retrospectively reviewed by two experienced abdominal radiologists. Each patient was presented in two separate sets including diffusion-weighted imaging, without and with the 3D T2W set that included radial reconstructions. Each set was read at least two months apart. Extraprostatic tumor extension (EPE) was assessed according to a 5-point grading scale. Sensitivity and specificity for EPE was calculated and presented as receiver operating characteristics (ROC) with area under the curve (AUC), using histology from whole-mount prostate specimen as gold standard. Inter-rater agreement was calculated for the two different reading modes using Cohen's kappa. Results: The AUC for detection of EPE for Readers 1 and 2 in the two-dimensional (2D) set was 0.70 and 0.68, respectively, and for the 2D+3D set 0.62 and 0.65, respectively. Inter-rater agreement (Reader 1 vs. Reader 2) on EPE using Cohen's kappa for the 2D and 2D+3D set, respectively, was 0.42 and 0.17 (i.e. moderate and poor agreement, respectively). Conclusion: The addition of 3D T2W MRI with radial reconstructions did not improve local staging in prostate cancer.

  • 130.
    Kaboodvand, Neda
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Bäckman, Lars
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Salami, Alireza
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    The retrosplenial cortex: a memory gateway between the cortical default mode network and the medial temporal lobe2018In: Human Brain Mapping, ISSN 1065-9471, E-ISSN 1097-0193, Vol. 39, no 5, p. 2020-2034Article in journal (Refereed)
    Abstract [en]

    The default mode network (DMN) involves interacting cortical areas, including the posterior cingulate cortex (PCC) and the retrosplenial cortex (RSC), and subcortical areas, including the medial temporal lobe (MTL). The degree of functional connectivity (FC) within the DMN, particularly between MTL and medial-parietal subsystems, relates to episodic memory (EM) processes. However, past resting-state studies investigating the link between posterior DMN-MTL FC and EM performance yielded inconsistent results, possibly reflecting heterogeneity in the degree of connectivity between MTL and specific cortical DMN regions. Animal work suggests that RSC has structural connections to both cortical DMN regions and MTL, and may thus serve as an intermediate layer that facilitates information transfer between cortical and subcortical DMNs. We studied 180 healthy old adults (aged 64-68 years), who underwent comprehensive assessment of EM, along with resting-state fMRI. We found greater FC between MTL and RSC than between MTL and the other cortical DMN regions (e.g., PCC), with the only significant association with EM observed for MTL-RSC FC. Mediational analysis showed that MTL-cortical DMN connectivity increased with RSC as a mediator. Further analysis using a graph-theoretical approach on DMN nodes revealed the highest betweenness centrality for RSC, confirming that a high proportion of short paths among DMN regions pass through RSC. Importantly, the degree of RSC mediation was associated with EM performance, suggesting that individuals with greater mediation have an EM advantage. These findings suggest that RSC forms a critical gateway between MTL and cortical DMN to support EM in older adults.

  • 131.
    Kadesjö, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Olofsson, Jörgen
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    A practical approach to diode based in vivo dosimetry for intensity modulated radiotherapy2011In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 98, no 3, p. 378-381Article in journal (Refereed)
    Abstract [en]

    A method for in vivo entrance dosimetry, using point detectors, in intensity modulated radiotherapy has been clinically evaluated. Diode dosimetry was performed for treatments of the head and neck and prostate regions. The results were good; 92.2% of the measurements showed deviations within ±5% of the expected values.

  • 132.
    Kallioniemi, Antti
    et al.
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Jurvelin, Jukka
    Department of Physics, University of Kuopio, Kuopio, Finland; Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland.
    Nieminen, Miika
    Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland .
    Lammi, Mikko
    Department of Anatomy, Institute of Biomedicine, University of Kuopio, Kuopio, Finland .
    Töyräs, Juha
    Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
    Contrast agent enhanced pQCT of articular cartilage.2007In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 52, no 4, p. 1209-1219, article id 17264381Article in journal (Refereed)
    Abstract [en]

    The delayed gadolinium enhanced MRI of cartilage (dGEMRIC) technique is the only non-invasive means to estimate proteoglycan (PG) content in articular cartilage. In dGEMRIC, the anionic paramagnetic contrast agent gadopentetate distributes in inverse relation to negatively charged PGs, leading to a linear relation between T1,Gd and spatial PG content in tissue. In the present study, for the first time, contrast agent enhanced peripheral quantitative computed tomography (pQCT) was applied, analogously to dGEMRIC, for the quantitative detection of spatial PG content in cartilage. The suitability of two anionic radiographic contrast agents, gadopentetate and ioxaglate, to detect enzymatically induced PG depletion in articular cartilage was investigated. First, the interrelationships of x-ray absorption, as measured with pQCT, and the contrast agent solution concentration were investigated. Optimal contrast agent concentrations for the following experiments were selected. Second, diffusion rates for both contrast agents were investigated in intact (n=3) and trypsin-degraded (n=3) bovine patellar cartilage. The contrast agent concentration of the cartilaginous layer was measured prior to and 2-27 h after immersion. Optimal immersion time for the further experiments was selected. Third, the suitability of gadopentetate and ioxaglate enhanced pQCT to detect the enzymatically induced specific PG depletion was investigated by determining the contrast agent concentrations and uronic acid and water contents in digested and intact osteochondral samples (n=16). After trypsin-induced PG loss (-70%, p<0.05) the penetration of gadopentetate and ioxaglate increased (p<0.05) by 34% and 48%, respectively. Gadopentetate and ioxaglate concentrations both showed strong correlation (r=-0.95, r=-0.94, p<0.01, respectively) with the uronic acid content. To conclude, contrast agent enhanced pQCT provides a technique to quantify PG content in normal and experimentally degraded articular cartilage in vitro. As high resolution imaging of e.g. the knee joint is possible with pQCT, the present technique may be further developed for in vivo quantification of PG depletion in osteoarthritic cartilage. However, careful in vitro and in vivo characterization of diffusion mechanics and optimal contrast agent concentrations are needed before diagnostic applications are feasible.

  • 133.
    Karlsson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    A study of some energy dependent characteristics of X-ray screens used in diagnostic radiology: screen-film sensitivity, MTF and some related factors1983Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Fluorescent x-ray screens are used in medical x-ray diagnostics to absorb x-ray photons and convert these x-ray photons to visible light. The light distribution from these screens are then registered on photographic film to give an x-ray image. Both the sensitivity and the resolution characteristics of these systems are dependent on the x-ray photon energy. To enable a study of these and some other energy dependent characteristics of x-ray screens a number of almost monoener-getic radiation sources were constructed, tested with regard to their purity and calibrated. Both film and a photo-multiplier tube were used as light detectors.The sensitivity of screens with three different screen phosphors were studied as a function of the photon energy and large variations in sensitivity was found for different photon energies and screen phosphors. The light from the screens has been compared to the absorbed energy in the screens and this comparison shows that the energy dependence of the screens can approximately be predicted by calculations of the absorbed energy, except at low photon energies where other effects like increased light absorption in the screens is present.The modulation transfer factor (MTF) was studied both experimentally and theoretically as a function of photon energy. Two effects were shown to influence the energy dependence of the MTF. At low energies an increased light diffusion will destroy the MTF and at energies above the K-edge of the high-Z elements in the screens the production and re-absorption of K-radiation will deteriorate the MTF.Both the energy dependence of the screen-film sensitivity and the MTF have been calculated for some normally used spectral distributions from x-ray tubes and significant changes due to choice of kV and filtration of the beam were found. Other effects such as the number of interacting photons in the screens per unit area, contribution of K-radiation from one screen to the other, and light contribution to the front emulsion of the film compared to the back emulsion have also been investigated as a function of photon energy.Optimization of x-ray systems and clinical routines to give the lowest possible radiation dose to the patient with an acceptable image quality is an important task to carry out. The energy dependent characteristi es of x-ray screens studied in this work is a lead in the optimizing of the system with regard to choice of x-ray screens, film and radiation quality.

  • 134.
    Karlsson, Sari
    et al.
    Karolinska Institute.
    Rieckmann, Anna
    Karolinska Institute.
    Karlsson, Per
    Karolinska Hospital.
    Farde, Lars
    Karolinska Hospital.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Bäckman, Lars
    Karolinska Institute.
    Relationship of dopamine D1 receptor binding in striatal and extrastriatal regions to cognitive functioning in healthy humans2011In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 57, no 2, p. 346-351Article in journal (Refereed)
    Abstract [en]

    Dopamine (DA) availability in both striatal and extrastriatal brain regions has been implicated in cognitive performance. Given that different brain regions are neuroanatomically and functionally different, DA receptor binding in different brain regions may be selectively important to specific cognitive functions. Using PET and the radioligand SCH23390, we measured D1 receptor binding potential (BP(ND)) in dorsolateral prefrontal cortex (DLPFC), hippocampus (HC), as well as in sensorimotor (SMST), associative (AST), and limbic (LST) striatum in 20 healthy younger persons. Subjects completed tasks assessing executive functioning, episodic memory, speed, and general knowledge. Unlike previous reports, we found no linear or curvilinear relationships between D1 receptor binding in DLPFC and performance in any cognitive task. However, BP(ND) in HC was positively linked to executive performance as well as to speed and knowledge. With regard to the striatal subregions, D1 BP(ND) in SMST was more strongly related to speed compared to the other striatal subregions, whereas D1 BP(ND) in AST was more strongly linked to general knowledge. These findings provide support for the notion that D1 receptors in separate brain regions are differentially related to performance in tasks tapping various cognitive domains.

  • 135. Khangure, Simon R.
    et al.
    Benhabib, Hadas
    Machnowska, Matylda
    Fox, Allan J.
    Grönlund, Christer
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Herod, Wendy
    Maggisano, Robert
    Sjöberg, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Wester, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Department of Clinical Sciences, Karolinska Institutet Danderyds Hospital, Stockholm, Sweden.
    Hojjat, Seyed-Parsa
    Hopyan, Julia
    Aviv, Richard I.
    Johansson, Elias
    Carotid near-occlusion frequently has high peak systolic velocity on Doppler ultrasound2018In: Neuroradiology, ISSN 0028-3940, E-ISSN 1432-1920, Vol. 60, no 1, p. 17-25Article in journal (Refereed)
    Abstract [en]

    Purpose: Carotid near-occlusion is a tight atherosclerotic stenosis of the internal carotid artery (ICA) resulting in decrease in diameter of the vessel lumen distal to the stenosis. Near-occlusions can be classified as with or without full collapse, and may have high peak systolic velocity (PSV) across the stenosis, mimicking conventional > 50% carotid artery stenosis. We aimed to determine how frequently near-occlusions have high PSV in the stenosis and determine how accurately carotid Doppler ultrasound can distinguish high-velocity near-occlusion from conventional stenosis.

    Methods: Included patients had near-occlusion or conventional stenosis with carotid ultrasound and CT angiogram (CTA) performed within 30 days of each other. CTA examinations were analyzed by two blinded expert readers. Velocities in the internal and common carotid arteries were recorded. Mean velocity, pulsatility index, and ratios were calculated, giving 12 Doppler parameters for analysis.

    Results: Of 136 patients, 82 had conventional stenosis and 54 had near-occlusion on CTA. Of near-occlusions, 40 (74%) had high PSV (≥ 125 cm/s) across the stenosis. Ten Doppler parameters significantly differed between conventional stenosis and high-velocity near-occlusion groups. However, no parameter was highly sensitive and specific to separate the groups.

    Conclusion: Near-occlusions frequently have high PSV across the stenosis, particularly those without full collapse. Carotid Doppler ultrasound does not seem able to distinguish conventional stenosis from high-velocity near-occlusion. These findings question the use of ultrasound alone for preoperative imaging evaluation.

  • 136. Kiesel, Barbara
    et al.
    Thome, Carina M.
    Weiss, Tobias
    Jakola, Asgeir
    Darlix, Amelie
    Pellerino, Alessia
    Furtner, Julia
    Kerschbaumer, Johannes
    Weller, Michael
    Pilkington, Geoffrey
    Moyal, Elizabeth Cohen-Jonathan
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Watts, Colin
    Ruda, Roberta
    Reifenberger, Guido
    Oberg, Ingela
    Honnorat, Jerome
    Wick, Wolfgang
    Preusser, Matthias
    Widhalm, Georg
    Berghoff, Anna
    PERIOPERATIVE IMAGING OF BRAIN METASTASES: A EUROPEAN ASSOCIATION OF NEURO-ONCOLOGY (EANO) YOUNGSTERS SURVEY2018In: Neuro-Oncology, ISSN 1522-8517, E-ISSN 1523-5866, Vol. 20, p. 59-59Article in journal (Other academic)
    Abstract [en]

    BACKGROUND

    Neurosurgical resection is an important treatment option in the multimodal therapy of brain metastases (BM). Perioperative imaging is established in primary brain tumors to assess the extent of resection. However, structured guidelines on the use of perioperative imaging for BM patients are so far missing.

    METHODS

    The European Association of Neuro-Oncology (EANO) Youngsters committee designed a comprehensive questionnaire on the use of perioperative imaging. The survey was distributed to physicians with neuro-oncologic focus via the EANO and the European Association of Neurosurgical Societies (EANS) network.

    RESULTS

    120 physicians from non-European countries and European countries responded to the survey. 76/120 neurosurgeons, 18/120 radiation oncologists and 17/120 neurologists participated. 89/120 participants worked at academic hospitals and 39/40 participants worked in high patient volume centers as defined by >50 BM cases per year. Local standard operating procedures for perioperative imaging were applied by 94/120 physicians. The preferred preoperative imaging method represented MRI for 112/120 (93.3%) participants. Postsurgical imaging was routinely performed by 106/120 physicians. 77/120 participants indicated MRI as the preferred postoperative imaging method, however, only 71/120 performed postoperative MRI imaging within 72 hours after resection. No correlation of postsurgical MRI and localization at an academic hospital (58/79 [73.4%] vs. 19/27 [70.4%], p>0.05) or patient volume (49/71 [69%] vs 25/40 [62.5%], p>0.05) was evident. The most frequently indicated reason for postsurgical imaging was the assessment of extent of resection as participants indicated to adjust the radiotherapy plan or even considered re-surgery to achieve complete resection. CONCLUSIONS: This EANO survey indicates that preoperative MRI is the preferred imaging technique for the majority of physicians, whereas a high variability of postoperative neuroimaging routines including CT and MRI was observed. International guidelines for perioperative imaging with special focus on postoperative MRI are warranted in order to optimize perioperative treatment modalities for BM patients.

  • 137.
    Kjellberg, Martin
    et al.
    Department of Orthopaedics, Sundsvall Hospital, Sundsvall,l Sweden.
    Al-Amiry, Bariq
    Department of Radiology, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Englund, Erling
    Department of Research and Development, Västernorrland County, Sundsvall, Sweden.
    Sjödén, Göran O
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Sayed-Noor, Arkan S
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Measurement of leg length discrepancy after total hip arthroplasty: the reliability of a plain radiographic method compared to CT-scanogram2012In: Skeletal Radiology, ISSN 0364-2348, E-ISSN 1432-2161, Vol. 41, no 2, p. 187-191Article in journal (Refereed)
    Abstract [en]

    To measure the interobserver reliability and intraobserver reproducibility of post total hip arthroplasty (THA) leg length discrepancy (LLD) measurement on radiographs as well as to evaluate its accuracy by comparing it with LLD measurement on computed tomographic scanogram (CT-scanogram). In this prospective study, postoperative LLD measurements in ten THA patients were made by four observers on anteroposterior radiographs of the pelvis (inter-teardrop line to the tip of lesser trochanter) and compared to LLD measurements made on CT-scanogram scout views of the lower limb. Two observers repeated the LLD measurements on radiographs 8 weeks after the first measurements. The interobserver reliability of the LLD measurement on plain radiographs was evaluated by comparing the measurements of the four observers and the intraobserver reproducibility by comparing the two repeated measurements made by the two observers. We found excellent interobserver reliability (mean ICC 0.83) and intraobserver reproducibility (ICC 0.90 and 0.88) of the LLD measurements on plain radiographs. There was a moderate to excellent agreement, but with wide variation of measurements among the four observers, when plain radiographic measurement was compared with CT-scanogram (ICC 0.58, 0.60, 0.71, and 0.82). Despite the excellent interobserver reliability and intraobserver reproducibility of LLD measurement on radiographs, clinicians should be aware of its limited accuracy when compared to CT-scanogram.

  • 138.
    Kockum, Karin
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Lilja-Lund, Otto
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Larsson, E. -M
    Rosell, M.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Söderström, L.
    Virhammar, J.
    Laurell, Katarina
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    The idiopathic normal-pressure hydrocephalus Radscale: a radiological scale for structured evaluation2018In: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 25, no 3, p. 569-576Article in journal (Refereed)
    Abstract [en]

    Background and purpose: Despite the important role of imaging in diagnosing idiopathic normal‐pressure hydrocephalus (iNPH), a structured overall assessment of radiological signs is still lacking. The purpose of this study was to construct a radiological scale, composed of morphological signs of iNPH, and compare it with clinical symptoms.

    Methods: In this prospective, population‐based study of iNPH, 168 individuals (93 females) [mean age 75 (range 66–92) years] underwent computed tomography of the brain and a neurological examination with assessment of clinical symptoms according to Hellström's iNPH scale. Two radiologists, blinded to clinical data, independently evaluated and measured eight radiological parameters, i.e. Evans’ index, callosal angle, size of temporal horns, narrow high‐convexity sulci, dilated Sylvian fissures, focally dilated sulci, peri‐ventricular hypodensities and bulging of the lateral ventricular roof.

    Results: In a linear regression model, all parameters except ventricular roof bulging were significantly associated with clinical iNPH symptoms. The seven remaining parameters were summarized into a total iNPH Radscale score ranging from 0 to 12. There was a significant correlation (r = 0.55, < 0.001) between the total iNPH Radscale score and clinical symptoms. The inter‐rater agreement for the included radiological parameters was high (intraclass correlation, 0.74–0.97).

    Conclusion: The iNPH Radscale may become a valuable diagnostic screening tool, allowing a structured radiological assessment. A high iNPH Radscale score together with clinical symptoms should raise suspicion of iNPH, motivating further evaluation for shunt surgery.

  • 139. Kruse, J.
    et al.
    Lehto, N.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Tegner, Y.
    Engström, A.
    Scrutinized with inadequate control and support: Interns' experiences communicating with and writing referrals to hospital radiology departments - A qualitative study2016In: Radiography, ISSN 1078-8174, E-ISSN 1532-2831, Vol. 22, no 4, p. 313-318Article in journal (Refereed)
    Abstract [en]

    Introduction: Interns' experiences communicating with and writing referrals to hospital radiology departments are important for patient safety, image quality, and decision-making in the diagnostic process. Understanding roles within the department and in the diagnostic process is important for communication. This study aimed to describe interns' experiences communicating with and writing referrals to their hospital's radiology department. Method: A qualitative study design was used. Data was collected from focus discussions with ten interns in three focus groups in Northern Sweden during 2012. The data were subjected to qualitative content analysis. Results: One theme, "a feeling of being scrutinized and lacking control", was identified in the final categories. The interns experienced that the radiology department placed high demands on them and desired more diagnostic skills training, resources and feedback. The interns suggested the following improvements: enhanced dialogue and feedback, improved education, handy guidelines, and practice writing referrals. Conclusion: Interns need more feedback from, and dialogue with, members of the Department of Radiology. They also need more knowledge of referral guidelines, appropriateness criteria and more practice to develop their knowledge and skill for writing referrals. They describe feelings of inadequate support and feel scrutinized in demanding work conditions and need more collaboration. They also need more time and more control of radiology outcomes, and they are eager to learn. 

  • 140. Kuess, Peter
    et al.
    Andrzejewski, Piotr
    Nilsson, David
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Georg, Petra
    Knoth, Johannes
    Susani, Martin
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Helbich, Thomas H.
    Polanec, Stephan H.
    Georg, Dietmar
    Nyholm, Tufve
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
    Association between pathology and texture features of multi parametric MRI of the prostate2017In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 62, no 19, p. 7833-7854Article in journal (Refereed)
    Abstract [en]

    The role of multi-parametric (mp)MRI in the diagnosis and treatment of prostate cancer has increased considerably. An alternative to visual inspection of mpMRI is the evaluation using histogram-based (first order statistics) parameters and textural features (second order statistics). The aims of the present work were to investigate the relationship between benign and malignant sub-volumes of the prostate and textures obtained from mpMR images. The performance of tumor prediction was investigated based on the combination of histogram-based and textural parameters. Subsequently, the relative importance of mpMR images was assessed and the benefit of additional imaging analyzed. Finally, sub-structures based on the PI-RADS classification were investigated as potential regions to automatically detect maligned lesions. Twenty-five patients who received mpMRI prior to radical prostatectomy were included in the study. The imaging protocol included T2, DWI, and DCE. Delineation of tumor regions was performed based on pathological information. First and second order statistics were derived from each structure and for all image modalities. The resulting data were processed with multivariate analysis, using PCA (principal component analysis) and OPLS-DA (orthogonal partial least squares discriminant analysis) for separation of malignant and healthy tissue. PCA showed a clear difference between tumor and healthy regions in the peripheral zone for all investigated images. The predictive ability of the OPLS-DA models increased for all image modalities when first and second order statistics were combined. The predictive value reached a plateau after adding ADC and T2, and did not increase further with the addition of other image information. The present study indicates a distinct difference in the signatures between malign and benign prostate tissue. This is an absolute prerequisite for automatic tumor segmentation, but only the first step in that direction. For the specific identified signature, DCE did not add complementary information to T2 and ADC maps.

  • 141.
    Kulmala, Katariina
    et al.
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Karjalainen, Hannu
    Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Kokkonen, Harri
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Tiitu, Virpi
    Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Kovanen, Vuokko
    Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
    Lammi, Mikko
    Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Jurvelin, Jukka
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Korhonen, Rami
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Töyräs, Juha
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
    Diffusion of ionic and non-ionic contrast agents in articular cartilage with increased cross-linking: contribution of steric and electrostatic effects2013In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 35, no 10, p. 1415-20Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To investigate the effect of threose-induced collagen cross-linking on diffusion of ionic and non-ionic contrast agents in articular cartilage.

    DESIGN: Osteochondral plugs (Ø=6mm) were prepared from bovine patellae and divided into two groups according to the contrast agent to be used in contrast enhanced computed tomography (CECT) imaging: (I) anionic ioxaglate and (II) non-ionic iodixanol. The groups I and II contained 7 and 6 sample pairs, respectively. One of the paired samples served as a reference while the other was treated with threose to induce collagen cross-linking. The equilibrium partitioning of the contrast agents was imaged after 24h of immersion. Fixed charge density (FCD), water content, contents of proteoglycans, total collagen, hydroxylysyl pyridinoline (HP), lysyl pyridinoline (LP) and pentosidine (Pent) cross-links were determined as a reference.

    RESULTS: The equilibrium partitioning of ioxaglate (group I) was significantly (p=0.018) lower (-23.4%) in threose-treated than control samples while the equilibrium partitioning of iodixanol (group II) was unaffected by the threose-treatment. FCD in the middle and deep zones of the cartilage (p<0.05) and contents of Pent and LP (p=0.001) increased significantly due to the treatment. However, the proteoglycan concentration was not systematically altered after the treatment. Water content was significantly (-3.5%, p=0.007) lower after the treatment.

    CONCLUSIONS: Since non-ionic iodixanol showed no changes in partition after cross-linking, in contrast to anionic ioxaglate, we conclude that the cross-linking induced changes in charge distribution have greater effect on diffusion compared to the cross-linking induced changes in steric hindrance.

  • 142.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Current perspectives on cartilage and chondrocyte mechanobiology.2004In: Biorheology, ISSN 0006-355X, E-ISSN 1878-5034, Vol. 41, no 3-4, p. 593-596, article id 15299289Article, review/survey (Refereed)
    Abstract [en]

    It is well known that physiological forces are essential for the maintenance of normal composition and structure of articular cartilage. Although some of the mechanisms of mechanotransduction are known today, there are certainly many others left unrevealed. In order to understand the complicated systems present in articular cartilage, we have to bring together the data from all fields of cartilage mechanobiology. The 3rd Symposium on Mechanobiology of Cartilage and Chondrocyte was a good effort towards that goal.

  • 143.
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Corrections for improved quantitative accuracy in SPECT and planar scintigraphic imaging2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A quantitative evaluation of single photon emission computed tomography (SPECT) and planar scintigraphic imaging may be valuable for both diagnostic and therapeutic purposes. For an accurate quantification it is usually necessary to correct for attenuation and scatter and in some cases also for septal penetration. For planar imaging a background correction for the contribution from over- and underlying tissues is needed. In this work a few correction methods have been evaluated and further developed. Much of the work relies on the Monte Carlo method as a tool for evaluation and optimisation.

    A method for quantifying the activity of I-125 labelled antibodies in a tumour inoculated in the flank of a mouse, based on planar scintigraphic imaging with a pin-hole collimator, has been developed and two different methods for background subtraction have been compared. The activity estimates of the tumours were compared with measurements in vitro.

    The major part of this work is attributed to SPECT. A method for attenuation and scatter correction of brain SPECT based on computed tomography (CT) images of the same patient has been developed, using an attenuation map calculated from the CT image volume. The attenuation map is utilised not only for attenuation correction, but also for scatter correction with transmission dependent convolution subtraction (TDCS). A registration method based on fiducial markers, placed on three chosen points during the SPECT examination, was evaluated.

    The scatter correction method, TDCS, was then optimised for regional cerebral blood flow (rCBF) SPECT with Tc-99m, and was also compared with a related method, convolution scatter subtraction (CSS). TDCS has been claimed to be an iterative technique. This requires however some modifications of the method, which have been demonstrated and evaluated for a simulation with a point source.

    When the Monte Carlo method is used for evaluation of corrections for septal penetration, it is important that interactions in the collimator are taken into account. A new version of the Monte Carlo program SIMIND with this capability has been evaluated by comparing measured and simulated images and energy spectra. This code was later used for the evaluation of a few different methods for correction of scatter and septal penetration of I-123 brain SPECT. The methods were CSS, TDCS and a method where correction for scatter and septal penetration are included in the iterative reconstruction. This study shows that quantitative accuracy in I-123 brain SPECT benefits from separate modelling of scatter and septal penetration.

  • 144.
    Larsson, Anne
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Holmberg, Daniel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Sundström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Optimal contrast as a function of noise for Butterworth filtering of 111 In-pentetreotide SPECT when using model-based compensation2013In: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC), 2013Conference paper (Refereed)
    Abstract [en]

    In 111 In-pentetreotide SPECT, it can be difficult to detect small tumors because of low spatial resolution and high noise levels. For an efficient cancer treatment, it is however important to detect the tumors at an early stage. The aim of this study was to perform optimization of Butterworth post-filtering of In-111-pentetreotide SPECT, with regard to small tumor detection in the liver. All images were reconstructed with model-based OSEM reconstruction. Two collimators are evaluated, the extended low-energy general-purpose (ELEGP) and the medium-energy general-purpose (MEGP) collimator. The raw-data projection images are produced using Monte Carlo simulations of an anthropomorphic phantom with realistic In-111-pentetreotide uptake, including seven spherical tumors in the liver. Evaluation was performed using tumor contrast as a function of background noise. According to the results, the detection of the smallest tumors is facilitated by not applying a filter. For somewhat larger tumors, a Butterworth filter of critical frequencies of 0.5-0.6 cm(-1) and an order of 10-12 is more appropriate. ELEGP proved to be better than MEGP for small tumor detection. The study is a continuation of a previous project where collimator choice, acquisition time, number of projection angles and OSEM settings were studied for the same geometry.

  • 145.
    Larsson, Anne
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Jakobson Mo, Susanna
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Rotation radius dependence of 123I-FP-CIT and 123I-IBZM SPECT uptake ratios: a Monte Carlo study2012In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 40, no 4, p. 249-254Article in journal (Refereed)
    Abstract [en]

    In dopamine brain SPECT, semiquantitative techniques are in use, mostly for research purposes, to calculate activity uptake in the striatum relative to the background. The measured uptake ratios depend on both acquisition and reconstruction, and one important parameter is the rotation radius of the γ-camera detectors, which affects spatial resolution. In brain SPECT research studies, the rotation radius is typically set to a constant value to maintain a constant resolution, but because of variations in patient anatomy and compliance, this is not always possible.

    METHODS: In this study, correction factors as a function of rotation radius are developed to correct the uptake ratios where the rotation radius has deviated from the reference value, 15 cm. Monte Carlo simulations of a digital brain phantom were used to produce images with a high and a low uptake ratio, and for both studies the rotation radius was varied between 14 and 23 cm. Two different methods, one based on 2-dimensional (2D) regions of interest of constant shape and size, and one based on predefined 3-dimensional (3D) volumes of interest, were used to calculate the semiquantitative uptake ratios.

    RESULTS: For the 2D method, the change in uptake ratio was 1.2%/cm for the high uptake ratio and 0.9%/cm for the low uptake ratio. The corresponding results for the 3D method were 2.1% and 1.7%, respectively.

    CONCLUSION: The 3D method was found to be more dependent on rotation radius than the 2D method, which was expected because of the 3D nature of the partial-volume effect. The correction factors were, however, less dependent on which of the 2 uptake ratios was simulated, which is positive for the application of the correction equations on patient data.

  • 146. Leide-Svegborn, Sigrid
    et al.
    Ahlgren, Lars
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Mattsson, Sören
    Excretion of radionuclides in human breast milk after nuclear medicine examinations. Biokinetic and dosimetric data and recommendations on breastfeeding interruption2016In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 43, no 5, p. 808-821Article in journal (Refereed)
    Abstract [en]

    Purpose To review early recommendations and propose guidelines for breastfeeding interruption after administration of radiopharmaceuticals, based on additional biokinetic and dosimetric data.

    Methods Activity concentrations in breast milk from 53 breastfeeding patients were determined. The milk was collected at various times after administration of 16 different radiopharmaceuticals. The fraction of the activity administered to the mother excreted in the breast milk, the absorbed doses to various organs and tissues and the effective dose to the infant were estimated.

    Results The fraction of the administered activity excreted per millilitre of milk varied widely from 10(-10) to 10(-3) MBq/MBq administered. For Tc-99m-labelled radiopharmaceuticals, the total fraction of the administered activity excreted in the milk varied from 0.0057 % for Tc-99m-labelled red blood cells (RBC) to 19 % for Tc-99m-pertechnetate. The effective dose to an infant per unit activity administered to the mother ranged from 6.7 x 10(-6) mSv/MBq for Tc-99m-labelled RBC to 3.6 x 10(-2) mSv/MBq for Tc-99m-pertechnetate. For the other radiopharmaceuticals, the total fraction of administered activity excreted in the milk varied from 0.018 % (Cr-51-EDTA) to 48 % (I-131-NaI). The effective dose ranged from 5.6 x 10(-5) mSv(infant)/MBq(mother) (Cr-51-EDTA) to 106 mSv(infant)/MBq(mother) (I-131-NaI).

    Conclusions Based on an effective dose limit of 1 mSv to the infant and a typical administered activity, we recommend cessation of breastfeeding for I-131-NaI and interruption of feeding for 12 h for I-125-iodohippurate, I-131-iodohippurate, Tc-99m-pertechnetate and Tc-99m-MAA. During this 12-h period all breast milk should be expressed at least three times and discarded. For the other radiopharmaceuticals included in this study, no interruption of breastfeeding is necessary.

  • 147.
    Lenfeldt, Niklas
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology. Neurologi.
    Andersson, Nina
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Ågren-Wilsson, Aina
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology. Neurologi.
    Bergenheim, A Tommy
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery. Neurokirurgi.
    Koskinen, Lars-Owe D
    Neurokirurgi.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology. Neurologi.
    Cerebrospinal fluid pulse pressure method: a possible substitute for the examination of B waves2004In: Journal of Neurosurgery, ISSN 0022-3085, E-ISSN 1933-0693, Vol. 101, no 6, p. 944-950Article in journal (Refereed)
    Abstract [en]

    Object. The appearance of numerous B waves during intracranial pressure (ICP) registration in patients with idiopathic adult hydrocephalus syndrome (IAHS) is considered to predict good outcome after shunt surgery. The aim of this study was to describe which physical parameters of the cerebrospinal fluid (CSF) system B-waves reflect and to find a method that could replace long-term B-wave analysis.

    Methods. Ten patients with IAHS were subjected to long-term registration of ICP and a lumbar constant-pressure infusion test. The B-wave presence, CSF outflow resistance (Rout), and relative pulse pressure coefficient (RPPC) were assessed using computerized analysis. The RPPC was introduced as a parameter reflecting the joint effect of elastance and pulsatory volume changes on ICP and was determined by relating ICP pulse amplitudes to mean ICP.

    Conclusions. The B-wave presence on ICP registration correlates strongly with RPPC (r = 0.91, p < 0.001, 10 patients) but not with CSF Rout. This correlation indicates that B waves—like RPPC—primarily reflect the ability of the CSF system to reallocate and store liquid rather than absorb it. The RPPC-assessing lumbar short-term CSF pulse pressure method could replace the intracranial long-term B-wave analysis.

  • 148.
    Levring Jäghagen, Eva
    Umeå University, Faculty of Medicine, Department of Odontology, Oral and Maxillofacial Radiology.
    Svalgfunktionen: videoradiografisk undersökning under sväljning och tal2009In: Tandläkartidningen, ISSN 0039-6982, Vol. 101, no 1, p. 68-78Article in journal (Other academic)
  • 149.
    Levring Jäghagen, Eva
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Nilsson, M E
    Isberg, A
    Umeå University, Faculty of Medicine, Department of Odontology.
    Persisting dysphagia after uvulopalatoplasty performed with steel scalpel.1999In: The Laryngoscope, ISSN 0023-852X, E-ISSN 1531-4995, Vol. 109, no 1, p. 86-90Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES/HYPOTHESIS: The aim of the present study was to determine the incidence of postoperative persisting dysphagia after uvulopalatoplasty performed with conventional steel scalpel (UPP) and to videoradiographically evaluate the oral and pharyngeal phases of swallowing in patients reporting persisting dysphagia. The hypothesis to be tested was that patients treated with UPP would demonstrate a lower incidence of persisting dysphagia than previously found after uvulopalatoplasty performed with laser technique (LUPP).

    STUDY DESIGN: Retrospective.

    METHODS: Sixty-eight of 76 consecutive patients treated with UPP answered a questionnaire concerning outcome and late complications after the operation. The patients who reported postoperative dysphagia were additionally interviewed at a minimum of 1 year postoperatively, and the oral and pharyngeal phases of swallowing were videoradiographically examined in those with persisting dysphagia.

    RESULTS: The incidence of persisting dysphagia after UPP was 29%. Videoradiographically 71% of the dysphagic patients showed a deviant pharyngeal swallowing pattern.

    CONCLUSION: The incidence of persisting dysphagia after UPP did not differ from that reported after laser uvulopalatoplasty. Dysphagia after UPP was mostly associated with videoradiographic signs of deviant pharyngeal swallowing function. Patients should be informed that there is a risk of developing dysphagia after uvulopalatoplasty.

  • 150.
    Li, Wenrong
    et al.
    Department of Medical Imaging, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China;School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, China.
    Hirvasniemi, Jukka
    Center for Machine Vision and Signal Analysis, Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland.
    Guo, Xiong
    School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, China.
    Saarakkala, Simo
    Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland; Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland; Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland.
    Lammi, Mikko
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, P. R. China.
    Qu, Chengjuan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Comparison of bone texture between normal individuals and patients with Kashin-Beck disease from plain radiographs in knee2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 17510Article in journal (Refereed)
    Abstract [en]

    To compare tibial bone texture between Kashin-Beck disease (KBD) patients and normal individuals from plain radiographs using an advanced image analysis. Plain knee radiographs were obtained from KBD patients (n = 49) and age-matched healthy controls (n = 98). KBD were graded with diagnostic criteria WS/T 207-2010. The textural values related to bone structure from medial and lateral tibial subchondral and trabecular bones were evaluated using entropy of Laplacian-based image (ELap), entropy of local binary patterns (ELBP), homogeneity indices (HI) of local angles (HIMean, HIPerp and HIParal), and fractal dimensions from horizontal (FDHor) and vertical (FDVer) structures. KBD patients were shorter in height and lighter in weight, and their tibial width was wider than controls. Anatomical angle of KBD patients showed more genu valgus. Total KBD patients and subgroups had higher ELap, HIMean, HIPerp and HIParal in detected tibial subchondral and trabecular bones than controls, except ELap in lateral subchondral bone. ELBP, FDHor and FDVer from the detected tibial bone in KBD patients and subgroups were lower than controls, except FDVer in lateral trabecular bone. Our results indicate that micro-scale in bone texture in KBD-affected knees can be quantitatively examined from plain radiographs using an advanced image analysis.

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