Abstract A collection of more than 1800 carbonized papyri, discovered in the Roman ‘Villa dei Papiri’ at Herculaneum is the unique classical library survived from antiquity. These papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains an impressive amount of treatises by Greek philosophers and, especially, Philodemus of Gadara, an Epicurean thinker of 1st century BC. We read many portions of text hidden inside carbonized Herculaneum papyri using enhanced X-ray phase-contrast tomography non-destructive technique and a new set of numerical algorithms for ‘virtual-unrolling’. Our success lies in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of text have been decoded and the ‘voice’ of the Epicurean philosopher Philodemus is brought back again after 2000 years from Herculaneum papyri.
Phase-based (PB) x-ray imaging (XRI) methods have grown in importance over recent years, and it can probably be argued that the majority of micro-CT experiments at synchrotrons include phase effects in some form or fashion. A comparable if not higher level of interest has consequently arisen with regards to the translation of PB XRI into lab-based CT and micro-CT system, where however things have been moving more slowly, and the opposite is probably true i.e. most acquisitions are currently non-PB. The reasons for this are multiple and varied, but the key ones may be attributable to setup complexity and to the necessity to move optical elements during acquisitions, limits in spatial resolution, and excessively long acquisition times. In the imaging of biological tissues, especially in vivo, excessive delivered dose can pose an additional concern. Based on the acceptance that a “one size fits all solution” probably does not exist, and that most real world applications typically do not require all the above features simultaneously, our group has focused on the development of a flexible approach where typically counteracting features (e.g. high spatial resolution and fast acquisition times) can be traded off, including while making use of the same imaging system after this has been designed and built. This paper briefly reviews the technical innovations that have made the above possible, presents some key results in various areas of application, and discusses areas currently undergoing further development, among which are extensions to both higher and lower energy x-ray spectra, and new approaches to multimodality and data retrieval.
X-ray phase contrast imaging is gaining importance as an imaging tool. However, it is common for X-ray phase detection techniques to be sensitive to the derivatives of the phase. Therefore, the integration of differential phase images is a fundamental step both to access quantitative pixel content and for further analysis such as segmentation. The integration of noisy data leads to artefacts with a severe impact on image quality and on its quantitative content. In this work, an integration method based on the Wiener filter is presented and tested using simulated and real data obtained with the edge illumination differential X-ray phase imaging method. The method is shown to provide high image quality while preserving the quantitative pixel content of the integrated image. In addition, it requires a short computational time making it suitable for large datasets.
Introduction: In the study of neurodegenerative diseases, the possibility to follow the fate of specific cells or molecules within the whole body would be a milestone to better understand the complex evolution of disease mechanisms and to monitor the effects of therapies. The techniques available today do not allow the visualization of disease-relevant cells within the whole tridimensional biological context at high spatial resolution. Methods: Here we show the results from the first validation steps of a novel approach: by combining the conjugate nanobodies anti-glial fibrillary acidic protein (GFAP) and metal-nanoparticles (i.e. 2 nm gold NP) with X-ray phase contrast tomography (XPCT) we would be able to obtain a tridimensional visualization and identification of cells of interest together with the surrounding tissue and the vascular and neuronal networks. Results: By exploiting the X-ray attenuation properties of metal nanoparticles and the specific targeting capabilities of nanobodies, we could give XPCT the specificity it presently lacks, making it no longer a pure morphological but a molecular and targeted imaging technique. In our case, we synthesized and characterized Gold-NP/GFAP nanobody to target the astrocytes of mouse brain. Discussion: The results of the first tests presented in this paper have provided us with information on the feasibility of the approach, encouraging us to carry out further experiments in order to achieve the ultimate goal of setting up this new imaging technique.
The assessment of margin involvement is a fundamental task in breast conserving surgery to prevent recurrences and reoperations. It is usually performed through histology, which makes the process time consuming and can prevent the complete volumetric analysis of large specimens. X-ray phase contrast tomography combines high resolution, sufficient penetration depth and high soft tissue contrast, and can therefore provide a potential solution to this problem. In this work, we used a high-resolution implementation of the edge illumination X-ray phase contrast tomography based on "pixel-skipping" X-ray masks and sample dithering, to provide high definition virtual slices of breast specimens. The scanner was originally designed for intra-operative applications in which short scanning times were prioritised over spatial resolution; however, thanks to the versatility of edge illumination, high-resolution capabilities can be obtained with the same system simply by swapping x-ray masks without this imposing a reduction in the available field of view. This makes possible an improved visibility of fine tissue strands, enabling a direct comparison of selected CT slices with histology, and providing a tool to identify suspect features in large specimens before slicing. Combined with our previous results on fast specimen scanning, this works paves the way for the design of a multi-resolution EI scanner providing intra-operative capabilities as well as serving as a digital pathology system.
Oesophageal cancer is the 7th commonest cause of cancer death worldwide. Radiological staging of local oesophageal cancer is inaccurate. CT currently relies on attenuation of x-rays to generate contrast. Soft tissues have very similar attenuation properties so minimal contrast is generated. X-ray phase contrast imaging (XPCI) uses refraction of x-rays as they pass through tissue instead of attenuation and provides much higher soft tissue contrast. This technology can be tuned to a resolution of approximately 10 µm. This may allow for easy assessment of extent of disease infiltration. We aimed to use XPCI to image oesophagectomy specimens to assess pathological tumour and nodal stage for oesophageal cancer
Methods
Following ethical approval, 10 oesophagectomy specimens were obtained from patients having surgery for oesophageal cancers. These included both squamous and adenocarcinomas. Specimens were fixed in formalin for 12 hours. Sutures were placed through tissue to enable co-registration between CT slices and histology sections. For some scans, tissue was then dehydrated with graded ethanol for between 4.5 hours and 72 hours before being imaged. A Rigaku (MicroMax 007) xray source was used at 40 kV and 20 mA; a detector with 50µm pixel size; and sample and detector masks made of graphite substrate with gold overlay. Phase contrast was generated using edge illumination technique. We reconstructed the images using MATLAB® software. Specimens were returned for clinical histopathological assessment allowing correlation between H&E slides and CT images.
Results
We have performed 25 scans on 10 oesophagectomy samples and correlated them with histology Scans of samples in formalin failed to show adequate contrast between oesophageal layers to enable tumour visualisation and staging. Infiltrating the tissue with ethanol led to much better image contrast. We could easily identify mucosa, submucosa and both layers of muscle in reconstructed CT images. We also identified tumour infiltration through tissue layers and destruction of normal oesophageal morphology (figure 1). This was confirmed histologically and could be recognised by radiologists blinded to pathological staging This is the first time that XPCI has been used to image human oesophageal tissue. We have demonstrated the feasibility of the technique and the possibility of obtaining high resolution images which mimic histology with the extra benefit of demonstrating three dimensional structure.
Tissue engineering (TE) holds promise for generating lab-grown patient specific organs which can provide: (1) effective treatment for conditions that require volumetric tissue transplantation and (2) new platforms for drug testing. Even though volumetric structural information is essential for confirming successful organ maturation, TE protocol designs are currently informed through destructive and 2D construct assessment tools (e.g. histology). X-ray phase-contrast computed-tomography (PC-CT) can generate non-destructive, high resolution, 3D density maps of organ architecture. In this work, PC-CT is used as new imaging tool for guiding two TE protocols currently at the in-vitro testing stage. The first (1) involves cell-repopulation of an oesophageal scaffold, with the aim of using the regenerated construct for treating long-gap oesophageal atresia, whilst for the second (2) a lung-derived scaffold is populated with islets for regenerating a pancreas, with the "repurposed" lung offering a platform for diabetes drug testing. By combing 3D images and quantitative information, we were able to perform comprehensive construct evaluation. Specifically, we assessed volumetrically: (1) the cell-distribution within the regenerated oesophagi and (2) islet integration with the vascular tree of the lung-derived scaffold. This new information was proven to be essential for establishing corresponding TE protocols and enabled their progression to more advanced scale-up models. We are confident that PC-CT will provide the novel insights necessary to further progress TE protocols, with the next step being in-vivo testing. Crucially, the non-destructive nature of PC-CT will allow in-vivo assessments of TE constructs following their implantation into animal hosts, to investigate their successful integration.
Graphene grown on crystalline metal surfaces is a good candidate to act as a buffer layer between the metal and organic molecules that are deposited on top, because it offers the possibility to control the interaction between the substrate and the molecules. High-resolution angular-resolved ultraviolet photo electron spectroscopy (ARPES) is used to determine the interaction states of iron phthalocyanine molecules that are adsorbed onto graphene on Ni(111). The iron phthalocyanine deposition induces a quenching of the Ni d surface minority band and the appearance of an interface state on graphene/Ni(111). The results have been compared to the deposition of iron phthalocyanine on graphene/Ir(111), for which a higher decoupling of the organic molecule from the underlying metal is exerted by the graphene buffer layer.
We report on the development of a low-energy x-ray phase-based microscope using intensity-modulation masks for single-shot retrieval of three contrast channels: transmission, refraction, and ultra-small-angle scattering or dark field. The retrieval method is based on beam tracking, an incoherent and phase-based imaging approach. We demonstrate that the spatial resolution of this imaging system does not depend on focal spot size nor detector pixel pitch, as opposed to conventional and propagation-based x-ray imaging, and it is only dependent on the mask aperture size. This result enables the development of a multi-resolution microscope where multi-scale samples can be explored on different length scales by adjusting only the mask aperture size, without other modifications. Additionally, we show an extended capability of the system to resolve periodic structures below the resolution limit imposed by the mask apertures, which potentially extends dark-field imaging beyond its conventional use.
Characterizing nanoparticles (NPs) distribution in multiple and complex metastases is of fundamental relevance for the development of radiological protocols based on NPs administration. In the literature, there have been advances in monitoring NPs in tissues. However, the lack of 3D information is still an issue. X-ray phase-contrast tomography (XPCT) is a 3D label-free, non-invasive and multi-scale approach allowing imaging anatomical details with high spatial and contrast resolutions. Here an XPCT qualitative study on NPs distribution in a mouse brain model of melanoma metastases injected with gadolinium-based NPs for theranostics is presented. For the first time, XPCT images show the NPs uptake at micrometer resolution over the full brain. Our results revealed a heterogeneous distribution of the NPs inside the melanoma metastases, bridging the gap in spatial resolution between magnetic resonance imaging and histology. Our findings demonstrated that XPCT is a reliable technique for NPs detection and can be considered as an emerging method for the study of NPs distribution in organs.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
