Neodymium acetate as a contrast agent for x-ray phase-contrast tomography

Reichmann, Jakob; Ruhwedel, Torben; Möbius, Wiebke; Salditt, Tim

doi:10.1117/12.2627682

Cited by 3 publications

(4 citation statements)

References 41 publications

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“…can provide ground truth for such algorithm development. While providing good contrast, heavy-metal stains might in fact not be ideal for X-ray imaging and materials with similar dissipation butsignificantly reduced absorption (Busse et al, 2021;Reichmann et al, 2023) might further improve sample stability.…”

Section: Discussionmentioning

confidence: 99%

Non-destructive X-ray tomography of brain tissue ultrastructure

Bosch,

Aidukas,

Holler

et al. 2023

Preprint

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Wiring diagrams of neural circuits are of central importance in delineating mechanisms of computation in the brain (Lichtman and Sanes, 2008; Litwin-Kumar and Turaga, 2019). To generate these diagrams, the individual parts of neurons - axons, dendrites and synapses - must be densely identified in 3-dimensional volumes of neuronal tissue. This is typically achieved by electron microscopy (Kornfeld and Denk, 2018), necessitating physical sectioning of the specimen either before or during the image acquisition process using ultrathin sectioning techniques or gallium or gas cluster ion beams (Denk and Horstmann, 2004; Hayworth et al., 2020; Kasthuri et al., 2015; Xu et al., 2017). Here, we demonstrate that X-ray ptychography (Pfeiffer, 2018), a coherent diffractive X-ray imaging technique, can faithfully acquire 3-dimensional images of metal-stained mouse neuronal tissue. Achieving high imaging quality requires minimization of the radiation damage to the sample, which we achieve by imaging at cryogenic temperatures and using specialised tomographic reconstruction algorithms (Odstrcil et al., 2019b). Using a newly identified tri-functional epoxy resin we demonstrate radiation resistance to X-ray doses exceeding 1011Gy. Sub-40 nm resolution makes it possible to densely resolve axon bundles, boutons, dendrites, and synapses without physical sectioning. Moreover, the tissue volumes can subsequently be imaged in 3D using high-resolution focused ion beam scanning electron microscopy (FIB-SEM) (Heymann et al., 2006; Knott et al., 2008) showing intact ultrastructure, suggesting that metal-stained neuronal tissue can be highly radiation-stable. Ongoing improvements in synchrotron, X-ray and detector physics (Yabashi and Tanaka, 2017), as well as further optimization of sample preparation and staining procedures (Hua et al., 2015; Karlupia et al., 2023; Lu et al., 2023; Mikula and Denk, 2015; Pallotto et al., 2015; Song et al., 2022), could lead to substantial improvements in acquisition speed (Du et al., 2021), whilst widening the volumes that can be imaged with X-ray techniques using laminography (Helfen et al., 2005; Helfen et al., 2013; Holler et al., 2020b; Holler et al., 2019) and nano-holotomography (Cloetens et al., 1999; Kuan et al., 2020) could allow for non-destructive X-ray imaging of synapses and neural circuits contained in volumes of increasing size.

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Section: Discussionmentioning

confidence: 99%

Non-destructive X-ray tomography of brain tissue ultrastructure

Bosch,

Aidukas,

Holler

et al. 2023

Preprint

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“…It was published in the corresponding conference proceedings (SPIE Optics and Photonics 2022: Developments in X-Ray Tomography XIV). 48 Apart from that, there are no relevant financial interests in the paper and no other potential conflicts of interest to disclose.…”

Section: Disclosuresmentioning

confidence: 99%

“…An earlier version of this work was presented at SPIE Optics and Photonics 2022 as contribution 12242-3 “Neodymium acetate as a contrast agent for X-ray phase-contrast tomography” (presentation date: August 22, 2022). It was published in the corresponding conference proceedings (SPIE Optics and Photonics 2022: Developments in X-Ray Tomography XIV) 48 . Apart from that, there are no relevant financial interests in the paper and no other potential conflicts of interest to disclose.…”

Section: Disclosuresmentioning

confidence: 99%

Neodymium acetate as a contrast agent for X-ray phase-contrast tomography

Reichmann,

Ruhwedel,

Möbius

et al. 2023

J. Med. Imag.

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.PurposeX-ray phase-contrast tomography (XPCT) is a non-destructive, three-dimensional imaging modality that provides higher contrast in soft tissue than absorption-based CT and allows one to cover the cytoarchitecture from the centi- and millimeter scale down to the nanoscale. To further increase contrast and resolution of XPCT, for example, in view of addressing connectivity issues in the central nervous system (CNS), metal staining is indispensable. However, currently used protocols, for example, based on osmium and/or uranium are less suited for XPCT, due to an excessive β / δ-ratio. In this work, we explore the suitability of different staining agents for XPCT. Particularly, neodymium(III)-acetate (NdAc), which has recently been proposed as a non-toxic, non-radioactive easy to use alternative contrast agent for uranyl acetate (UAc) in electron microscopy, is investigated. Due to its vertical proximity to UAc in the periodic table, similar chemical but better suited optical properties for phase contrast can be expected.ApproachDifferently stained whole eye samples of wild type mouse and tissues of the CNS are embedded into EPON epoxy resin and scanned using synchrotron as well as with laboratory radiation. Phase retrieval is performed on the projection images, followed by tomographic reconstruction, which enables a quantitative analysis based on the reconstructed electron densities. Segmentation techniques and rendering software is used to visualize structures of interest in the sample.ResultsWe show that staining neuronal samples with NdAc enhances contrast, in particular for laboratory scans, allowing high-resolution imaging of biological soft tissue in-house. For the example of murine retina, specifically rods and cones as well as the sclera and the Ganglion cell layer seem to be targeted by the stain. A comparison of electron density by the evaluation of histograms allowed to determine quantitative measures to describe the difference between the examined stains.ConclusionThe results suggest NdAc to be an effective stain for XPCT, with a preferential binding to anionic groups, such as phosphate and carboxyl groups at cell surfaces, targeting certain layers of the retina with a stronger selectivity compared to other staining agents. Due to the advantageous X-ray optical properties, the stain seems particularly well-suited for phase contrast, with a comparably small number density and an overall superior image quality at laboratory sources.

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“…Note High-Resolution Neuroimaging by XPCT that the diameter of the biopsy punches would clearly allow a reduction of E by at least a factor of two. Future extension of this work may also include recently developed X-ray stains [32][33][34][35] to improve contrast not only for distinct structural hallmarks of neurodegeneration covered in this work, but also for the individual cellular components e.g. axons, dendrites or synapses, or the myelin sheath which would open up a new perspective for X-ray imaging of myelin-associated diseases, such as multiple sclerosis.…”

Section: Quantitative Comparison Of Electron Densitiesmentioning

confidence: 99%

3D imaging of neuronal inclusions and protein aggregates in human neurodegeneration by multiscale X-ray phase-contrast tomography

Reichmann,

Franz,

Eckermann

et al. 2024

Preprint

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This study leverages X-ray phase-contrast tomography (XPCT) for detailed analysis of neurodegenerative diseases like Alzheimer's and Parkinson's, focusing on the 3D visualization and quantification of neuropathological features within fixed human postmortem tissue. XPCT, utilizing synchrotron radiation, offers micrometer resolution, enabling the examination of intraneuronal aggregates-Lewy bodies, granulovacuolar degeneration, Hirano bodies, and neurofibrillary tangles-and extracellular amyloid plaques and cerebral amyloid angiopathy in the fixed human tissue. This approach surpasses aspects of traditional histology, integrating with neuropathology workflows for the identification and high-resolution study of these features. It facilitates correlative studies and quantitative electron density assessments, providing insights into the structural composition and distribution of neurodegenerative pathologies.

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Neodymium acetate as a contrast agent for x-ray phase-contrast tomography

Cited by 3 publications

References 41 publications

Non-destructive X-ray tomography of brain tissue ultrastructure

Non-destructive X-ray tomography of brain tissue ultrastructure

Neodymium acetate as a contrast agent for X-ray phase-contrast tomography

3D imaging of neuronal inclusions and protein aggregates in human neurodegeneration by multiscale X-ray phase-contrast tomography

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