scholarly journals Fixel-based Analysis of Diffusion MRI: Methods, Applications, Challenges and Opportunities

2020 ◽  
Author(s):  
Thijs Dhollander ◽  
Adam Clemente ◽  
Mervyn Singh ◽  
Frederique Boonstra ◽  
Oren Civier ◽  
...  
Keyword(s):  
Diffusion Mri ◽  
State Of The Art ◽  
Specific Information ◽  
Analysis Framework ◽  
Wide Range ◽  
Challenges And Opportunities ◽  
P Diffusion ◽  
Modelling Techniques ◽  
The Rich

Diffusion MRI has provided the neuroimaging community with a powerful tool to acquire in-vivo data sensitive to microstructural features of white matter, up to 3 orders of magnitude smaller than typical voxel sizes. The key to extracting such valuable information lies in complex modelling techniques, which form the link between the rich diffusion MRI data and various metrics related to the microstructural organisation. Over time, increasingly advanced techniques have been developed, up to the point where some diffusion MRI models can now provide access to properties specific to individual fibre populations in each voxel in the presence of multiple "crossing" fibre pathways. While highly valuable, such fibre-specific information poses unique challenges for typical image processing pipelines and statistical analysis. In this work, we review the "fixel-based analysis" (FBA) framework that implements bespoke solutions to this end, and has recently seen a stark increase in adoption for studies of both typical (healthy) populations as well as a wide range of clinical populations. We describe the main concepts related to fixel-based analyses, as well as the methods and specific steps involved in a state-of-the-art FBA pipeline, with a focus on providing researchers with practical advice on how to interpret results. We also include an overview of the scope of current fixel-based analysis studies (until August 2020), categorised across a broad range of neuroscientific domains, listing key design choices and summarising their main results and conclusions. Finally, we critically discuss several aspects and challenges involved with the fixel-based analysis framework, and outline some directions and future opportunities.

scholarly journals Comparison between diffusion MRI tractography and histological tract-tracing of cortico-cortical structural connectivity in the ferret brain

2019 ◽  
Vol 3 (4) ◽  
pp. 1038-1050 ◽  
Author(s):  
Céline Delettre ◽  
Arnaud Messé ◽  
Leigh-Anne Dell ◽  
Ophélie Foubet ◽  
Katja Heuer ◽  
...  
Keyword(s):  
Diffusion Mri ◽  
State Of The Art ◽  
Structural Connectivity ◽  
Ground Truth ◽  
Fiber Architecture ◽  
Tract Tracing ◽  
Central Focus ◽  
Highly Correlated ◽  
The Brain

The anatomical wiring of the brain is a central focus in network neuroscience. Diffusion MRI tractography offers the unique opportunity to investigate the brain fiber architecture in vivo and noninvasively. However, its reliability is still highly debated. Here, we explored the ability of diffusion MRI tractography to match invasive anatomical tract-tracing connectivity data of the ferret brain. We also investigated the influence of several state-of-the-art tractography algorithms on this match to ground truth connectivity data. Tract-tracing connectivity data were obtained from retrograde tracer injections into the occipital, parietal, and temporal cortices of adult ferrets. We found that the relative densities of projections identified from the anatomical experiments were highly correlated with the estimates from all the studied diffusion tractography algorithms (Spearman’s rho ranging from 0.67 to 0.91), while only small, nonsignificant variations appeared across the tractography algorithms. These results are comparable to findings reported in mouse and monkey, increasing the confidence in diffusion MRI tractography results. Moreover, our results provide insights into the variations of sensitivity and specificity of the tractography algorithms, and hence into the influence of choosing one algorithm over another.

scholarly journals Does powder averaging remove dispersion bias in diffusion MRI diameter estimates within real 3D axonal architectures?

2021 ◽  
Author(s):  
Mariam Andersson ◽  
Marco Pizzolato ◽  
Hans Martin Kjer ◽  
Katrine Forum Skodborg ◽  
Henrik Lundell ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Mri ◽  
Ex Vivo ◽  
Dynamic Properties ◽  
High Signal ◽  
Axon Diameter ◽  
Signal To Noise ◽  
B Values ◽  
Wide Range

Noninvasive estimation of axon diameter with diffusion MRI holds potential to investigate the dynamic properties of the brain network and pathology of neurodegenerative diseases. Recent methods use powder averaging to account for complex white matter architectures, such as fibre crossing regions, but these have not been validated for real axonal geometries. Here, we present 120-313 μm long segmented axons from X-ray nano-holotomography volumes of a splenium and crossing fibre region of a vervet monkey brain. We show that the axons in the complex crossing fibre region, which contains callosal, association, and corticospinal connections, are larger and exhibit a wider distribution than those of the splenium region. To accurately estimate the axon diameter in these regions, therefore, sensitivity to a wide range of diameters is required. We demonstrate how the q-value, b-value, signal-to-noise ratio and the assumed intra-axonal parallel diffusivity influence the range of measurable diameters with powder average approaches. Furthermore, we show how Gaussian distributed noise results in a wider range of measurable diameter at high b-values than with Rician distributed noise, even at high signal-to-noise ratios of 100. The number of gradient directions is also shown to impose a lower bound on measurable diameter. Our results indicate that axon diameter estimation can be performed with only few b-shells, and that additional shells do not improve the accuracy of the estimate. Through Monte Carlo simulations of diffusion, we show that powder averaging techniques succeed in providing accurate estimates of axon diameter across a range of sequence parameters and diffusion times, even in complex white matter architectures. At sufficiently low b-values, the acquisition becomes sensitive to axonal microdispersion and the intra-axonal parallel diffusivity shows time dependency at both in vivo and ex vivo intrinsic diffusivities.

scholarly journals Bringing diversity of experience into decision-making about surgery: developing an app for that

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Ilja Ormel ◽  
Susan Law ◽  
Michel Lortie ◽  
Charles Onu ◽  
Donna Tataryn
Keyword(s):  
Breast Cancer ◽  
Decision Making ◽  
Recommender System ◽  
Specific Information ◽  
Breast Cancer Patients ◽  
Women’S Experiences ◽  
Women's Experiences ◽  
Novel Approach ◽  
Wide Range ◽  
Challenges And Opportunities

ObjectiveTo design and pilot a mobile application to support decision-making about surgery for breast cancer patients, drawing from a collection of narratives from a diverse sample of Canadian women that used video/audio recordings (published on www.healthexperiences.ca). BackgroundThis idea came from the results of a larger research project where we collected a wide range of women’s stories about having breast cancer using qualitative research methods and video/audio recording. The women we interviewed for this project said that they felt overwhelmed by the amount of information in the period between diagnosis and surgery, and at the same time they felt they needed more specific information relevant to their needs, personal situation and preferences. They also wanted to learn from other women’s experiences of surgery. This project therefore aims to develop an information tool that can respond to that need by offering information in a more personalized manner. This project is funded by the QBCF [Quebec Breast Cancer Foundation]. MethodsSecondary analysis of existing data. Development of recommender system. Design and evaluation involving patients, clinicians and informatics experts. ResultsWe will present our analysis regarding women’s experiences related to surgery, decision-making, preferences and expectations, and need for experiential information. We will then present the development to date of a personalized information application using a computerized recommender system, including a summary of challenges and opportunities encountered along the way. ConclusionDeveloping reliable, evidence-based tools and electronic applications based on other peoples’ experiences offers a novel approach to support informed healthcare decision-making.

scholarly journals Neutrophils and Macrophages as Targets for Development of Nanotherapeutics in Inflammatory Diseases

Pharmaceutics ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1222
Author(s):  
Yujie Su ◽  
Jin Gao ◽  
Puneet Kaur ◽  
Zhenjia Wang
Keyword(s):  
Tissue Injury ◽  
Inflammatory Diseases ◽  
Current Status ◽  
Wide Range ◽  
Challenges And Opportunities ◽  
Potential Strategy ◽  
Novel Concept ◽  
Pathogen Clearance ◽  
Inflammation Responses

Neutrophils and macrophages are major components of innate systems, playing central roles in inflammation responses to infections and tissue injury. If they are out of control, inflammation responses can cause the pathogenesis of a wide range of diseases, such as inflammatory disorders and autoimmune diseases. Precisely regulating the functions of neutrophils and macrophages in vivo is a potential strategy to develop immunotherapies to treat inflammatory diseases. Advances in nanotechnology have enabled us to design nanoparticles capable of targeting neutrophils or macrophages in vivo. This review discusses the current status of how nanoparticles specifically target neutrophils or macrophages and how they manipulate leukocyte functions to inhibit their activation for inflammation resolution or to restore their defense ability for pathogen clearance. Finally, we present a novel concept of hijacking leukocytes to deliver nanotherapeutics across the blood vessel barrier. This review highlights the challenges and opportunities in developing nanotherapeutics to target leukocytes for improved treatment of inflammatory diseases.

Introduction: Rethinking Career Development

2021 ◽  
Author(s):  
Phil McCash ◽  
Tristram Hooley ◽  
Peter J. Robertson
Keyword(s):  
Career Development ◽  
Government Policy ◽  
Group Work ◽  
State Of The Art ◽  
Course Development ◽  
The Third ◽  
Wide Range ◽  
Life Course Development ◽  
The Rich ◽  
Selection Of

This chapter introduces readers to The Oxford Handbook of Career Development and to the field of career development. The origins of the field are discussed in relation to vocational guidance, differential psychology, interactionist sociology, and life course development. The selection of the term career development for this volume is explained with regard to three interlocking themes: the broader contexts of career development, including government policy; the wide range of theory concerned with career-related experiences, phenomena, and behaviour; and the broad spectrum of career helping practices, including one-to-one work and group work. The inspiration and aims for the volume are set out, and the challenges associated with terminology in the field are acknowledged. The editors seek to provide a state-of-the-art reference point for the field of career development, and engender a transdisciplinary and international dialogue that explores key current ideas, debates, and controversies. The volume is divided into three sections. The first explores the economic, educational, and public policy contexts for practice. The second section focuses on concepts and explores the rich theoretical landscape of the field. The third section turns to practice, and the translation of ideas into action to support individuals and groups with their career development.

scholarly journals Comparison between diffusion MRI tractography and histological tract-tracing of cortico-cortical structural connectivity in the ferret brain

2019 ◽  
Author(s):  
C. Delettre ◽  
A. Messé ◽  
L-A. Dell ◽  
O. Foubet ◽  
K. Heuer ◽  
...  
Keyword(s):  
Diffusion Mri ◽  
State Of The Art ◽  
Structural Connectivity ◽  
Ground Truth ◽  
Fiber Architecture ◽  
Tract Tracing ◽  
Central Focus ◽  
Highly Correlated ◽  
The Brain

AbstractThe anatomical wiring of the brain is a central focus in network neuroscience. Diffusion MRI tractography offers the unique opportunity to investigate the brain fiber architecture in vivo and non invasively. However, its reliability is still highly debated. Here, we explored the ability of diffusion MRI tractography to match invasive anatomical tract-tracing connectivity data of the ferret brain. We also investigated the influence of several state-of-the-art tractography algorithms on this match to ground truth connectivity data. Tract-tracing connectivity data were obtained from retrograde tracer injections into the occipital, parietal and temporal cortices of adult ferrets. We found that the relative densities of projections identified from the anatomical experiments were highly correlated with the estimates from all the studied diffusion tractography algorithms (Spearman’s rho ranging from 0.67 to 0.91), while only small, non-significant variations appeared across the tractography algorithms. These results are comparable to findings reported in mouse and monkey, increasing the confidence in diffusion MRI tractography results. Moreover, our results provide insights into the variations of sensitivity and specificity of the tractography algorithms and hence, into the influence of choosing one algorithm over another.

scholarly journals Troubling Pasts: Teaching Public History in Northern Ireland

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Olwen Purdue
Keyword(s):  
Northern Ireland ◽  
Public History ◽  
Cultural Landscape ◽  
The Public ◽  
Public Arena ◽  
Post Conflict ◽  
Wide Range ◽  
Challenges And Opportunities ◽  
The Rich ◽  
Forward Looking

Abstract This article explores the challenges and opportunities presented for the teaching and practice of public history in a post-conflict society that remains deeply divided over its past. It examines some of the negative ways in which history is used in the public arena, but also the potential of public history initiatives for building a more cohesive and forward-looking society. It examines how students can use the rich cultural landscape of Northern Ireland and engage with a wide range of experienced practitioners to learn more about the ways in which history divides; how we can negotiate these divisions over interpretations; how different communities understand, represent, and engage with their past; and why this matters.

A Color Coded STEM/SEM Image Storage System

1981 ◽  
Vol 39 ◽  
pp. 272-273
Author(s):  
Y. Kokubo ◽  
W. H. Hardy ◽  
J. Dance ◽  
K. Jones
Keyword(s):  
Image Processing ◽  
Electron Beam ◽  
Storage System ◽  
Particle Analysis ◽  
Specific Information ◽  
X Rays ◽  
Sem Image ◽  
Backscattered Electrons ◽  
Wide Range ◽  
Scanning Electron

A color coded digital image processing is accomplished by using JEM100CX TEM SCAN and ORTEC’s LSI-11 computer based multi-channel analyzer (EEDS-II-System III) for image analysis and display. Color coding of the recorded image enables enhanced visualization of the image using mathematical techniques such as compression, gray scale expansion, gamma-processing, filtering, etc., without subjecting the sample to further electron beam irradiation once images have been stored in the memory.The powerful combination between a scanning electron microscope and computer is starting to be widely used 1) - 4) for the purpose of image processing and particle analysis. Especially, in scanning electron microscopy it is possible to get all information resulting from the interactions between the electron beam and specimen materials, by using different detectors for signals such as secondary electron, backscattered electrons, elastic scattered electrons, inelastic scattered electrons, un-scattered electrons, X-rays, etc., each of which contains specific information arising from their physical origin, study of a wide range of effects becomes possible.

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

Ethnomedicinal uses, Phytochemistry and Pharmacological Aspects of the Genus Berberis Linn: A Comprehensive Review

2020 ◽  
Vol 23 ◽  
Author(s):  
Roohi Mohi-ud-din ◽  
Reyaz Hassan Mir ◽  
Prince Ahad Mir ◽  
Saeema Farooq ◽  
Syed Naiem Raza ◽  
...  
Keyword(s):  
Chemical Constituents ◽  
Pharmacological Activities ◽  
Traditional Use ◽  
Comprehensive Review ◽  
Wide Range ◽  
Anti Cancer ◽  
Comprehensive Survey ◽  
Ethnomedicinal Uses

Background: Genus Berberis (family Berberidaceae), which contains about 650 species and 17 genera worldwide, has been used in folklore and various traditional medicine systems. Berberis Linn. is the most established group among genera with around 450-500 species across the world. This comprehensive review will not only help researchers for further evaluation but also provide substantial information for future exploitation of species to develop novel herbal formulations. Objective: The present review is focussed to summarize and collect the updated review of information of Genus Berberis species reported to date regarding their ethnomedicinal information, chemical constituents, traditional/folklore use, and reported pharmacological activities on more than 40 species of Berberis. Conclusion: A comprehensive survey of the literature reveals that various species of the genus possess various phytoconstituents mainly alkaloids, flavonoid based compounds isolated from different parts of a plant with a wide range of pharmacological activities. So far, many pharmacological activities like anti-cancer, anti-hyperlipidemic, hepatoprotective, immunomodulatory, anti-inflammatory both in vitro & in vivo and clinical study of different extracts/isolated compounds of different species of Berberis have been reported, proving their importance as a medicinal plant and claiming their traditional use.

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