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- Yaroshenko, A., et al.
(författare)
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Preclinical x-ray dark-field radiography for pulmonary emphysema evaluation
- 2013
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Ingår i: ISBI 2013 - 2013 IEEE 10th International Symposium on Biomedical Imaging : From Nano to Macro - From Nano to Macro. - 1945-7928 .- 1945-8452. - 9781467364553 - 9781467364560 ; , s. 370-373
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Konferensbidrag (refereegranskat)abstract
- Pulmonary emphysema is a widespread disorder characterized by irreversible destruction of alveolar walls. The spatial distribution of the disease, so far, could only be obtained using an x-ray CT scan, implying a high patient dose. X-ray scattering on alveolar structures is measured in the dark-field signal. The signal is dependent on the size of alveoli and therefore, a combination of absorption and dark-field signal is explored for mapping the distribution of emphysema in the lung on x-ray projection images. In this study three excised murine lungs with pulmonary emphysema and three control samples were imaged using a compact, cone-beam, small-animal x-ray dark-field scanner with a polychromatic source. Statistical analysis of the results, based on a combination of transmission and dark-field signals, revealed a distinct difference between emphysematous and control samples. Subsequently, the distribution of emphysema was mapped out per-pixel for the lungs and showed good agreement with histological findings.
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| 4. |
- Hansmann, G., et al.
(författare)
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Selexipag for the treatment of children with pulmonary arterial hypertension: First multicenter experience in drug safety and efficacy
- 2020
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Ingår i: Journal of Heart and Lung Transplantation. - : Elsevier BV. - 1053-2498. ; 39:7, s. 695-706
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The European Pediatric Pulmonary Vascular Disease Network (EPPVDN) investigated the safety and efficacy of add-on selexipag, an oral prostacyclin receptor agonist approved for pulmonary arterial hypertension (PAH) in adults, in the largest, exploratory pediatric cohort to date. METHODS: This is a prospective observational study of 15 consecutive children with PAH, treated with oral add-on selexipag at 3 centers. Most patients underwent cardiac catheterizations at baseline and median of 8 months follow-up. All patients had clinical, echocardiographic, and N-terminal pro b-type natriuretic peptide studies, including the EPPVDN pediatric pulmonary hypertension (PH) risk score. RESULTS: There was no death during the use of selexipag. Two of 15 patients ultimately underwent lung transplantation. One patient with heritable PAH died on intravenous treprostinil (off selexipag). The mean right atrial pressure, the ratio of pulmonary arterial pressure (PAP) to systemic arterial pressure (SAP) (mean PAP/mean SAP, diastolic PAP/diastolic SAP: -17%), and transpulmonary pressure gradients (TPG) (mean TPG: -17%; p < 0.01; diastolic TPG: -6 mm Hg; p < 0.05) were improved after the therapy (n = 10). Selexipag therapy was associated with a better right ventricular systolic function (tricuspid annular plane systolic excursion: +14.5%; p < 0.01) and functional class. Improvement was seen in non-invasive and combined invasive/non-invasive PH risk scores (lower risk: +18%-22%, higher risk: -35%-37%; p < 0.05). Overall, the efficacy of selexipag was variable, often with a better response in less sick patients. CONCLUSIONS: Oral selexipag use in children with PAH is well tolerated and safe when closely monitored. Add-on selexipag therapy improved several outcome-relevant variables in about 50% of patients and prevented disease progression in additional 27% of patients. The novel EPPVDN pediatric PH risk score indicated these drug effects properly, can be useful in clinical follow-up, and should be validated in larger prospective studies. (C) 2020 The Author(s). Published by Elsevier Inc. on behalf of International Society for Heart and Lung Transplantation. This is an open access article under the CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/)
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- Khrapov, D., et al.
(författare)
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Different approaches for manufacturing ti-6al-4v alloy with triply periodic minimal surface sheet-based structures by electron beam melting
- 2021
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:17
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Tidskriftsartikel (refereegranskat)abstract
- Targeting biomedical applications, Triply Periodic Minimal Surface (TPMS) gyroid sheet-based structures were successfully manufactured for the first time by Electron Beam Melting in two different production Themes, i.e., inputting a zero (Wafer Theme) and a 200 µm (Melt Theme) wall thickness. Initial assumption was that in both cases, EBM manufacturing should yield the structures with similar mechanical properties as in a Wafer-mode, as wall thickness is determined by the minimal beam spot size of ca 200 µm. Their surface morphology, geometry, and mechanical properties were investigated by means of electron microscopy (SEM), X-ray Computed Tomography (XCT), and uniaxial tests (both compression and tension). Application of different manufacturing Themes resulted in specimens with different wall thicknesses while quasi-elastic gradients for different Themes was found to be of 1.5 GPa, similar to the elastic modulus of human cortical bone tissue. The specific energy absorption at 50% strain was also similar for the two types of structures. Finite element simulations were also conducted to qualitatively analyze the deformation process and the stress distribution under mechanical load. Simulations demonstrated that in the elastic regime wall, regions oriented parallel to the load are primarily affected by deformation. We could conclude that gyroids manufactured in Wafer and Melt Themes are equally effective in mimicking mechanical properties of the bones.
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- Khrapov, D., et al.
(författare)
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Geometrical features and mechanical properties of the sheet-based gyroid scaffolds with functionally graded porosity manufactured by electron beam melting
- 2023
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Ingår i: Materials Today Communications. - : Elsevier. - 2352-4928. ; 35
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Tidskriftsartikel (refereegranskat)abstract
- Functionally graded porous scaffolds (FGPS) constructed with pores of different size arranged as spatially continuous structure based on sheet-based gyroid with three different scaling factors of 0.05, 0.1 and 0.2 were produced by electron beam powder bed fusion. The pore dimensions of the obtained scaffolds satisfy the values required for optimal bone tissue ingrowth. Agglomerates of residual powder were found inside all structures, which required post-manufacturing treatment. Using X-ray Computed Tomography powder agglomerations were visualized and average wall thickness, wall-to-wall distances, micro- and macro-porosities were evaluated. The initial cleaning by powder recovery system (PRS) was insufficient for complete powder removal. Additional treatment by dry ultrasonic vibration (USV) was applied and was found successful for gyroids with the scaling factors of 0.05 and 0.1. Mechanical properties of the samples, including quasi-elastic gradients and first maximum compressive strengths of the structures before and after USV were evaluated to prove that additional treatment does not produce structural damage. The estimated quasi-elastic gradients for gyroids with different scaling factors lie in a range between 2.5 and 2.9 GPa, while the first maximum compressive strength vary from 52.5 for to 59.8 MPa, compressive offset stress vary from 46.2 for to 53.2 MPa.
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| 7. |
- Velroyen, A, et al.
(författare)
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Grating-based X-ray Dark-field Computed Tomography of Living Mice.
- 2015
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Ingår i: EBioMedicine. - : Elsevier BV. - 2352-3964. ; 2:10, s. 1500-1506
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Tidskriftsartikel (refereegranskat)abstract
- Changes in x-ray attenuating tissue caused by lung disorders like emphysema or fibrosis are subtle and thus only resolved by high-resolution computed tomography (CT). The structural reorganization, however, is of strong influence for lung function. Dark-field CT (DFCT), based on small-angle scattering of x-rays, reveals such structural changes even at resolutions coarser than the pulmonary network and thus provides access to their anatomical distribution. In this proof-of-concept study we present x-ray in vivo DFCTs of lungs of a healthy, an emphysematous and a fibrotic mouse. The tomographies show excellent depiction of the distribution of structural - and thus indirectly functional - changes in lung parenchyma, on single-modality slices in dark field as well as on multimodal fusion images. Therefore, we anticipate numerous applications of DFCT in diagnostic lung imaging. We introduce a scatter-based Hounsfield Unit (sHU) scale to facilitate comparability of scans. In this newly defined sHU scale, the pathophysiological changes by emphysema and fibrosis cause a shift towards lower numbers, compared to healthy lung tissue.
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| 9. |
- Hellbach, Katharina, et al.
(författare)
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In Vivo Dark-Field Radiography for Early Diagnosis and Staging of Pulmonary Emphysema.
- 2015
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Ingår i: Investigative Radiology. - 0020-9996. ; 50:7, s. 430-435
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the suitability of in vivo x-ray dark-field radiography for early-stage diagnosis of pulmonary emphysema in mice. Furthermore, we aimed to analyze how the dark-field signal correlates with morphological changes of lung architecture at distinct stages of emphysema.
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| 11. |
- Yaroshenko, Andre, et al.
(författare)
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Improved In vivo Assessment of Pulmonary Fibrosis in Mice using X-Ray Dark-Field Radiography.
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease with a median life expectancy of 4-5 years after initial diagnosis. Early diagnosis and accurate monitoring of IPF are limited by a lack of sensitive imaging techniques that are able to visualize early fibrotic changes at the epithelial-mesenchymal interface. Here, we report a new x-ray imaging approach that directly visualizes the air-tissue interfaces in mice in vivo. This imaging method is based on the detection of small-angle x-ray scattering that occurs at the air-tissue interfaces in the lung. Small-angle scattering is detected with a Talbot-Lau interferometer, which provides the so-called x-ray dark-field signal. Using this imaging modality, we demonstrate-for the first time-the quantification of early pathogenic changes and their correlation with histological changes, as assessed by stereological morphometry. The presented radiography method is significantly more sensitive in detecting morphological changes compared with conventional x-ray imaging, and exhibits a significantly lower radiation dose than conventional x-ray CT. As a result of the improved imaging sensitivity, this new imaging modality could be used in future to reduce the number of animals required for pulmonary research studies.
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