| 1. |
- Agn, Mikael, et al.
(författare)
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A modality-adaptive method for segmenting brain tumors and organs-at-risk in radiation therapy planning
- 2019
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Ingår i: Medical Image Analysis. - : Elsevier BV. - 1361-8415. ; 54, s. 220-237
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a method for simultaneously segmenting brain tumors and an extensive set of organs-at-risk for radiation therapy planning of glioblastomas. The method combines a contrast-adaptive generative model for whole-brain segmentation with a new spatial regularization model of tumor shape using convolutional restricted Boltzmann machines. We demonstrate experimentally that the method is able to adapt to image acquisitions that differ substantially from any available training data, ensuring its applicability across treatment sites; that its tumor segmentation accuracy is comparable to that of the current state of the art; and that it captures most organs-at-risk sufficiently well for radiation therapy planning purposes. The proposed method may be a valuable step towards automating the delineation of brain tumors and organs-at-risk in glioblastoma patients undergoing radiation therapy.
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| 2. |
- Fällmar, David, 1980-
(författare)
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Visual assessment of perfusion and metabolism in neurodegenerative dementia
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A worldwide demographic shift is currently occurring, with rapidly increasing numbers of elderly individuals. Since the incidence of neurodegenerative disease generally increases with age, this entails an increase in dementia prevalence. There are several strong incentives for establishing robust and widely available imaging methods for the early diagnosis of these diseases. Atrophy patterns are evident only late in the disease process, and the distinction from healthy ageing can often be elusive. For early diagnosis, physiologic parameters such as perfusion or metabolism must be assessed. The available modalities all have restricted clinical usefulness. The main aim of this thesis was to advance the clinical usefulness of perfusion and metabolism imaging in patients with neurodegenerative dementia, with a focus on visual assessment.A cohort of patients with neurodegenerative dementia was included, along with an age-matched control group. All subjects underwent MRI, including a pseudocontinuous ASL sequence and FDG-PET. In papers II and III, a subgroup containing both patients and controls underwent a second FDG-PET with reduced dose. In paper IV, the material was combined with a similar cohort from Amsterdam.Paper I showed that spatial smoothing increased the correlation between visually assessed perfusion and metabolism levels as displayed with FDG-PET. However, the distinction between patients and healthy controls was less satisfactory due to false positives.Paper II showed that differences in regional standard uptake value ratios between normal- and low-dose FDG-PET were small and without clinically significant bias.Paper III showed that the diagnostic performance of Z-score maps showing regions of significant deficits in metabolism was highly similar in normal- and low-dose FDG-PET images. Paper IV showed that ASL perfusion-based Z-score maps can be used for diagnostic purposes with high specificity, but inferior sensitivity, compared to FDG-PET.In conclusion, the included studies address aspects of the visual assessment of perfusion and metabolism neuroimaging, with a focus on clinical usefulness in diagnosing neurodegenerative dementia.
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| 3. |
- Law, Ian, et al.
(författare)
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Race and Racism in Eastern Europe : Becoming White, Becoming Western
- 2018
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Ingår i: Relating Worlds of Racism. - Cham : Palgrave Macmillan. - 9783319789897 - 9783319789903 ; , s. 113-139
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Bokkapitel (refereegranskat)abstract
- Law and Zakharov examine the formation and legacy of Russian racialisation and anti-Roma racism in a number of states including Hungary, the Czech Republic, Slovakia and Romania. They then examine racialisation in a variety of post-Soviet regimes including the Baltic states, Ukraine, Moldova, Belarus and the Southern Caucasus. The East European ‘search for race’ and the striving to ‘attain whiteness’, can be understood as attempts to rediscover the privileged whiteness that has been partly lost during the socialist past. Finally, they confirm the need to recognise polyracism, and give a less one-sided account of the process of racial Europeanisation which privileges Western Europe and denies the agency of Eastern European states in this process.
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| 4. |
- Lundemann, Michael, et al.
(författare)
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Feasibility of multi-parametric PET and MRI for prediction of tumour recurrence in patients with glioblastoma
- 2019
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 46:3, s. 603-613
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recurrence in glioblastoma patients often occur close to the original tumour and indicates that the current treatment is inadequate for local tumour control. In this study, we explored the feasibility of using multi-modality imaging at the time of radiotherapy planning. Specifically, we aimed to identify parameters from pre-treatment PET and MRI with potential to predict tumour recurrence. Materials and methods: Sixteen patients were prospectively recruited and treated according to established guidelines. Multi-parametric imaging with 18 F-FET PET/CT and 18 F-FDG PET/MR including diffusion and dynamic contrast enhanced perfusion MRI were performed before radiotherapy. Correlations between imaging parameters were calculated. Imaging was related to the voxel-wise outcome at the time of tumour recurrence. Within the radiotherapy target, median differences of imaging parameters in recurring and non-recurring voxels were calculated for contrast-enhancing lesion (CEL), non-enhancing lesion (NEL), and normal appearing grey and white matter. Logistic regression models were created to predict the patient-specific probability of recurrence. The most important parameters were identified using standardized model coefficients. Results: Significant median differences between recurring and non-recurring voxels were observed for FDG, FET, fractional anisotropy, mean diffusivity, mean transit time, extra-vascular, extra-cellular blood volume and permeability derived from scans prior to chemo-radiotherapy. Tissue-specific patterns of voxel-wise correlations were observed. The most pronounced correlations were observed for 18 F-FDG- and 18 F-FET-uptake in CEL and NEL. Voxel-wise modelling of recurrence probability resulted in area under the receiver operating characteristic curve of 0.77 from scans prior to therapy. Overall, FET proved to be the most important parameter for recurrence prediction. Conclusion: Multi-parametric imaging before radiotherapy is feasible and significant differences in imaging parameters between recurring and non-recurring voxels were observed. Combining parameters in a logistic regression model enabled patient-specific maps of recurrence probability, where 18 F-FET proved to be most important. This strategy could enable risk-adapted radiotherapy planning.
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| 5. |
- Munck af Rosenschöld, Per, et al.
(författare)
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Impact of [18F]-fluoro-ethyl-tyrosine PET imaging on target definition for radiation therapy of high-grade glioma.
- 2015
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Ingår i: Neuro-Oncology. - : Oxford University Press (OUP). - 1523-5866 .- 1522-8517. ; 17:5, s. 757-763
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Tidskriftsartikel (refereegranskat)abstract
- We sought to assess the impact of amino-acid (18)F-fluoro-ethyl-tyrosine (FET) positron emission tomography (PET) on the volumetric target definition for radiation therapy of high-grade glioma versus the current standard using MRI alone. Specifically, we investigated the influence of tumor grade, MR-defined tumor volume, and the extent of surgical resection on PET positivity.
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| 6. |
- Vandenberghe, Rik, et al.
(författare)
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F-18-Flutemetamol Amyloid Imaging in Alzheimer Disease and Mild Cognitive Impairment A Phase 2 Trial
- 2010
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Ingår i: Annals of Neurology. - : Wiley. - 1531-8249 .- 0364-5134. ; 68:3, s. 319-329
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The most widely studied positron emission tomography ligand for in vivo P-amyloid imaging is C-11-Pittsburgh compound B (C-11-PIB). Its availability, however, is limited by the need for an on-site cyclotron. Validation of the F-18-labeled PIB derivative F-18-flutemetamol could significantly enhance access to this novel technology. Methods: Twenty-seven patients with early-stage clinically probable Alzheimer disease (AD), 20 with amnestic mild cognitive impairment (MCI), and 15 cognitively intact healthy volunteers (HVs) above and 10 HVs below 55 years of age participated. The primary endpoint was the efficacy of blinded visual assessments of F-18-flutemetamol scans in assigning subjects to a raised versus normal uptake category, with clinical diagnosis as the standard of truth (SOT). As secondary objectives, we determined the correlation between the regional standardized uptake value ratios (SUVRs) for F-18-flutemetamol and its parent molecule C-11-PIB in 20 of the AD subjects and 20 of the MCI patients. We also determined test-retest variability of F-18-flutemetamol SUVRs in 5 of the AD subjects. Results: Blinded visual assessments of F-18-flutemetamol scans assigned 25 of 27 scans from AD subjects and 1 of 15 scans from the elderly HVs to the raised category, corresponding to a sensitivity of 93.1% and a specificity of 93.3% against the SOT. Correlation coefficients between cortical F-18-flutemetamol SUVRs and C-11-PIB SUVRs ranged from 0.89 to 0.92. Test-retest variabilities of regional SUVRs were 1 to 4%. Interpretation: F-18-Flutemetamol performs similarly to the C-11-PIB parent molecule within the same subjects and provides high test-retest replicability and potentially much wider accessibility for clinical and research use. ANN NEUROL 2010;68:319-329
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| 7. |
- Veit-Haibach, Patrick, et al.
(författare)
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International EANM-SNMMI-ISMRM consensus recommendation for PET/MRI in oncology
- 2023
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Nature. - 1619-7070 .- 1619-7089. ; 50:12, s. 3513-3537
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Tidskriftsartikel (refereegranskat)abstract
- The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and professional organization founded in 1954 to promote the science, technology, and practical application of nuclear medicine. The European Association of Nuclear Medicine (EANM) is a professional non-profit medical association that facilitates communication worldwide between individuals pursuing clinical and research excellence in nuclear medicine. The EANM was founded in 1985. The merged International Society for Magnetic Resonance in Medicine (ISMRM) is an international, nonprofit, scientific association whose purpose is to promote communication, research, development, and applications in the field of magnetic resonance in medicine and biology and other related topics and to develop and provide channels and facilities for continuing education in the field.The ISMRM was founded in 1994 through the merger of the Society of Magnetic Resonance in Medicine and the Society of Magnetic Resonance Imaging. SNMMI, ISMRM, and EANM members are physicians, technologists, and scientists specializing in the research and practice of nuclear medicine and/or magnetic resonance imaging.The SNMMI, ISMRM, and EANM will periodically define new guidelines for nuclear medicine practice to help advance the science of nuclear medicine and/or magnetic resonance imaging and to improve the quality of service to patients throughout the world. Existing practice guidelines will be reviewed for revision or renewal, as appropriate, on their fifth anniversary or sooner, if indicated. Each practice guideline, representing a policy statement by the SNMMI/EANM/ISMRM, has undergone a thorough consensus process in which it has been subjected to extensive review. The SNMMI, ISMRM, and EANM recognize that the safe and effective use of diagnostic nuclear medicine imaging and magnetic resonance imaging requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guideline by those entities not providing these services is not authorized.These guidelines are an educational tool designed to assist practitioners in providing appropriate care for patients. They are not inflexible rules or requirements of practice and are not intended, nor should they be used, to establish a legal standard of care. For these reasons and those set forth below, the SNMMI, the ISMRM, and the EANM caution against the use of these guidelines in litigation in which the clinical decisions of a practitioner are called into question.The ultimate judgment regarding the propriety of any specific procedure or course of action must be made by the physician or medical physicist in light of all the circumstances presented. Thus, there is no implication that an approach differing from the guidelines, standing alone, is below the standard of care. To the contrary, a conscientious practitioner may responsibly adopt a course of action different from that set forth in the guidelines when, in the reasonable judgment of the practitioner, such course of action is indicated by the condition of the patient, limitations of available resources, or advances in knowledge or technology subsequent to publication of the guidelines.The practice of medicine includes both the art and the science of the prevention, diagnosis, alleviation, and treatment of disease. The variety and complexity of human conditions make it impossible to always reach the most appropriate diagnosis or to predict with certainty a particular response to treatment.Therefore, it should be recognized that adherence to these guidelines will not ensure an accurate diagnosis or a successful outcome. All that should be expected is that the practitioner will follow a reasonable course of action based on current knowledge, available resources, and the needs of the patient to deliver effective and safe medical care. The sole purpose of these guidelines is to assist practitioners in achieving this objective.
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| 8. |
- Zakharov, Nikolay, 1978-
(författare)
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Attaining Whiteness : A Sociological Study of Race and Racialization in Russia
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Attaining Whiteness is the first book-length sociological study of how ideas about race resonate in post-Soviet Russia. The book charts how tropes of self, hybridity, and maturity constitute important symbolic vehicles for applying the idea of race to the drawing of differences. A new theoretical framework is developed that casts light on fields of study that have not yet received sufficient attention in Western European and American research concerning racial issues. This study of racialization takes a step towards providing a better understanding of how the discourses of race are extended and transformed through the production of social knowledge and social relations. This volume addresses the resilience of genetic criteria for defining cultures and behaviors in both the sciences and humanities in Russia, and also examines the ongoing and pervasive policy of racialized exclusion. The study argues that the concepts and practices of race, whiteness, and Russianness operate ambivalently insofar as they both hold the social fabric together, organizing the perception of the “Other”, but also undermine the unity of society. Racialization thus fosters, first, the sense that Russia belongs to the core of civilization as opposed to the Third World; second, the formulation of policies towards the internal peripheries that support social control informed by the notion of human material; and, finally, the promotion of exclusionary ethnic self-identifications that employ the discourse of hybridity.
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| 9. |
- Zakharov, Nikolay, et al.
(författare)
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Central Asian Racisms
- 2017
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Ingår i: Post-Soviet Racisms. - London : Palgrave Macmillan. - 9781137476913 - 9781137476920 ; , s. 129-183
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter emphasizes the contradictory composition of the discourses of race in Central Asia―whereby it can be conceptualized both as breed (or lineage), which is supported by the discourses of nationalism and clan politics, and as type (or phenotype), which is supported by folk conceptions borrowed from the Soviet and post-Soviet experiences of racialization. The fluid character of racism in the region obstructs any non-contradictory formation of the racial order. The logic of racialization demands both internal and external “others”, which leads to contradictions within the available intellectual programs of nation-building under the conditions of striving to legitimize inequality and authoritarian rule. It is self-contradictory in its two functions of responding to the traumatic challenges of the neighboring countries and Russia and of naturalizing social differences at home. The weakness of civil society and of institutions endeavoring to apply transparency and meritocracy as their operating principles has resulted in a situation in which Central Asian states have not succeeded in questioning the institutionalized ascription of a variety of social markers, such as racialized ethnic belonging.
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| 10. |
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