729 research outputs found

    Face processing in adolescents with positive and negative threat bias

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    BackgroundIndividuals with anxiety disorders exhibit a ‘vigilance-avoidance’ pattern of attention to threatening stimuli when threatening and neutral stimuli are presented simultaneously, a phenomenon referred to as ‘threat bias’. Modifying threat bias through cognitive retraining during adolescence reduces symptoms of anxiety, and so elucidating neural mechanisms of threat bias during adolescence is of high importance. We explored neural mechanisms by testing whether threat bias in adolescents is associated with generalized or threat-specific differences in the neural processing of faces.MethodSubjects were categorized into those with (n = 25) and without (n = 27) threat avoidance based on a dot-probe task at average age 12.9 years. Threat avoidance in this cohort has previously been shown to index threat bias. Brain response to individually presented angry and neutral faces was assessed in a separate session using functional magnetic resonance imaging.ResultsAdolescents with threat avoidance exhibited lower activity for both angry and neutral faces relative to controls in several regions in the occipital, parietal, and temporal lobes involved in early visual and facial processing. Results generalized to happy, sad, and fearful faces. Adolescents with a prior history of depression and/or an anxiety disorder had lower activity for all faces in these same regions. A subset of results replicated in an independent dataset.ConclusionsThreat bias is associated with generalized, rather than threat-specific, differences in the neural processing of faces in adolescents. Findings may aid in the development of novel treatments for anxiety disorders that use attention training to modify threat bias.</jats:sec

    Lung function in children with Duchenne's muscular dystrophy

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    AbstractDuchenne's muscular dystrophy (DMD), characterized by gradually developing muscular weakness, leads to respiratory symptoms and reduced lung function. We aimed to assess lung function in 25 patients with DMD in relationship to age and muscular function. The 25 boys, mean age 13 years, comprized patients in southern Norway with DMD, taking part in an epidemiological follow-up study. None had chronic respiratory disease. Lung function was measured by maximum expiratory flow–volume loops and whole body plethysmography, and repeated after 1 year (n=14). Lung function was reduced compared to predicted values for healthy children. Forced expiratory volume in 1 sec (FEV1)% predicted and forced vital capacity (FVC)% predicted correlated (significantly) inversely to age. FEV1and FVC decreased annually 5·61 and 4·2% of predicted, respectively. Absolute values of FVC (litres) and FEV1(l sec−1) increased until mean age 14 years, decreasing thereafter. Values in % predicted decreased steadily throughout the age range (6–19 years). Lung function correlated closely to upper limb muscle function

    Recent trends and potential drivers of non-invasive cardiovascular imaging use in the United States of America and England

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    Background: Non-invasive Cardiovascular imaging (NICI), including cardiovascular magnetic resonance (CMR) imaging provides important information to guide the management of patients with cardiovascular conditions. Current rates of NICI use and potential policy determinants in the United States of America (US) and England remain unexplored. Methods: We compared NICI activity in the US (Medicare fee-for-service, 2011–2015) and England (National Health Service, 2012–2016). We reviewed recommendations related to CMR from Clinical Practice Guidelines, Appropriate Use Criteria (AUC), and Choosing Wisely. We then categorized recommendations according to whether CMR was the only recommended NICI technique (substitutable indications). Reimbursement policies in both settings were systematically collated and reviewed using publicly available information. Results: The 2015 rate of NICI activity in the US was 3.1 times higher than in England (31,055 vs. 9,916 per 100,000 beneficiaries). The proportion of CMR of all NICI was small in both jurisdictions, but nuclear cardiac imaging was more frequent in the US in absolute and relative terms. American and European CPGs were similar, both in terms of number of recommendations and proportions of indications where CMR was not the only recommended NICI technique (substitutable indications). Reimbursement schemes for NICI activity differed for physicians and hospitals between the two settings. Conclusions: Fee-for-service physician compensation in the US for NICI may contribute to higher NICI activity compared to England where physicians are salaried. Reimbursement arrangements for the performance of the test may contribute to the higher proportion of nuclear cardiac imaging out of the total NICI activity. Differences in CPG recommendations appear not to explain the variation in NICI activity between the US and England

    Minimising multi-centre radiomics variability through image normalisation:a pilot study

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    Radiomics is an emerging technique for the quantification of imaging data that has recently shown great promise for deeper phenotyping of cardiovascular disease. Thus far, the technique has been mostly applied in single-centre studies. However, one of the main difficulties in multi-centre imaging studies is the inherent variability of image characteristics due to centre differences. In this paper, a comprehensive analysis of radiomics variability under several image- and feature-based normalisation techniques was conducted using a multi-centre cardiovascular magnetic resonance dataset. 218 subjects divided into healthy (n = 112) and hypertrophic cardiomyopathy (n = 106, HCM) groups from five different centres were considered. First and second order texture radiomic features were extracted from three regions of interest, namely the left and right ventricular cavities and the left ventricular myocardium. Two methods were used to assess features' variability. First, feature distributions were compared across centres to obtain a distribution similarity index. Second, two classification tasks were proposed to assess: (1) the amount of centre-related information encoded in normalised features (centre identification) and (2) the generalisation ability for a classification model when trained on these features (healthy versus HCM classification). The results showed that the feature-based harmonisation technique ComBat is able to remove the variability introduced by centre information from radiomic features, at the expense of slightly degrading classification performance. Piecewise linear histogram matching normalisation gave features with greater generalisation ability for classification ( balanced accuracy in between 0.78 Âą 0.08 and 0.79 Âą 0.09). Models trained with features from images without normalisation showed the worst performance overall (balanced accuracy in between 0.45 Âą 0.28 and 0.60 Âą 0.22). In conclusion, centre-related information removal did not imply good generalisation ability for classification

    Risk factors for raised left ventricular filling pressure by cardiovascular magnetic resonance: prognostic insights

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    Background Cardiovascular magnetic resonance (CMR) imaging shows promise in estimating pulmonary capillary wedge pressure (PCWP) non-invasively. At the population level, the prognostic role of CMR-modelled PCWP remains unknown. Furthermore, the relationship between CMR-modelled PCWP and established risk factors for cardiovascular disease has not been well characterized. Objective The main aim of this study was to investigate the prognostic value of CMR-modelled PCWP at the population level. Methods Employing data from the imaging substudy of the UK Biobank, a very large prospective population-based cohort study, CMR-modelled PCWP was calculated using a model incorporating left atrial volume, left ventricular mass and sex. Logistic regression explored the relationships between typical cardiovascular risk factors and raised CMR-modelled PCWP (≥15 mmHg). Cox regression was used to examine the impact of typical risk factors and CMR-modelled PCWP on heart failure (HF) and major adverse cardiovascular events (MACE). Results Data from 39 163 participants were included in the study. Median age of all participants was 64 years (inter-quartile range: 58 to 70), and 47% were males. Clinical characteristics independently associated with raised CMR-modelled PCWP included hypertension [odds ratio (OR) 1.57, 95% confidence interval (CI) 1.44–1.70, P < 0.001], body mass index (BMI) [OR 1.57, 95% CI 1.52–1.62, per standard deviation (SD) increment, P < 0.001], male sex (OR 1.37, 95% CI 1.26–1.47, P < 0.001), age (OR 1.33, 95% CI 1.27–1.41, per decade increment, P < 0.001) and regular alcohol consumption (OR 1.10, 95% CI 1.02–1.19, P = 0.012). After adjusting for potential confounders, CMR-modelled PCWP was independently associated with incident HF [hazard ratio (HR) 2.91, 95% CI 2.07–4.07, P < 0.001] and MACE (HR 1.48, 95% CI 1.16–1.89, P = 0.002). Conclusions Raised CMR-modelled PCWP is an independent risk factor for incident HF and MACE. CMR-modelled PCWP should be incorporated into routine CMR reports to guide HF diagnosis and further management
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