1,721,125 research outputs found
Cerebrovascular Reactivity MRI Protocol - Figures
No full textFigures describing an MRI protocol, including tolerability and reproducibility, for measurement of cerebrovascular reactivity
Magnetisation transfer saturation (MTsat) processing
No full textMATLAB processing script and functions for MTsat and MTR parametric maps with example dataset and processed output.York, Elizabeth; Thrippleton, Michael J; Waldman, Adam. (2020). Magnetisation transfer saturation (MTsat) processing, [software]. University of Edinburgh. Centre for Clinical Brain Sciences. https://doi.org/10.7488/ds/2965
Long-echo-time MR spectroscopic imaging in human brain at 1.5T and 3T
No full textFigures from article, "Variance components associated with long-echo-time MR spectroscopic imaging in human brain at 1.5T and 3T", accepted (December 2017) for publication in PlosONE.
Figure 1 shows a brain slice and associated spectra. Figure 2 shows variance components of MRS (subjects, visit, scan, voxel, residuals)
Authors: Michael J. Thrippleton*, Jehill P Parikh, Scott I K Semple, Bridget A Harris, Peter J D Andrews, Joanna M Wardlaw, Ian Marshal
MATLAB-based framework for simulating and processing BOLD CVR data
No full textCerebrovascular reactivity (CVR) is of interest in cerebrovascular diseases to assess the health of cerebral blood vessels. This software contains MATLAB scripts designed to simulate BOLD-CVR MRI experiments using hypercapnia administered through a block paradigm. This simulation framework models the BOLD response to hypercapnia as instantaneous. It can be used to study the effect of noise on the reliability of CVR estimates and compare different processing strategies.Sleight, Emilie; Thrippleton, Michael J. (2022). MATLAB-based framework for simulating and processing BOLD CVR data, [software]. University of Edinburgh. https://doi.org/10.7488/ds/3503
SUPERSEDED: 3D-printable phantoms for quantitative dynamic contrast-enhanced MRI
No full textThis dataset contains the experimental data and code required to reproduce results and figures in the article "3D-printable phantoms for quantitative dynamic contrast-enhanced MRI".
Abstract
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Purpose: A novel 3D-printed phantom design and methodology is proposed, addressing important requirements for technical validation, quality assurance and multi-site harmonisation of quantitative dynamic contrast-enhanced (DCE-) MRI measurements.
Methods: Phantoms were produced by 3D-printing gels incorporating channels and pores as proxies for blood vessels and extravascular extracellular space, respectively. A flow circuit was designed to reproduce clinically relevant arterial input functions (AIF). Using nine gels with variable porosity and channel size we evaluated the effect of 3D-printing parameters on DCE-MRI parameters obtained using the extended Tofts (ET) model. Physical gel and fitted model parameters were correlated by multiple linear regression.
Results: All phantoms generated realistic AIFs and tissue-like signal enhancement curves were accurately modelled by the ET model. As hypothesised, vp was positively associated with vchan (B = 0.86, p < 0.001) and showed a weaker, negative association with vpore (B = -0.18, p = 0.006); PS was positively associated with both vchan (B = 0.13 min-1, p < 0.001) and vpore (B = 0.051 min-1, p < 0.001). ve was positively associated with vpore (B = 0.89, p < 0.001) but not vchan. Fitted parameters were repeatable (coefficient of variation 2.1 - 3.2 %).
Conclusions: Tailorable 3D printed porous gel phantoms generating tissue-mimicking DCE-MRI signals have the potential to support validation, quality assurance and multi-site harmonisation of quantitative DCE-MRI.Refer to readme.txt file
3D-printable phantoms for quantitative dynamic contrast-enhanced MRI
No full textThis dataset contains the experimental data and code required to reproduce results and figures in the article "3D-printable phantoms for quantitative dynamic contrast-enhanced MRI" (final published version).
Abstract
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Purpose:
A novel 3D-printed phantom design and methodology is proposed, addressing important requirements for technical validation, quality assurance and multi-site harmonisation of quantitative dynamic contrast-enhanced (DCE-) MRI measurements.
Methods:
Phantoms were produced by 3D-printing gels incorporating channels and pores as proxies for blood vessels and extravascular extracellular space, respectively. A flow circuit was designed to reproduce clinically relevant arterial input functions (AIF). Using nine gels with variable porosity and channel size we evaluated the effect of 3D-printing parameters on DCE-MRI parameters obtained using the extended Tofts (ET) model. Physical gel and fitted model parameters were correlated by multiple linear regression.
Results:
All phantoms generated realistic AIFs and tissue-like signal enhancement curves were accurately modelled by the ET model. As hypothesised, vp was positively associated with vchan (B = 0.86, p < 0.001) and showed a weaker, negative association with vpore (B = -0.18, p = 0.006); PS was positively associated with both vchan (B = 0.13 min-1, p < 0.001) and vpore (B = 0.051 min-1, p < 0.001). ve was positively associated with vpore (B = 0.90, p < 0.001) but not vchan. Fitted parameters were repeatable (coefficient of variation 2.1 - 3.2 %).
Conclusions:
Tailorable 3D printed porous gel phantoms generating tissue-mimicking DCE-MRI signals have the potential to support validation, quality assurance and multi-site harmonisation of quantitative DCE-MRI.Refer to readme.txt file
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Preventing cognitive decline and dementia from cerebral small vessel disease: The LACI-1 Trial. Protocol and statistical analysis plan of a phase IIa dose escalation trial testing tolerability, safety and effect on intermediary endpoints of isosorbide mononitrate and cilostazol, separately and in combination
Full text linkRationale
The pathophysiology of most lacunar stroke, a form of small vessel disease, is thought to differ from large artery atherothrombo- or cardio-embolic stroke. Licensed drugs, isosorbide mononitrate and cilostazol, have promising mechanisms of action to support their testing to prevent stroke recurrence, cognitive impairment, or radiological progression after lacunar stroke.
Aim
LACI-1 will assess the tolerability, safety, and efficacy, by dose, of isosorbide mononitrate and cilostazol, alone and in combination, in patients with ischemic lacunar stroke.
Sample size
A sample of 60 provides 80+% power (significance 0.05) to detect a difference of 35% (90% versus 55%) between those reaching target dose on one versus both drugs.
Methods and design
LACI-1 is a phase IIa partial factorial, dose-escalation, prospective, randomized, open label, blinded endpoint trial. Participants are randomized to isosorbide mononitrate and/or cilostazol for 11 weeks with dose escalation to target as tolerated in two centers (Edinburgh, Nottingham). At three visits, tolerability, safety, blood pressure, pulse wave velocity, and platelet function are assessed, plus magnetic resonance imaging to assess cerebrovascular reactivity in a subgroup.
Study outcomes
Primary: proportion of patients completing study achieving target maximum dose.
Secondary
Symptoms whilst taking medications; safety (hemorrhage, recurrent vascular events, falls); blood pressure, platelet function, arterial stiffness, and cerebrovascular reactivity.
Discussion
This study will inform the design of a larger phase III trial of isosorbide mononitrate and cilostazol in lacunar stroke, whilst providing data on the drugs’ effects on vascular and platelet function
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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