Alves, Frauke

[["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.issue","02"],["dc.bibliographiccitation.journal","Journal of Medical Imaging"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Reichardt, Marius"],["dc.contributor.author","Töpperwien, Mareike"],["dc.contributor.author","Khan, Amara"],["dc.contributor.author","Alves, Frauke"],["dc.contributor.author","Salditt, Tim"],["dc.date.accessioned","2020-03-10T15:14:49Z"],["dc.date.available","2020-03-10T15:14:49Z"],["dc.date.issued","2020"],["dc.description.abstract","Purpose: We present a phase-contrast x-ray tomography study of wild type C57BL/6 mouse hearts as a nondestructive approach to the microanatomy on the scale of the entire excised organ. Based on the partial coherence at a home-built phase-contrast μ-CT setup installed at a liquid metal jet source, we exploit phase retrieval and hence achieve superior image quality for heart tissue, almost comparable to previous synchrotron data on the whole organ scale. Approach: In our work, different embedding methods and heavy metal-based stains have been explored. From the tomographic reconstructions, quantitative structural parameters describing the three-dimensional (3-D) architecture have been derived by two different fiber tracking algorithms. The first algorithm is based on the local gradient of the reconstructed electron density. By performing a principal component analysis on the local structure-tensor of small subvolumes, the dominant direction inside the volume can be determined. In addition to this approach, which is already well established for heart tissue, we have implemented and tested an algorithm that is based on a local 3-D Fourier transform. Results: We showed that the choice of sample preparation influences the 3-D structure of the tissue, not only in terms of contrast but also with respect to the structural preservation. A heart prepared with the evaporation-of-solvent method was used to compare both algorithms. The results of structural orientation were very similar for both approaches. In addition to the determination of the fiber orientation, the degree of filament alignment and local thickness of single muscle fiber bundles were obtained using the Fourier-based approach. Conclusions: Phase-contrast x-ray tomography allows for investigating the structure of heart tissue with an isotropic resolution below 10  μm. The fact that this is possible with compact laboratory instrumentation opens up new opportunities for screening samples and optimizing sample preparation, also prior to synchrotron beamtimes. Further, results from the structural analysis can help in understanding cardiovascular diseases or can be used to improve computational models of the heart."],["dc.identifier.doi","10.1117/1.JMI.7.2.023501"],["dc.identifier.pmid","32206684"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/63285"],["dc.identifier.url","https://mbexc.uni-goettingen.de/literature/publications/194"],["dc.language.iso","en"],["dc.relation","EXC 2067: Multiscale Bioimaging"],["dc.relation.issn","2329-4302"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.relation.workinggroup","RG Alves (Translationale Molekulare Bildgebung)"],["dc.subject.gro","biomedical tomography"],["dc.title","Fiber orientation in a whole mouse heart reconstructed by laboratory phase-contrast micro-CT"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","4"],["dc.contributor.author","Nicolas, J. D."],["dc.contributor.author","Markus, Marietta Andrea"],["dc.contributor.author","Alves, Frauke"],["dc.contributor.author","Frohn, Jasper"],["dc.contributor.author","Reichardt, Marius"],["dc.contributor.author","Töpperwien, Mareike"],["dc.contributor.author","Salditt, Tim"],["dc.contributor.editor","Wang, Geng"],["dc.contributor.editor","Müller-Myhsok, Bertram"],["dc.date.accessioned","2020-06-26T10:11:47Z"],["dc.date.available","2020-06-26T10:11:47Z"],["dc.date.issued","2017"],["dc.description.abstract","In this work we present x-ray phase-contrast tomography of heart tissue from mouse, combining computed tomography (CT) scans with laboratory and synchrotron radiation. The work serves as a proof-of-concept that the cyto-architecture and in particular the myofibril orientation can be assessed in three dimensions (3D) by phase-contrast CT. We demonstrate the synergistic use of laboratory μ -CT and of the high resolution synchrotron setup based on waveguide optics. Details on preparation, instrumentation and analysis are given, as a state of the art reference for heart tissue tomography, and as a starting point for further progress."],["dc.identifier.doi","10.1117/12.2276648"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/66750"],["dc.language.iso","en"],["dc.notes.preprint","yes"],["dc.relation.eventend","2017-09-25"],["dc.relation.eventlocation","San Diego"],["dc.relation.eventstart","2017-09-25"],["dc.relation.isbn","9781510612396"],["dc.relation.isbn","9781510612402"],["dc.relation.iserratumof","yes"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.subject.gro","x-ray optics"],["dc.subject.gro","x-ray imaging"],["dc.subject.gro","biomedical tomography"],["dc.title","Nanoscale holographic tomography of heart tissue with x-ray waveguide optics"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","282"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Acta Crystallographica Section A Foundations and Advances"],["dc.bibliographiccitation.lastpage","292"],["dc.bibliographiccitation.volume","73"],["dc.contributor.author","Krenkel, Martin"],["dc.contributor.author","Toepperwien, Mareike"],["dc.contributor.author","Alves, Frauke"],["dc.contributor.author","Salditt, Tim"],["dc.date.accessioned","2022-03-01T11:47:06Z"],["dc.date.available","2022-03-01T11:47:06Z"],["dc.date.issued","2017"],["dc.description.abstract","X-ray tomography at the level of single biological cells is possible in a low-dose regime, based on full-field holographic recordings, with phase contrast originating from free-space wave propagation. Building upon recent progress in cellular imaging based on the illumination by quasi-point sources provided by X-ray waveguides, here this approach is extended in several ways. First, the phase-retrieval algorithms are extended by an optimized deterministic inversion, based on a multi-distance recording. Second, different advanced forms of iterative phase retrieval are used, operational for single-distance and multi-distance recordings. Results are compared for several different preparations of macrophage cells, for different staining and labelling. As a result, it is shown that phase retrieval is no longer a bottleneck for holographic imaging of cells, and how advanced schemes can be implemented to cope also with high noise and inconsistencies in the data."],["dc.description.abstract","X-ray tomography at the level of single biological cells is possible in a low-dose regime, based on full-field holographic recordings, with phase contrast originating from free-space wave propagation. Building upon recent progress in cellular imaging based on the illumination by quasi-point sources provided by X-ray waveguides, here this approach is extended in several ways. First, the phase-retrieval algorithms are extended by an optimized deterministic inversion, based on a multi-distance recording. Second, different advanced forms of iterative phase retrieval are used, operational for single-distance and multi-distance recordings. Results are compared for several different preparations of macrophage cells, for different staining and labelling. As a result, it is shown that phase retrieval is no longer a bottleneck for holographic imaging of cells, and how advanced schemes can be implemented to cope also with high noise and inconsistencies in the data."],["dc.identifier.doi","10.1107/S2053273317007902"],["dc.identifier.doi","10.1107/s2053273317007902"],["dc.identifier.gro","3142469"],["dc.identifier.pii","S2053273317007902"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/103911"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-531"],["dc.notes.status","final"],["dc.relation.eissn","2053-2733"],["dc.relation.issn","2053-2733"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.relation.workinggroup","RG Salditt (Structure of Biomolecular Assemblies and X-Ray Physics)"],["dc.rights.uri","http://creativecommons.org/licenses/by/2.0/uk/legalcode"],["dc.subject.gro","x-ray imaging"],["dc.subject.gro","biomedical tomography"],["dc.title","Three-dimensional single-cell imaging with X-ray waveguides in the holographic regime"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]