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- Alvén, Jennifer, 1989, et al.
(författare)
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A Deep Learning Approach to MR-less Spatial Normalization for Tau PET Images
- 2019
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Ingår i: Medical Image Computing and Computer Assisted Intervention : MICCAI 2019 - 22nd International Conference, Proceedings - MICCAI 2019 - 22nd International Conference, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783030322441 - 9783030322458 ; 11765 LNCS, s. 355-363
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Konferensbidrag (refereegranskat)abstract
- The procedure of aligning a positron emission tomography (PET) image with a common coordinate system, spatial normalization, typically demands a corresponding structural magnetic resonance (MR) image. However, MR imaging is not always available or feasible for the subject, which calls for enabling spatial normalization without MR, MR-less spatial normalization. In this work, we propose a template-free approach to MR-less spatial normalization for [18F]flortaucipir tau PET images. We use a deep neural network that estimates an aligning transformation from the PET input image, and outputs the spatially normalized image as well as the parameterized transformation. In order to do so, the proposed network iteratively estimates a set of rigid and affine transformations by means of convolutional neural network regressors as well as spatial transformer layers. The network is trained and validated on 199 tau PET volumes with corresponding ground truth transformations, and tested on two different datasets. The proposed method shows competitive performance in terms of registration accuracy as well as speed, and compares favourably to previously published results.
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| 2. |
- Andersson, Carl-Henrik, et al.
(författare)
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A Genetic Variant of the Sortilin 1 Gene is Associated with Reduced Risk of Alzheimer's Disease
- 2016
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 53:4, s. 1353-1363
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is a neurodegenerative disorder represented by the accumulation of intracellular tau protein and extracellular deposits of amyloid-β (Aβ) in the brain. The gene sortilin 1 (SORT1) has previously been associated with cardiovascular disease in gene association studies. It has also been proposed to be involved in AD pathogenesis through facilitating Aβ clearance by binding apoE/Aβ complexes prior to cellular uptake. However, the neuropathological role of SORT1 in AD is not fully understood. To evaluate the associations between gene variants of SORT1 and risk of AD, we performed genetic analyses in a Swedish case-control cohort. Ten single nucleotide polymorphisms (SNPs), covering the whole SORT1 gene, were selected and genotyped in 620 AD patients and 1107 controls. The SNP rs17646665, located in a non-coding region of the SORT1 gene, remained significantly associated with decreased risk of AD after multiple testing (pc = 0.0061). In addition, other SNPs were found to be nominally associated with risk of AD, as well as altered cognitive function and the CSF biomarker Aβ42, but these associations did not survive correction for multiple testing. The fact that SORT1 has been strongly associated with risk of cardiovascular disease is intriguing as cardiovascular disease is also regarded as a risk factor for AD. Finally, increased knowledge about SORT1 function has a potential to increase our understanding of APOE, the strongest risk factor for AD.
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| 4. |
- Hansson, Julia, et al.
(författare)
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How is biodiversity protection influencing the potential for bioenergy feedstock production on grasslands?
- 2018
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Ingår i: Global Change Biology Bioenergy. - : Wiley. - 1757-1693 .- 1757-1707. ; 11:3, s. 515-538
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable feedstock supply is a critical issue for the bioenergy sector. The sustainability criteria for biofuels in the EU Renewable Energy Directive (RED) prohibit the use of raw material from land with high biodiversity, i.e., areas designated for nature protection purposes, primary forest and highly biodiverse grassland. This paper addresses how biodiversity considerations influence the prospects for biomass production for bioenergy on grasslands. No globally established approach exists to assess and quantify grassland availability for bioenergy while considering biodiversity. We investigate how biodiverse grasslands are considered in (i) assessments of bioenergy supply potentials; (ii) the RED, the EU Common Agricultural Policy (CAP), and the UN Convention on Biological Diversity (CBD); and (iii) land-use governance and nature protection in Brazil. Estimates of biomass supply potentials commonly treat biodiverse grasslands as unavailable for bioenergy, when considering broader nature protection requirements. Few studies allow for a direct quantification of how biodiversity considerations relating to grasslands influence the global biomass supply potential. The definitions of natural and non-natural grassland in the RED are similar to those in the CAP. The RED complements and strengthens the protective ambitions in the CAP and CBD, but a lack of clear definitions and guidance in relation to the RED creates uncertainty about the prospects for biofuels from grasslands on the EU market. For EU-28, an estimated 39-48% (about 9-11 Mha) and 15-54% (about 10-38 Mha) of natural and non-natural grassland, respectively, may be considered highly biodiverse. In Brazil, economic-ecological zoning can be important for grassland conservation since almost half of the native grassland on private land is unprotected and subject to farmers’ preferences, which may favor protecting forest over grassland. Further clarification of grassland definitions and delineation in regulations will significantly influence the prospects for bioenergy from grasslands, and the impacts of bioenergy deployment on biodiversity.
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