Synchrotron X-ray imaging of soft biological tissues - principles, applications and future prospects.

Synchrotron-based tomographic phase-contrast X-ray imaging (SRµCT or SRnCT) is a versatile isotropic three-dimensional imaging technique that can be used to study biological samples spanning from single cells to human-sized specimens. SRµCT and SRnCT take advantage of the highly brilliant and coherent X-rays produced by a synchrotron light source. This enables fast data acquisition and enhanced image contrast for soft biological samples owing to the exploitation of phase contrast. In this Review, we provide an overview of the basics behind the technique, discuss its applications for biologists and provide an outlook on the future of this emerging technique for biology. We introduce the latest advances in the field, such as whole human organs imaged with micron resolution, using X-rays as a tool for virtual histology and resolving neuronal connections in the brain.

Distinct virtual histology of grey matter atrophy in four neuroinflammatory diseases.

Gray matter (GM) atrophies were observed in multiple sclerosis, neuromyelitis optica spectrum disorders (both anti-aquaporin-4 antibody-positive [AQP4+], and -negative [AQP4-] subtypes NMOSD), and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Revealing the pathogenesis of brain atrophy in these disorders would help their differential diagnosis and guide therapeutic strategies. To determine the neurobiological underpinnings of GM atrophies in multiple sclerosis, AQP4+ NMOSD, AQP4- NMOSD, and MOGAD, we conducted a virtual histology analysis that links T1-weighted image derived GM atrophy and gene expression using a multicenter cohort of 324 patients with multiple sclerosis, 197 patients with AQP4+ NMOSD, 75 patients with AQP4- NMOSD, 47 patients with MOGAD, and 2,169 healthy controls (HCs). First, interregional GM atrophy profiles across the cortical and subcortical regions were determined by Cohen's d between patients with multiple sclerosis, AQP4+ NMOSD, AQP4- NMOSD, MOGAD and HCs. Then, the GM atrophy profiles were spatially correlated with the gene expressions extracted from the Allen Human Brain Atlas, respectively. Finally, we explored the virtual histology of clinical feature relevant GM atrophy by subgroup analysis that stratified by physical disability, disease duration, number of relapses, lesion burden, and cognitive function. Multiple sclerosis showed severe widespread GM atrophy pattern, mainly involving subcortical nuclei and brainstem. AQP4+ NMOSD showed obvious widespread GM atrophy pattern, predominately located in occipital cortex as well as cerebellum. AQP4- NMOSD showed mild widespread GM atrophy pattern, mainly located in frontal and parietal cortices. MOGAD showed GM atrophy mainly involving the frontal and temporal cortices. High expression of genes specific to microglia, astrocytes, oligodendrocytes, and endothelial cells in multiple sclerosis, S1 pyramidal cells in AQP4+ NMOSD, as well as S1 and CA1 pyramidal cells in MOGAD had spatial correlations with GM atrophy profiles were observed, while no atrophy profile related gene expression was found in AQP4- NMOSD. Virtual histology of clinical feature relevant GM atrophy mainly pointed to the shared neuronal and endothelial cells among the four neuroinflammatory diseases. The unique underlying virtual histology patterns were microglia, astrocytes, and oligodendrocytes for multiple sclerosis; astrocytes for AQP4+ NMOSD; and oligodendrocytes for MOGAD. Neuronal and endothelial cells were shared potential targets across these neuroinflammatory diseases. These findings might help their differential diagnosis and optimal therapeutic strategies.

Three-dimensional virtual histology of the rat uterus musculature using micro-computed tomography.

Contractions of the uterus play an important role in menstruation and fertility, and contractile dysfunction can lead to chronic diseases such as endometriosis. However, the structure and function of the uterus are difficult to interrogate in humans, and thus animal studies are often employed to understand its function. In rats, anatomical studies of the uterus have typically been based on histological assessment, have been limited to small segments of the uterine structure, and have been time-consuming to reconstruct at the organ scale. This study used micro-computed tomography imaging to visualise the muscle structures in the entire non-pregnant rat uterus and assess its use for 3D virtual histology. An assessment of the rodent uterus is presented to (i) quantify muscle thickness variations along the horns, (ii) identify predominant fibre orientations of the muscles and (iii) demonstrate how the anatomy of the uterus can be mapped to 3D volumetric meshes via virtual histology. Micro-computed tomography measurements were validated against measurements from histological sections. The average thickness of the myometrium was found to be 0.33 ± 0.11 mm and 0.31 ± 0.09 mm in the left and right horns, respectively. The micro-computed tomography and histology thickness calculations were found to correlate strongly at different locations in the uterus: at the cervix, r = 0.87, and along the horn from the cervical end to the ovarian end, respectively, r = 0.77, r = 0.89 and r = 0.54, with p < 0.001 in every location. This study shows that micro-computed tomography can be used to quantify the musculature in the whole non-pregnant uterus and can be used for 3D virtual histology.

Coronary Artery Plaque Phenotype and 5-Year Clinical Outcomes in Older Patients with Non-ST Elevation Acute Coronary Syndrome.

Background: Lesions with thin-cap fibroatheroma (TCFA), small luminal area and large plaque burden (PB) have been considered at high risk of cardiovascular events. Older patients were not represented in studies which demonstrated correlation between clinical outcome and plaque characteristics. This study aims to investigate the prognostic role of high-risk plaque characteristics and long-term outcome in older patients presenting with non-ST elevation acute coronary syndrome (NSTEACS). Methods: This study recruited older patients aged ≥ 75 years with NSTEACS undergoing virtual-histology intravascular ultrasound (VH-IVUS) imaging from the Improve Clinical Outcomes in high-risk patieNts with acute coronary syndrome (ICON-1). Primary endpoint was the composite of major adverse cardiovascular events (MACE) consisting of all-cause mortality, myocardial infarction (MI), and any revascularisation. Every component of MACE and target vessel failure (TVF) including MI and any revascularisation were considered as secondary endpoints. Results: Eighty-six patients with 225 vessels undergoing VH-IVUS at baseline completed 5-year clinical follow-up. Patients with minimal lumen area (MLA) ≤ 4 mm 2 demonstrated increased risk of MACE (hazard ratio [HR] 2.37, 95% confidence interval [CI] 1.00-5.59, p = 0.048) with a worse event-free survival (Log Rank 4.17, p = 0.041) than patients with MLA > 4 mm 2 . Patients with combination of TCFA, MLA ≤ 4 mm 2 and PB ≥ 70% showed high risk of MI (HR 5.23, 95% CI 1.05-25.9, p = 0.043). Lesions with MLA ≤ 4 mm 2 had 6-fold risk of TVF (HR 6.16, 95% CI 1.24-30.5, p = 0.026). Conclusions: Small luminal area appears as the major prognostic factor in older patients with NSTEACS at long-term follow-up. Combination of TCFA, MLA ≤ 4 mm 2 and PB ≥ 70% was associated with high risk of MI. Clinical Trial Registration: NCT01933581.

The potential of x-ray virtual histology in the diagnosis of skin tumors.

BACKGROUND: Histopathological analysis represents the gold standard in clinical practice for diagnosing skin neoplasms. While the current diagnostic workflow has specialized in producing robust and accurate results, interpreting tissue architecture and malignant cellular morphology correctly remains one of the greatest challenges for pathologists. This paper aims to explore the prospect of applying x-ray virtual histology to human skin tumor excisions and correlating it with the histological validation. MATERIALS AND METHODS: Seven skin biopsies containing intriguing melanoma types and pigmented skin lesions were scanned using x-ray Computed micro-Tomography (µCT) and then sectioned for conventional histology assessment. RESULTS: The tissue microarchitecture reconstructed by µCT offers detailed insights into diagnosing the malignancy or benignity of the skin lesions. Three-dimensional reconstruction via x-ray virtual histology reveals infiltrative patterns in basal cell carcinoma and evaluated invasiveness in melanoma. The technology enables the identification of pagetoid distributions of neoplastic cells and the assessment of melanoma depth in three dimensions. CONCLUSION: Although the proposed approach is not intended to replace conventional histology, the non-destructive nature of the sample and the clarity provided by virtual inspection demonstrate the promising impact of µCT as a valid support method prior to conventional histological sectioning. Indeed, µCT images can suggest the optimal sectioning position before using a microtome, as is commonly performed in histological practice. Moreover, the three-dimensional nature of the proposed approach paves the way for a more accurate assessment of significant prognostic factors in melanoma, such as Breslow thickness, by considering the whole micro-volume rather than a two-dimensional observation.

Three-dimensional virtual histology of the human hippocampus based on phase-contrast computed tomography.

We have studied the three-dimensional (3D) cytoarchitecture of the human hippocampus in neuropathologically healthy and Alzheimer's disease (AD) individuals, based on phase-contrast X-ray computed tomography of postmortem human tissue punch biopsies. In view of recent findings suggesting a nuclear origin of AD, we target in particular the nuclear structure of the dentate gyrus (DG) granule cells. Tissue samples of 20 individuals were scanned and evaluated using a highly automated approach of measurement and analysis, combining multiscale recordings, optimized phase retrieval, segmentation by machine learning, representation of structural properties in a feature space, and classification based on the theory of optimal transport. Accordingly, we find that the prototypical transformation between a structure representing healthy granule cells and the pathological state involves a decrease in the volume of granule cell nuclei, as well as an increase in the electron density and its spatial heterogeneity. The latter can be explained by a higher ratio of heterochromatin to euchromatin. Similarly, many other structural properties can be derived from the data, reflecting both the natural polydispersity of the hippocampal cytoarchitecture between different individuals in the physiological context and the structural effects associated with AD pathology.

Case-control virtual histology elucidates cell types associated with cortical thickness differences in Alzheimer's disease.

Many neuropsychiatric disorders are characterised by altered cortical thickness, but the cell types underlying these changes remain largely unknown. Virtual histology (VH) approaches map regional patterns of gene expression with regional patterns of MRI-derived phenotypes, such as cortical thickness, to identify cell types associated with case-control differences in those MRI measures. However, this method does not incorporate valuable information of case-control differences in cell type abundance. We developed a novel method, termed case-control virtual histology (CCVH), and applied it to Alzheimer's disease (AD) and dementia cohorts. Leveraging a multi-region gene expression dataset of AD cases (n = 40) and controls (n = 20), we quantified AD case-control differential expression of cell type-specific markers across 13 brain regions. We then correlated these expression effects with MRI-derived AD case-control cortical thickness differences across the same regions. Cell types with spatially concordant AD-related effects were identified through resampling marker correlation coefficients. Among regions thinner in AD, gene expression patterns identified by CCVH suggested fewer excitatory and inhibitory neurons, and greater proportions of astrocytes, microglia, oligodendrocytes, oligodendrocyte precursor cells, and endothelial cells in AD cases vs. controls. In contrast, original VH identified expression patterns suggesting that excitatory but not inhibitory neuron abundance was associated with thinner cortex in AD, despite the fact that both types of neurons are known to be lost in the disorder. Compared to original VH, cell types identified through CCVH are more likely to directly underlie cortical thickness differences in AD. Sensitivity analyses suggest our results are largely robust to specific analysis choices, like numbers of cell type-specific marker genes used and background gene sets used to construct null models. As more multi-region brain expression datasets become available, CCVH will be useful for identifying the cellular correlates of cortical thickness across neuropsychiatric illnesses.

Growth of Neanderthal infants from Krapina (120-130 ka), Croatia.

Modern humans have a slow and extended period of childhood growth, but to what extent this ontogenetic pathway was present in Neanderthals is debated. Dental development, linked to the duration of somatic growth across modern primates, is the main source for information about growth and development in a variety of fossil primates, including humans. Studies of Neanderthal permanent teeth report a pace of development either similar to recent humans or relatively accelerated. Neanderthal milk teeth, which form and emerge before permanent teeth, provide an opportunity to determine which pattern was present at birth. Here we present a comparative study of the prenatal and early postnatal growth of five milk teeth from three Neanderthals (120 000-130 000 years ago) using virtual histology. Results reveal regions of their milk teeth formed quickly before birth and over a relatively short period of time after birth. Tooth emergence commenced towards the earliest end of the eruption schedules displayed by extant human children. Advanced dental development is consistent with expectations for Neanderthal infant feeding.

Multiscale X-ray phase contrast imaging of human cartilage for investigating osteoarthritis formation.

BACKGROUND: The evolution of cartilage degeneration is still not fully understood, partly due to its thinness, low radio-opacity and therefore lack of adequately resolving imaging techniques. X-ray phase-contrast imaging (X-PCI) offers increased sensitivity with respect to standard radiography and CT allowing an enhanced visibility of adjoining, low density structures with an almost histological image resolution. This study examined the feasibility of X-PCI for high-resolution (sub-) micrometer analysis of different stages in tissue degeneration of human cartilage samples and compare it to histology and transmission electron microscopy. METHODS: Ten 10%-formalin preserved healthy and moderately degenerated osteochondral samples, post-mortem extracted from human knee joints, were examined using four different X-PCI tomographic set-ups using synchrotron radiation the European Synchrotron Radiation Facility (France) and the Swiss Light Source (Switzerland). Volumetric datasets were acquired with voxel sizes between 0.7 × 0.7 × 0.7 and 0.1 × 0.1 × 0.1 µm3. Data were reconstructed by a filtered back-projection algorithm, post-processed by ImageJ, the WEKA machine learning pixel classification tool and VGStudio max. For correlation, osteochondral samples were processed for histology and transmission electron microscopy. RESULTS: X-PCI provides a three-dimensional visualization of healthy and moderately degenerated cartilage samples down to a (sub-)cellular level with good correlation to histologic and transmission electron microscopy images. X-PCI is able to resolve the three layers and the architectural organization of cartilage including changes in chondrocyte cell morphology, chondrocyte subgroup distribution and (re-)organization as well as its subtle matrix structures. CONCLUSIONS: X-PCI captures comprehensive cartilage tissue transformation in its environment and might serve as a tissue-preserving, staining-free and volumetric virtual histology tool for examining and chronicling cartilage behavior in basic research/laboratory experiments of cartilage disease evolution.

Three-dimensional virtual histology of human cerebellum by X-ray phase-contrast tomography.

To quantitatively evaluate brain tissue and its corresponding function, knowledge of the 3D cellular distribution is essential. The gold standard to obtain this information is histology, a destructive and labor-intensive technique where the specimen is sliced and examined under a light microscope, providing 3D information at nonisotropic resolution. To overcome the limitations of conventional histology, we use phase-contrast X-ray tomography with optimized optics, reconstruction, and image analysis, both at a dedicated synchrotron radiation endstation, which we have equipped with X-ray waveguide optics for coherence and wavefront filtering, and at a compact laboratory source. As a proof-of-concept demonstration we probe the 3D cytoarchitecture in millimeter-sized punches of unstained human cerebellum embedded in paraffin and show that isotropic subcellular resolution can be reached at both setups throughout the specimen. To enable a quantitative analysis of the reconstructed data, we demonstrate automatic cell segmentation and localization of over 1 million neurons within the cerebellar cortex. This allows for the analysis of the spatial organization and correlation of cells in all dimensions by borrowing concepts from condensed-matter physics, indicating a strong short-range order and local clustering of the cells in the granular layer. By quantification of 3D neuronal "packing," we can hence shed light on how the human cerebellum accommodates 80% of the total neurons in the brain in only 10% of its volume. In addition, we show that the distribution of neighboring neurons in the granular layer is anisotropic with respect to the Purkinje cell dendrites.

Three-dimensional virtual histology enabled through cytoplasm-specific X-ray stain for microscopic and nanoscopic computed tomography.

Many histological methods require staining of the cytoplasm, which provides instrumental details for diagnosis. One major limitation is the production of 2D images obtained by destructive preparation of 3D tissue samples. X-ray absorption micro- and nanocomputed tomography (microCT and nanoCT) allows for a nondestructive investigation of a 3D tissue sample, and thus aids to determine regions of interest for further histological examinations. However, application of microCT and nanoCT to biological samples (e.g., biopsies) is limited by the missing contrast within soft tissue, which is important to visualize morphological details. We describe an eosin-based preparation overcoming the challenges of contrast enhancement and selectivity for certain tissues. The eosin-based staining protocol is suitable for whole-organ staining, which then enables high-resolution microCT imaging of whole organs and nanoCT imaging of smaller tissue pieces retrieved from the original sample. Our results demonstrate suitability of the eosin-based staining method for diagnostic screening of 3D tissue samples without impeding further diagnostics through histological methods.

Virtual measurements of paracellular permeability and chronic inflammation via color coded pixel-wise T1 mapping.

To assess whether quantitative T1 relaxometry can measure permeability, chronic inflammation and mural thickening of mouse bladder wall. Adult female C57BL6 mice unexposed to radiation (controls) or 40 wk postirradiation of 10 Gy were scanned at 9.4 T before and after instillation (0.1 mL) of aqueous, novel contrast mixture (NCM) containing 4 mM gadobutrol and 5 mM ferumoxytol. Rapid acquisition with refocused echo (RARE) sequence was used with variable repetition times (TR). Pixel-wise maps of T1 relaxation times for the segmented bladder wall layers were generated from voxel-wise, nonlinear least square data fitting of TR-dependent signal intensity acquired with TR array of 0.4-10 s followed by the histology of harvested bladder. Significant differences between precontrast and postcontrast T1 (ΔT1) were noted in urothelium and lamina propria of both groups but only in detrusor of irradiated group (P < 0.001; 2-way ANOVA). Nearly twofold higher gadobutrol permeability (550 ± 73 vs. 294 ± 160 µM; P < 0.01) derived as per 1/ΔT1 = r1. [C] in urothelium of irradiated group. Inflammation and bladder wall thickening (0.75 ± 0. vs. 0.44 ± 0.08 mm; P < 0.001) predicted by MRI was subsequently confirmed by histology and altered expression of CD45 and zonula occludens-1 (ZO-1) relative to controls. NCM enhanced MRI relies on the retention of large molecular weight ferumoxytol in lumen for negative contrast, while permeation of the non-ionic, small molecular weight gadobutrol through ZO-1 generates positive contrast in bladder wall for virtual measurement of paracellular permeability and assessment of chronic inflammation in thin and distensible bladder wall, which is also defined by its variable shape and location within pelvis.

Maturation of the Human Cerebral Cortex During Adolescence: Myelin or Dendritic Arbor?

Previous in vivo studies revealed robust age-related variations in structural properties of the human cerebral cortex during adolescence. Neurobiology underlying these maturational phenomena is largely unknown. Here we employ a virtual-histology approach to gain insights into processes associated with inter-regional variations in cortical microstructure and its maturation, as indexed by magnetization transfer ratio (MTR). Inter-regional variations in MTR correlate with inter-regional variations in expression of genes specific to pyramidal cells (CA1) and ependymal cells; enrichment analyses indicate involvement of these genes in dendritic growth. On the other hand, inter-regional variations in the change of MTR during adolescence correlate with inter-regional profiles of oligodendrocyte-specific gene expression. Complemented by a quantitative hypothetical model of the contribution of surfaces associated with dendritic arbor (1631 m2) and myelin (48 m2), these findings suggest that MTR signals are driven mainly by macromolecules associated with dendritic arbor while maturational changes in the MTR signal are associated with myelination.

Imaging brain microstructure with diffusion MRI: practicality and applications.

This article gives an overview of microstructure imaging of the brain with diffusion MRI and reviews the state of the art. The microstructure-imaging paradigm aims to estimate and map microscopic properties of tissue using a model that links these properties to the voxel scale MR signal. Imaging techniques of this type are just starting to make the transition from the technical research domain to wide application in biomedical studies. We focus here on the practicalities of both implementing such techniques and using them in applications. Specifically, the article summarizes the relevant aspects of brain microanatomy and the range of diffusion-weighted MR measurements that provide sensitivity to them. It then reviews the evolution of mathematical and computational models that relate the diffusion MR signal to brain tissue microstructure, as well as the expanding areas of application. Next we focus on practicalities of designing a working microstructure imaging technique: model selection, experiment design, parameter estimation, validation, and the pipeline of development of this class of technique. The article concludes with some future perspectives on opportunities in this topic and expectations on how the field will evolve in the short-to-medium term.

Nondestructive adult age at death estimation: Visualizing cementum annulations in a known age historical human assemblage using synchrotron X-ray microtomography.

OBJECTIVES: Adult age at death estimation continues to challenge physical anthropologists. One estimation method involves counting tooth cementum annulations (TCA). Non-destructively accessing TCA is a critical step to approaching fossil teeth of unknown age and to verifying life history profiles of human ancestors. This pilot study aims to (a) non-destructively image TCA in teeth from a known age archeological human population by propagation phase contrast X-ray synchrotron µCT (PPC-SR-µCT) (b) test the correlation between real and estimated ages, and the accuracy, precision and bias of age estimates. MATERIALS AND METHODS: We examine 20 permanent human canines (aged 20-81 years), from a 18th to 19th century known age collection from St. Luke's Church (London, England). We scanned transverse segments of acellular cementum in the apical portion of the middle root third using PPC-SR-µCT. We generated virtual transverse sections on which two observers perform two sessions of blind TCA counts. We calculate the estimated ages at death by adding 10 years to the TCA counts. RESULTS: A moderately strong positive linear relationship exists between real and estimated ages (r = 0.76, p < .001), with an average inaccuracy of 16.1 years and an average bias towards underestimation of 15.7 years. This difference is lower in individuals <50 years (6.8 and 6.5 years, respectively, n = 10) compared with those >50 years (24.9 years, n = 10). DISCUSSION: We reliably imaged and identified TCA in individuals <50 years from a known-age archeological sample. Scanning refinement will yield a promising alternative to current destructive methods of TCA analyses and to aid access to life history events in adult fossil hominins.

[Association between Lipoprotein(a) and the characteristics of left main coronary artery plaque in patients with stable angina pectoris].

Objective: To investigate the relationship between Lipoprotein (LP) (a) level and the characteristics of tissue components of left main coronary artery (LMCA) plaque. Methods: A total of 102 patients with stable angina pectoris who underwent percutaneous coronary intervention (PCI) in the People's Hospital of Henan Province from June 2010 to October 2016 were included. We performed intravascular ultrasound-virtual histology (IVUS-VH) to their LMCAs and evaluated the tissue characteristics, and the blood level of total cholesterol (TC), triacylglycerol (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), ApoB, ApoA1, LP(a) were measured. According to the value of their LP(a) level they were divided into 2 groups (high LP(a) group (>300 mg/L) (n=35) and low LP(a) group (≤300 mg/L) (n=67)), then the relationship between the above lipid values and the tissue characteristics of the LMCA plaque in the patients were evaluated. Results: Patients with a high LP(a) had a larger percentage of fibrolipid volume and a smaller percentage fibrous volume compared to patients with a normal LP(a) (25%±5% vs 13%±6%, P<0.01 and 50%±8% vs 61%±9%, P<0.01). Using multivariate linear regression analysis after adjustment for the above-mentioned confounding factors, LP(a) had a significantly positive correlation with fibrolipid volume percentage (r=0.645, ß=0.29, P<0.01), and had a negative correlation with fibrous volume percentage (r=-0.467, ß=-0.32,P<0.01), suggesting that the LP(a) was associated with the vulnerability of the LMCA plaque. Conclusion: For the patients with stable angina pectoris, the LP(a) has a significantly positive correlation with the percentage of fibrolipid volume and a negative correlation with the percentage of fibrous volume, suggesting that the LP(a) could predict the vulnerability of the LMCA plaque.

[Intravascular ultrasound with virtual histology in assessment of atherosclerotic plaque composition in patients with coronary artery disease and type 2 diabetes mellitus].

Type 2 diabetes mellitus (T2DM) is a serious medical and social problem leading to early disability of patients and high mortality from cardiovascular complications. The development of cardiovascular events is associated not only with the degree of coronary artery stenosis, but also with the structure of the atherosclerotic plaque. AIM: This study aimed to characterize structure and composition of coronary artery atherosclerotic plaque in target lesion of T2DM patients and patients without diabetes using intravascular ultrasound (IVUS) and IVUS with virtual histology (IVUS-VH). MATERIALS AND METHODS: We observed 25 patients with coronary artery disease (CAD) with T2DM and without T2DM, which admitted to Endocrinology Research Centre to perform percutaneous coronary intervention (PCI). Patients with CAD and T2DM were included at group 1 and patients with CAD and without T2DM were included at group 2. IVUS and IVUS-VH assessment of target lesion were performed prior to stent implantation. We observed 24 plaques at group 1 and 10 plaques at group 2. RESULTS: In grey - scale IVUS 2D analysis there were no differences in mean cross - sectional area of the vessel (12.5 [10.4; 15.8] mm2 vs. 13.5 [12,7; 16.5] mm2; p=0.223, respectively) and lumen area (3.71 [2.5; 4.5] mm2 vs. 3.2 [2.7; 3.8] mm2; p=0.589, respectively). Plaque burden were higher in patients without T2DM (71.6 [65.5; 75.7] % vs. 77.6 [74.4; 80.4] %; p=0.008, respectively). IVUS-VH analysis showed that percent of necrotic core and dense calcium areas were significantly higher in the T2DM group (31.3 [25.3; 36.5] % vs. 21.65 [14.3; 27.8] %; p=0.01 and 4.7 [2.3; 7.8] % vs. 2.45 [1.2; 4.05] %; p=0.046, respectively). Percent of the fibrotic tissue were higher in non-T2DM group (55.35 [49.7; 63.6] % vs 67.7 [61.8; 76.5] %; p=0.004, respectively). There were no differences in percent of lipidic tissue in both groups. CONCLUSIONS: IVUS-VH assessment of coronary artery atherosclerotic plaques showed greater amount of necrotic core and dense calcium in patients with T2DM compared to patients without diabetes.

Virtual Histology in Everyday Gastrointestinal Endoscopy.

Advances in imaging technologies have demonstrated promise in the early detection of dysplasia and cancer. They have also provided the ability to assess submucosal and vascular structures, helping differentiate neoplastic from non-neoplastic tissue. The aim of this concise case-based review is to discuss how optical imaging can impact patient management decisions during endoscopy, using real- life scenarios.

Synchrotron inline phase contrast µCT enables detailed virtual histology of embedded soft-tissue samples with and without staining.

Synchrotron radiation micro-computed tomography (SRµCT) based virtual histology, in combination with dedicated ex vivo staining protocols and/or phase contrast, is an emerging technology that makes use of three-dimensional images to provide novel insights into the structure of tissue samples at microscopic resolution with short acquisition times of the order of minutes or seconds. However, the high radiation dose creates special demands on sample preparation and staining. As a result of the lack of specific staining in virtual histology, it can supplement but not replace classical histology. Therefore, the aim of this study was to establish and compare optimized ex vivo staining and acquisition protocols for SRµCT-based virtual histology of soft-tissue samples, which could be integrated into the standard workflow of classical histology. The high grade of coherence of synchrotron radiation allows the application of propagation-based phase contrast imaging (PBI). In this study, PBI yielded a strong increase in image quality even at lower radiation doses and consequently prevented any damage to the tissue samples or the embedding material. This work has demonstrated that the improvement in contrast-to-noise ratio by PBI enabled label-free virtual histology of soft-tissue specimens embedded in paraffin to a level of detail that exceeds that achieved with staining protocols.

Relationship between plaque composition by virtual histology intravascular ultrasound and clinical outcomes after percutaneous coronary intervention in saphenous vein graft disease patients: study protocol of a prospective cohort study.

BACKGROUND: Plaque composition and morphologic characteristics identified by virtual histology intravascular ultrasound (VH-IVUS) can determine plaques at increased risk of clinical events following percutaneous coronary intervention (PCI) among coronary artery disease (CAD) patients. However, there have been few studies to investigate the relationship between plaque composition of saphenous vein graft (SVG) by VH-IVUS and clinical outcomes in patients with saphenous vein graft disease (SVGD) undergoing PCI. The purpose of this study is to determine whether plaque components and characteristics by VH-IVUS can predict major adverse cardiac events (MACEs) among SVGD patients undergoing PCI. METHODS/DESIGN: This is a prospective cohort study conducted in Tianjin Chest Hospital, China. Participants with SVGD referred for PCI will be invited to participate in this study, and will be followed up at 1, 6, 12, 24 and 36 months post-PCI to assess clinical outcomes. The planned sample size is 175 subjects. We will recruit subjects with SVGD scheduled to receive PCI, aged 18-80 years, with a history of previous coronary artery bypass graft (CABG) surgery more than 1 year ago, and willing to participate in the study and sign informed consent. The composite primary study endpoint is the incidence of MACEs after PCI for SVGD, including death from cardiac causes, non-fatal myocardial infarction, unplanned target lesion revascularization (TLR) and target vessel revascularization (TVR). The primary outcome analysis will be presented as Kaplan-Meier estimates and the primary outcome analysis will be carried out using a Cox proportional hazards regression model. DISCUSSION: Once the predictive values of plaque components and characteristics by VH-IVUS on subsequent clinical outcomes are determined among SVGD patients undergoing PCI, an innovative prediction tool of clinical outcomes for SVGD patients undergoing PCI will be created, which may lead to the development of new methods of risk stratification and intervention guidance. TRIAL REGISTRATION: The study is registered to ClinicalTrials.gov (NCT03175952).