| 11. |
- Cibis, Merih, et al.
(author)
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Creating Hemodynamic Atlases of Cardiac 4D Flow MRI
- 2017
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In: Journal of Magnetic Resonance Imaging. - : WILEY. - 1053-1807 .- 1522-2586. ; 46:5, s. 1389-1399
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Journal article (peer-reviewed)abstract
- Purpose: Hemodynamic atlases can add to the pathophysiological understanding of cardiac diseases. This study proposes a method to create hemodynamic atlases using 4D Flow magnetic resonance imaging (MRI). The method is demonstrated for kinetic energy (KE) and helicity density (Hd). Materials and Methods: Thirteen healthy subjects underwent 4D Flow MRI at 3T. Phase-contrast magnetic resonance cardioangiographies (PC-MRCAs) and an average heart were created and segmented. The PC-MRCAs, KE, and Hd were nonrigidly registered to the average heart to create atlases. The method was compared with 1) rigid, 2) affine registration of the PC-MRCAs, and 3) affine registration of segmentations. The peak and mean KE and Hd before and after registration were calculated to evaluate interpolation error due to nonrigid registration. Results: The segmentations deformed using nonrigid registration overlapped (median: 92.3%) more than rigid (23.1%, P amp;lt; 0.001), and affine registration of PC-MRCAs (38.5%, P amp;lt; 0.001) and affine registration of segmentations (61.5%, P amp;lt; 0.001). The peak KE was 4.9 mJ using the proposed method and affine registration of segmentations (P50.91), 3.5 mJ using rigid registration (P amp;lt; 0.001), and 4.2 mJ using affine registration of the PC-MRCAs (P amp;lt; 0.001). The mean KE was 1.1 mJ using the proposed method, 0.8 mJ using rigid registration (P amp;lt; 0.001), 0.9 mJ using affine registration of the PC-MRCAs (P amp;lt; 0.001), and 1.0 mJ using affine registration of segmentations (P50.028). The interpolation error was 5.262.6% at mid-systole, 2.863.8% at early diastole for peak KE; 9.669.3% at mid-systole, 4.064.6% at early diastole, and 4.964.6% at late diastole for peak Hd. The mean KE and Hd were not affected by interpolation. Conclusion: Hemodynamic atlases can be obtained with minimal user interaction using nonrigid registration of 4D Flow MRI. Level of Evidence: 2 Technical Efficacy: Stage 1
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| 12. |
- Danielson, Mattias, et al.
(author)
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Neuroinflammatory markers associate with cognitive decline after major surgery: Findings of an explorative study
- 2020
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In: Annals of Neurology. - : Wiley. - 0364-5134 .- 1531-8249. ; 87:3, s. 370-382
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Journal article (peer-reviewed)abstract
- Objective Long-term cognitive decline is an adverse outcome after major surgery associated with increased risk for mortality and morbidity. We studied the cerebrospinal fluid (CSF) and serum biochemical inflammatory response to a standardized orthopedic surgical procedure and the possible association with long-term changes in cognitive function. We hypothesized that the CSF inflammatory response pattern after surgery would differ in patients having long-term cognitive decline defined as a composite cognitive z score of >= 1.0 compared to patients without long-term cognitive decline at 3 months postsurgery. Methods Serum and CSF biomarkers of inflammation and blood-brain barrier (BBB) integrity were measured preoperatively and up to 48 hours postoperatively, and cognitive function was assessed preoperatively and at 2 to 5 days and 3 months postoperatively. Results Surgery was associated with a pronounced increase in inflammatory biomarkers in both CSF and blood throughout the 48-hour study period. A principal component (PC) analysis was performed on 52 inflammatory biomarkers. The 2 first PC (PC1 and PC2) construct outcome variables on CSF biomarkers were significantly associated with long-term cognitive decline at 3 months, but none of the PC construct serum variables showed a significant association with long-term cognitive decline at 3 months. Patients both with and patients without long-term cognitive decline showed early transient increases of the astroglial biomarkers S-100B and glial fibrillary acidic protein in CSF, and in BBB permeability (CSF/serum albumin ratio). Interpretation Surgery rapidly triggers a temporal neuroinflammatory response closely associated with long-term cognitive outcome postsurgery. The findings of this explorative study require validation in a larger surgical patient cohort.
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| 13. |
- Danielsson, Mattias, et al.
(author)
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Association between cerebrospinal fluid biomarkers of neuronal injury or amyloidosis and cognitive decline after major surgery.
- 2021
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In: British journal of anaesthesia. - : Elsevier BV. - 1471-6771 .- 0007-0912. ; 126:2, s. 467-76
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Journal article (peer-reviewed)abstract
- Postoperative neurocognitive decline is a frequent complication in adult patients undergoing major surgery with increased risk for morbidity and mortality. The mechanisms behind cognitive decline after anaesthesia and surgery are not known. We studied the association between CSF and blood biomarkers of neuronal injury or brain amyloidosis and long-term changes in neurocognitive function.In patients undergoing major orthopaedic surgery (knee or hip replacement), blood and CSF samples were obtained before surgery and then at 4, 8, 24, 32, and 48 h after skin incision through an indwelling spinal catheter. CSF and blood concentrations of total tau (T-tau), neurofilament light, neurone-specific enolase and amyloid β (Aβ1-42) were measured. Neurocognitive function was assessed using the International Study of Postoperative Cognitive Dysfunction (ISPOCD) test battery 1-2 weeks before surgery, at discharge from the hospital (2-5 days after surgery), and at 3 months after surgery.CSF and blood concentrations of T-tau, neurone-specific enolase, and Aβ1-42 increased after surgery. A similar increase in serum neurofilament light was seen with no overall changes in CSF concentrations. There were no differences between patients having a poor or good late postoperative neurocognitive outcome with respect to these biomarkers of neuronal injury and Aβ1-42.The findings of the present explorative study showed that major orthopaedic surgery causes a release of CSF markers of neural injury and brain amyloidosis, suggesting neuronal damage or stress. We were unable to detect an association between the magnitude of biomarker changes and long-term postoperative neurocognitive dysfunction.
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| 14. |
- Dyverfeldt, Petter, et al.
(author)
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Extending 4D Flow Visualization to the Human Right Ventricle
- 2009
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In: Proceedings of International Society for Magnetic Resonance in Medicine: 17th Scientific Meeting 2009. - : International Society for Magnetic Resonance in Medicine. ; , s. 3860-3860
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Conference paper (peer-reviewed)abstract
- The right ventricle has an important role in cardiovascular disease. However, because of the complex geometry and the sensitivity to the respiratory cycle, imaging of the right ventricle is challenging. We investigated whether 3D cine phase-contrast MRI can provide data with sufficient accuracy for visualizations of the 4D blood flow in the right ventricle. Whole-heart 4D flow measurements with optimized imaging parameters and post-processing tools were made in healthy volunteers. Pathlines emitted from the right atrium could be traced through the right ventricle to the pulmonary artery without leaving the blood pool and thereby met our criteria for sufficient accuracy.
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| 15. |
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| 16. |
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| 17. |
- Eriksson, Alexander, et al.
(author)
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Virtual factory layouts from 3D laser scanning – A novel framework to define solid model requirements
- 2018
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 76, s. 36-41
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Conference paper (peer-reviewed)abstract
- In a world with increasing customer demands, manufacturing companies must develop and produce products more rapidly and adapt their production systems offline, to not disturb the ongoing processes. This creates a demand of using digital production development so that development can be performed in parallel with production. Virtual factory layouts (VFLs) are essential for companies in order to plan their factory layout and evaluate production scenarios. However, requirements for a VFL depends heavily on its purpose. For example, the requirements on a model for offline programming of robots are different from those on a model used to determine buffer locations. There is currently a lack of clear guidelines for how developed a VFL should be to fulfil said requirements, which contributes to unnecessary modelling time and variation in delivery quality. This paper aims to put the actual demands and requirements of a VFL in focus. By adapting a Level of Development-framework for establishment of Building Information Models (BIMs) and connecting it to the purpose of VFLs, development of a framework for detail and functionality level of VFLs is enabled. Such a purpose-oriented framework will help to define delivery packages suited for different circumstances, which will provide the modeler with knowledge of how much detail and functionality a specific model should contain. The increased clarity provided by the developed framework results in a clearer connection between expected result and actual output from a custom VFL project. Also, by connecting model properties or development to the model-purpose, the framework brings clarity and structure to a currently vague field. This provides means for a more efficient and accurate use of VFLs, which will support the rapid development of production facilities.
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| 18. |
- Eriksson, Gustav, et al.
(author)
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Boundary and interface methods for energy stable finite difference discretizations of the dynamic beam equation
- 2023
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In: Journal of Computational Physics. - : Elsevier. - 0021-9991 .- 1090-2716. ; 476
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Journal article (peer-reviewed)abstract
- We consider energy stable summation by parts finite difference methods (SBP-FD) for the homogeneous and piecewise homogeneous dynamic beam equation (DBE). Previously the constant coefficient problem has been solved with SBP-FD together with penalty terms (SBP-SAT) to impose boundary conditions. In this work, we revisit this problem and compare SBP-SAT to the projection method (SBP-P). We also consider the DBE with discontinuous coefficients and present novel SBP-SAT, SBP-P, and hybrid SBP-SAT-P discretizations for imposing interface conditions. To demonstrate the methodology for two-dimensional problems, we also present a discretization of the piecewise homogeneous dynamic Kirchoff-Love plate equation based on the hybrid SBP-SAT-P method. Numerical experiments show that all methods considered are similar in terms of accuracy, but that SBP-P can be more computationally efficient (less restrictive time step requirement for explicit time integration methods) for both the constant and piecewise constant coefficient problems.
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| 19. |
- Eriksson, Jonatan
(author)
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Algorithms and Methods for Robust Processing and Analysis of Mass Spectrometry Data
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Liquid chromatography-mass spectrometry (LC-MS) and mass spectrometry imaging (MSI) are two techniques that are routinely used to study proteins, peptides, and metabolites at a large scale. Thousands of biological compounds can be identified and quantified in a single experiment with LC-MS, but many studies fail to convert this data to a better understanding of disease biology. One of the primary reasons for this is low reproducibility, which in turn is partially due to inaccurate and/or inconsistent data processing. Protein biomarkers and signatures for various types of cancer are frequently discovered with LC-MS, but their behavior in independent cohorts is often inconsistent to that in the discovery cohort. Biomarker candidates must be thoroughly validated in independent cohorts, which makes the ability to share data across different laboratories crucial to the future success of the MS-based research fields. The emergence and growth of public repositories for MSI data is a step in the rightdirection. Still, many of those data sets remain incompatible one another due to inaccurate or incompatible preprocessing strategies. Ensuring compatibility between data generated in different labs is therefore necessary to gain access to the full potential of MS-based research. In two of the studies that I present in this thesis, we used LC-MS to characterize lymph node metastases from individuals with melanoma. Furthermore, my thesis work has resulted in two novel preprocessing methods for MSI data sets. The first one is a peak detection method that achieves considerably higher sensitivity for faintly expressed compounds than existing methods, and the second one is a accurate, robust, and general approach to mass alignment. Both algorithms deliberately rely on centroid spectra, which makes them compatible with most shared data sets. I believe that the improvements demonstrated by these methods can lead to a higher reproducibility in the MS-based research fields, and, ultimately, to a better understanding of disease processes.
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| 20. |
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