Hyperpolarized (HP) 129Xe MRI uniquely images pulmonary ventilation, gas exchange, and terminal airway morphology rapidly and safely, providing novel information not possible using conventional ...imaging modalities or pulmonary function tests. As such, there is mounting interest in expanding the use of biomarkers derived from HP 129Xe MRI as outcome measures in multi‐site clinical trials across a range of pulmonary disorders. Until recently, HP 129Xe MRI techniques have been developed largely independently at a limited number of academic centers, without harmonizing acquisition strategies. To promote uniformity and adoption of HP 129Xe MRI more widely in translational research, multi‐site trials, and ultimately clinical practice, this position paper from the 129Xe MRI Clinical Trials Consortium (https://cpir.cchmc.org/XeMRICTC) recommends standard protocols to harmonize methods for image acquisition in HP 129Xe MRI. Recommendations are described for the most common HP gas MRI techniques—calibration, ventilation, alveolar‐airspace size, and gas exchange—across MRI scanner manufacturers most used for this application. Moreover, recommendations are described for 129Xe dose volumes and breath‐hold standardization to further foster consistency of imaging studies. The intention is that sites with HP 129Xe MRI capabilities can readily implement these methods to obtain consistent high‐quality images that provide regional insight into lung structure and function. While this document represents consensus at a snapshot in time, a roadmap for technical developments is provided that will further increase image quality and efficiency. These standardized dosing and imaging protocols will facilitate the wider adoption of HP 129Xe MRI for multi‐site pulmonary research.
Crowdsourcing Samples in Cognitive Science Stewart, Neil; Chandler, Jesse; Paolacci, Gabriele
Trends in cognitive sciences,
October 2017, 2017-Oct, 2017-10-00, 20171001, Letnik:
21, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Crowdsourcing data collection from research participants recruited from online labor markets is now common in cognitive science. We review who is in the crowd and who can be reached by the average ...laboratory. We discuss reproducibility and review some recent methodological innovations for online experiments. We consider the design of research studies and arising ethical issues. We review how to code experiments for the web, what is known about video and audio presentation, and the measurement of reaction times. We close with comments about the high levels of experience of many participants and an emerging tragedy of the commons.
In the next few years we estimate nearly half of all cognitive science research articles will involve samples of participants from Amazon Mechanical Turk and other crowdsourcing platforms.
We review the technical aspects of programming for the web and the resources available to experimenters.
Crowdsourcing of participants offers a ready and very different complement to the traditional college student samples, and much is now known about the reproducibility of findings with crowdsourced samples.
The population which we are sampling from is surprisingly small and highly experienced in cognitive science experiments, and this non-naïveté affects responses to frequently used measures.
The larger sample sizes that crowdsourcing affords bode well for addressing aspects of the replication crisis, but a possible tragedy of the commons looms now that cognitive scientists increasingly share the same participants.
We use computational modeling to examine the ability of evidence accumulation models to produce the reaction time (RT) distributions and attentional biases found in behavioral and eye-tracking ...research. We focus on simulating RTs and attention in binary choice with particular emphasis on whether different models can predict the late onset bias (LOB), commonly found in eye movements during choice (sometimes called the gaze cascade). The first finding is that this bias is predicted by models even when attention is entirely random and independent of the choice process. This shows that the LOB is not evidence of a feedback loop between evidence accumulation and attention. Second, we examine models with a relative evidence decision rule and an absolute evidence rule. In the relative models a decision is made once the difference in evidence accumulated for 2 items reaches a threshold. In the absolute models, a decision is made once 1 item accumulates a certain amount of evidence, independently of how much is accumulated for a competitor. Our core result is simple-the existence of the late onset gaze bias to the option ultimately chosen, together with a positively skewed RT distribution means that the stopping rule must be relative not absolute. A large scale grid search of parameter space shows that absolute threshold models struggle to predict these phenomena even when incorporating evidence decay and assumptions of either mutual inhibition or feedforward inhibition.
Stewart talks about building parliamentary networks which is a key objective for the Commonwealth Parliamentary Association (CPA) and the connections made at CPA programs can lead to further ...discussions across the Commonwealth. This example from The Scottish Parliament highlights the sharing of best practice on mental health support for Parliamentarians and parliamentary staff. The importance of maintaining positive mental health while working in a Legislature is something that he is personally involved in. For the past year he has been Co-Chair of the Scottish Parliament's Mental Health Network, which is one of several staff networks across the organization. The Network exists to promote positive mental health among staff of the Scottish Parliament, as well as Members and their staff, supporting Network members to be open and free to talk about issues of wellbeing.
Clozapine is among the most effective antipsychotics used for treatment resistant schizophrenia. Adverse reactions to clozapine include neutropenia. In March 2020, at the start of the Coronavirus −19 ...pandemic, clinicians raised concerns regarding continuation of antipsychotic treatment, and specifically of clozapine, in patients with coronavirus disease. We aimed here at providing a short report focusing on the association between neutropenia and clozapine in a case series of psychiatric inpatients diagnosed with COVID-19.
We retrospectively inspected data of 10 patients on clozapine, admitted to Highgate Mental Health Centre, Camden & Islington NHS Foundation Trust, between March and July 2020; selection was based on their COVID-19 positive PCR test. We used a linear regression model to estimate whether there was a significant drop in the neutrophil count during SARS-CoV-2 infection.
The analysis was done in R using a linear regression to the origin.
Data were collected on 10 patients, of which 7 were males. During COVID-19 infection, neutrophils’ count (ANC) was 4.13 × 109/l (SD = 2.70) which constituted a significant drop from a baseline value of 5.2 × 109/l (SD = 2.24). The mean relative reduction in ANC was −0.2729 (SD = 0.1666). The beta value of 0.8377 obtained with the linear regression showed that ANC values during SARS-CoV-2 infection were 83.77% of the baseline ANC showing that within the two time points there was a decrease of 16.23%. The linear regression had a pvalue = 8.96 × 10–8 and an adjusted R2 of 95.94% which shows that the variability of the data is very well explained by the model. We also compared baseline ANC with ANC values approximately a month after resolution of the infection and results indicate that ANC values return to a 95% of baseline.
Clinicians should bear in mind that a significant drop in neutrophils’ count may occur in patients taking clozapine and affected from a SARS-CoV-2 infectionand that this drop is only transitory.
•Clinicians raised concerns regarding continuation of clozapine in patients with coronavirus disease.•We inspected data of patients COVID positive taking clozapine between March and July 2020.•Absolute Neutrophil Count (ANC) dropped significantly with a 16.23% decrease of baseline values.•Following resolution of COVID-19 infection ANC values subsequently increased up to 95% of the pre-infection values.•A significant drop in neutrophils’ count may occur. However, this is likely to normalise once the infection is resolved.
To develop and assess a method for acquiring coregistered proton anatomical and hyperpolarized
Xe ventilation MR images of the lungs with compressed sensing (CS) in a single breath hold.
...Retrospective CS simulations were performed on fully sampled ventilation images acquired from one healthy smoker to optimize reconstruction parameters. Prospective same-breath anatomical and ventilation images were also acquired in five ex-smokers with an acceleration factor of 3 for hyperpolarized
Xe images, and were compared to fully sampled images acquired during the same session. The following metrics were used to assess data fidelity: mean absolute error (MAE), root mean square error, and linear regression of the signal intensity between fully sampled and undersampled images. The effect of CS reconstruction on two quantitative imaging metrics routinely reported percentage ventilated volume (%VV) and heterogeneity score was also investigated.
Retrospective simulations showed good agreement between fully sampled and CS-reconstructed (acceleration factor of 3) images with MAE (root mean square error) of 3.9% (4.5%). The prospective same-breath images showed a good match in ventilation distribution with an average R
of 0.76 from signal intensity linear regression and a negligible systematic bias of +0.1% in %VV calculation. A bias of -1.8% in the heterogeneity score was obtained.
With CS, high-quality 3D images of hyperpolarized
Xe ventilation (resolution 4.2 × 4.2 × 7.5 mm
) can be acquired with coregistered
H anatomical MRI in a 15-s breath hold. The accelerated acquisition time dispenses with the need for registration between separate breath-hold
Xe and
H MRI, enabling more accurate %VV calculation.
Purpose: High Mobility Group Box1 (HMGB1), which is one of the damage-associated molecular pattern molecules relating to various inflammatory diseases, has gained interest as a therapeutic target ...because of its involvement in wound healing processes. In the present study, we investigated HMGB1 as a potential therapeutic target in a model of lung fibrosis using a preclinical hyperpolarized 129Xe (HPXe) MRI system.Methods: Lung injury was induced by intra-peritoneal injection of bleomycin (BLM) in 19 mice. Three weeks post-injection (when fibrosis was confirmed histologically), administration of ethyl pyruvate (EP) and alogliptin (ALG), which are down- and up-regulators of HMGB1, respectively, was commenced in six and seven of the 19 mice, respectively, and continued for a further 3 weeks. A separate sham-instilled group was formed of five mice, which were administered with saline for 6 weeks. Over the second 3-week period, the effects of disease progression and pharmacological therapy in the four groups of mice were monitored by HPXe MRI metrics of fractional ventilation and gas-exchange function.Results: Gas-exchange function in BLM mice was significantly reduced after 3 weeks of BLM challenge compared to sham-instilled mice (P < 0.05). Ethyl pyruvate was found to improve HPXe MRI metrics of both ventilation and gas exchange, and repair tissue damage (assessed histologically), to a similar level as sham-instilled mice (P < 0.05), whilst ALG treatment caused no significant improvement of pulmonary function.Conclusion: This study demonstrates the down-regulator of HMGB1, EP, as a potential therapeutic agent for pulmonary fibrosis, as assessed by a non-invasive HPXe MRI protocol.
Commercial human MR scanners are optimised for proton imaging, containing sophisticated prescan algorithms with setting parameters such as RF transmit gain and power. These are not optimal for ...X-nuclear application and are challenging to apply to hyperpolarised experiments, where the non-renewable magnetisation signal changes during the experiment. We hypothesised that, despite the complex and inherently nonlinear electrodynamic physics underlying coil loading and spatial variation, simple linear regression would be sufficient to accurately predict X-nuclear transmit gain based on concomitantly acquired data from the proton body coil. We collected data across 156 scan visits at two sites as part of ongoing studies investigating sodium, hyperpolarised carbon, and hyperpolarised xenon. We demonstrate that simple linear regression is able to accurately predict sodium, carbon, or xenon transmit gain as a function of position and proton gain, with variation that is less than the intrasubject variability. In conclusion, sites running multinuclear studies may be able to remove the time-consuming need to separately acquire X-nuclear reference power calibration, inferring it from the proton instead.
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