Alzheimer's disease (AD) remains one of the foremost public health challenges of our time. Recently, attention has turned to the gut-brain axis, a complex network of communication between the gastrointestinal tract and the brain, as a potential player in the pathogenesis of AD. Here we exploited x-ray Phase Contrast Tomography to provide an in-depth analysis of the link between the gut condition and AD, exploring gut anatomy and structure in murine models. We conducted a comprehensive analysis by comparing the outcomes in various mouse models of cognitive impairment, including AD, frail mice, and frontotemporal dementia affected mice. We discovered an association between substantial changes in the gut structure and the presence of amyloid-beta (Aβ) in the brain. We found that the most important gut alterations are related to Aβ occurrence in the brain. In particular, we investigated the gut morphology, the distribution of enteric micro-processes and neurons in the ileum.
X-ray phase-contrast tomography (XPCT) offers a highly sensitive 3D imaging approach to investigate different disease-relevant networks from the single cell to the whole organ. We present here a concomitant study of the evolution of tissue damage and inflammation in potential target organs of the disease in the murine model of multiple sclerosis. XPCT identifies and monitors structural and cellular alterations throughout the central nervous system, but also in the gut and eye, of mice induced to develop multiple sclerosis-like disease and sacrificed at pre-symptomatic and symptomatic time points. This approach rests on a multiscale analysis to detect early appearance of imaging indicators potentially acting as biomarkers predictive of the disease. The longitudinal data permit an original evaluation of the sequential evolution of multi-organ damage in the mouse model, shedding light on the role of the gut-brain axis in the disease initiation and progression, of relevance for the human case.
The Hartmann wavefront sensor is able to measure, separately and in absolute, the real δ and imaginary parts β of the X-ray refractive index. While combined with tomographic setup, Hartmann sensor opens many interesting opportunities behind the direct measurement of the material density. In order to handle the different ways of using an X-ray wavefront sensor in imaging, we developed 3D wave propagation model based on Fresnel propagator. The model is made in a way to manage any degree of spatial coherence of the source, thus enabling to model accurately experiments using tabletop source, high harmonic generation, plasma-based soft X-ray laser, synchrotron or X-ray free-electron laser. Beam divergence is described in a physical manner consistent with the spatial coherence. The capabilities of the Hartmann wavefront sensor will be compared with experimental results from in-line X-ray Phase Contrast Tomography.
To date there have been only indirect indications of the presence of bound sodium accumulation in muscle and skin tissues. Despite their osmotic inactivity, such sodium deposits can effect on mechanical properties of the heart muscle impairing its elasticity and leading to serious heart dysfunctions. In this work an accurate study of the chemical composition of the heart muscle tissue at the cellular level was carried out using the methods of X-ray absorption and fluorescence microscopy. The experiments were carried out on a TwinMic X-ray scanning microscope [3] at ELETTRA synchrotron (Italy) with a resolution of about 1 μm. Comparison of the obtained maps of intra- and extracellular sodium distribution in heart tissues of different laboratory animals has resulted in the first experimental confirmation of the hypotheses about the existence of deposited sodium states in the intercellular space. The paper demonstrates an example of the state-of-the-art medical applications of high spectral brilliance X-ray sources.
Despite significant progress in computer vision, pattern recognition, and image analysis, artifacts in imaging still hampers the progress in many scientific fields relying on the results of image analysis. We here present an advanced image-based artifacts suppression algorithm for high-resolution tomography. The algorithm is based on guided filtering of a reconstructed image mapped from the Cartesian to the polar coordinates space. This postprocessing method efficiently reduces both ring- and radial streak artifacts in a reconstructed image. Radial streak artifacts can appear in tomography with an off-center rotation of a large object over 360 degrees used to increase the reconstruction field of view. We successfully applied the developed algorithm for improving x-ray phase-contrast images of human post-mortem pineal gland and olfactory bulbs.
The paper presents a novel method for suppression of the orthotropic stripe artifacts typical for sensitive optical detector arrays. The algorithm is based on the guided filtering technique where the guidance image is constructed from the input frame in a way that removes artifacts from local contrast structures while disregarding the low-frequency distortions. The artifact suppression procedure was applied to the images of human faces taken with the IR -- THz camera in the diagnosis of psycho-emotional states. In this case, the presence of orthotropic artifacts prevents digital image stabilization. We also demonstrated that adaptation of the alg
Computer vision for biomedical imaging applications is fast developing and at once demanding field of computer science. In particular, computer vision technique provides excellent results for detection and segmentation problems in tomographic imaging. X-ray phase contrast Tomography (XPCT) is a noninvasive 3D imaging technique with high sensitivity for soft tissues. Despite a considerable progress in XPCT data acquisition and data processing methods, the problem in degradation of image quality due to artifacts remains a widespread and often critical issue for computer vision applications. One of the main problems originates from a sample alteration during a long tomographic scan. We proposed and tested Simultaneous Iterative Reconstruction algorithm with Total Variation regularization to reduce the number of projections in high resolution XPCT scans of ex-vivo mouse spinal cord. We have shown that the proposed algorithm allows tenfold reducing the number of projections and, therefore, the exposure time, with conservation of the important morphological information in 3D image with quality acceptable for computer graphics and computer vision applications. Our research paves a way for more effective implementation of advanced computer technologies in phase contrast tomographic research.
Theranostics is an innovative research field that aims to develop high target specificity cancer treatments by administering small metal-based nanoparticles (NPs). This new generation of compounds exhibits diagnostic and therapeutic properties due to the high atomic number of their metal component. In the framework of a combined research program on low dose X-ray imaging and theranostic NPs, X-ray Phase Contrast Tomography (XPCT) was performed at ESRF using a 3 μm pixel optical system on two samples: a mouse brain bearing melanoma metastases injected with gadolinium NPs and, a mouse liver injected with gold NPs. XPCT is a non-destructive technique suitable to achieve the 3D reconstruction of a specimen and, widely used at micro-scale to detect abnormalities of the vessels, which are associated to the tumor growth or to the development of neurodegenerative diseases. Moreover, XPCT represents a promising and complementary tool to study the biodistribution of theranostic NPs in biological materials, thanks to the strong contrast with respect to soft tissues that metal-based NPs provide in radiological images. This work is relied on an original imaging approach based on the evaluation of the contrast differences between the images acquired below and above K-edge energies, as a proof of the certain localization of NPs. We will present different methods aiming to enhance the localization of NPs and a 3D map of their distribution in large volume of tissues.
The idea of an X-ray waveguide has its origin in 1974 from a paper of Spiller and Segmuller1, but only then years ago2-5
it has been demonstrated that a submicrometer X-ray beam could be produced by the waveguides. From the first
experiments up to now the efficiency has been improved by three orders of magnitude6, and a nanometer beam confined
in two directions has been also produced7. Recently, as it will be shown in this paper, the possibility to use waveguides
with laboratory sources has been also demonstrated. The unique characteristics of the beam produced by the waveguides
(nanometer beam size, high degree of coherence, well defined beam profile, etc.) make it appealing for several
applications in microimaging, microdiffraction, etc. In this work the principles of X-ray waveguides together with the
view of the present activity and applications of this optics will be presented.
We present in this paper the basic principle of novel X-ray optics composed of confocal nested reflecting mirrors that allows
more photons from a source of X-ray radiation to be accepted compared with a single mirror and that can be fabricated using
relatively cheap microfabrication tools. In order to optimize relevant parameters of the proposed system, we developed a ray-
tracing code for nested surfaces. The choice of parameters of the mirror system (length, position, eccentricity, etc.) is carried
out starting from theoretical considerations, which have been recently developed and, through simple equations, give optimal
parameters of X-ray mirrors providing a maximal acceptance angle of the system.
High energy x-ray phase contrast experiment with an unprecedent resolution is shown. The coherent and divergent submicron beam from an x-ray waveguide is used to realize a lensless microscope and to magnify spatial variations in optical path length 500 times or more. The defocused image of a nylon fiber with a resolution of 0.14 micron is presented. Exposure times as short as 0.1 seconds gave already visible contrast, opening the way to high resolution, real time studies.
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