In vivo investigation of filter order influence in eigen-based clutter filtering for color flow imaging

Eigen-based adaptive filters have shown potential for providing a superior attenuation of clutter in color flow imaging. Critical for the success of this technique is the correct selection of filter order. In this work we review and compare filter order selection schemes for eigen-based filters in an in vivo context. Data was acquired from a thyroid tumor (PRF = 250 Hz, ensemble size = 12), where substantial tissue movement was present due to carotid artery pulsations, respiratory movements, and probe navigation. Eigen-filtering performance was evaluated for 1) an eigenvalue spectrum threshold, 2) a threshold on the ratio of successive eigenvalues, and 3) a threshold on eigenvector mean frequency estimated by the autocorrelation approach. Based on the observed eigenvalue and eigen-frequency distributions in analytical and in vivo examples, all filter order algorithms investigated suffered from potential pitfalls in specific Doppler scenarios. In the in vivo examples, the fixed order eigenfilter gave a sufficient suppression of clutter, but also removed substantial blood signal. Thresholding the ratio of eigenvalues better retained signal from blood, but also spurious artifacts was observed. The most consistent results were achieved by thresholding the mean frequency of the eigenvectors. The results demonstrate that given a suitable filter order algorithm, robust filtering can be achieved with the eigen-based approach. © 2007 IEEE.published_or_final_versio

Return to the workforce following first hospitalization for heart failure: a Danish nationwide cohort study

Background: Return to work is important financially, as a marker of functional status and for self-esteem in patients developing chronic illness. We examined return to work after first heart failure (HF) hospitalization. Methods: By individual-level linkage of nationwide Danish registries, we identified 21455 patients of working age (18-60 years) with a first HF hospitalization in the period of 1997-2012. Of these 11880 (55%) were in the workforce prior to HF hospitalization and comprised the study population. We applied logistic regression to estimate odds ratios (OR) for associations between age, sex, length of hospital stay, level of education, income, comorbidity and return to work. Results: One year after first HF hospitalization, 8040 (67.7%) returned to the workforce, 2981 (25.1%) did not, 805 (6.7%) died and 54 (0.5%) emigrated. Predictors of return to work included younger age (18-30 vs. 51-60 years, OR 3.12; 95% CI 2.42-4.03), male sex (OR 1.22 [1.18-1.34]) and level of education (long-higher vs. basic school OR 2.06 [1.63-2.60]). Conversely, hospital stay >7 days (OR 0.56 [0.51-0.62]) and comorbidity including history of stroke (OR 0.55 [0.45-0.69]), chronic kidney disease (OR 0.46 [0.36-0.59]), chronic obstructive pulmonary disease (OR 0.62 [0.52-0.75]), diabetes (OR 0.76 [0.68-0.85]) and cancer (OR 0.49 [0.40-0.61]) were all significantly associated with lower chance of return to work. Conclusions: Patients in the workforce prior to HF hospitalization had low mortality but high risk of detachment from the workforce one year later. Young age, male sex, and higher level of education were predictors of return to work

Local impact of perivascular plaques on cerebral blood flow dynamics in a transgenic mouse model of Alzheimer's disease.

Cerebrovascular pathology is closely coupled to cognitive function decline, as indicated by numerous studies at the system level. To better understand the mechanisms of this cognitive decline it is important to resolve how pathological changes in the vasculature - such as perivascular plaques - affect local cerebral blood flow dynamics. This issue is ideally studied in the intact brain at very high spatial resolution. Here, we describe initial results obtained by an approach based on in vivo observation by multi-photon microscopy of vascular plaques and local blood flow measurements in a transgenic mouse model engineered to express the human amyloid precursor protein with the Swedish and Arctic mutations. These mice exhibit a striking abundance of perivascular plaques in the cerebral cortex and are well suited to investigate vascular pathology in Alzheimer's disease

Risk of out-of-hospital cardiac arrest in patients with epilepsy and users of antiepileptic drugs

Aims: A few studies suggested that epilepsy and antiepileptic drugs with sodium channel-blocking properties were independently associated with out-of-hospital cardiac arrest (OHCA). However, these findings have not yet been replicated. Methods: Using Danish registries, we conducted a nested case–control study in a cohort of individuals between 1 June 2001 and 31 December 2015. Cases were defined as OHCA from presumed cardiac causes, and were matched with non-OHCA-controls based on sex, and age on the date of OHCA. Exposure of interest was epilepsy or antiepileptic drug use. To study the association between individual antiepileptic drug use and the rate of OHCA, we compared each antiepileptic drug with valproic acid. Cox regression with time-dependent covariates was conducted to calculate hazard ratio (HR) and 95% confidence interval (CI). Results: We identified 35 195 OHCA-cases and 351 950 matched non-OHCA controls. Epilepsy (cases: 3.58%, controls: 1.60%) was associated with increased rate of OHCA compared with the general population (HR: 1.76, 95%CI: 1.64–1.88) when common OHCA risk factors were taken into account. When we studied antiepileptic drug use, we found that 2 antiepileptic drugs without sodium channel blockage, clonazepam (HR: 1.88, 95%CI: 1.45–2.44) and pregabalin (HR: 1.33, 95%CI: 1.05–1.69), were associated with OHCA, whereas none of the antiepileptic drugs with sodium channel blockage were associated with OHCA. Conclusion: Epilepsy is associated with increased rate of OHCA. Our findings do not support a possible association between antiepileptic drugs with sodium channel-blocking properties and OHCA

Impact of proton pump inhibitor treatment on gastrointestinal bleeding associated with non-steroidal anti-inflammatory drug use among post-myocardial infarction patients taking antithrombotics: nationwide study

Study question What is the effect of proton pump inhibitors (PPIs) on the risk of gastrointestinal bleeding in post-myocardial infarction patients taking antithrombotics and treated with non-steroidal anti-inflammatory drugs (NSAIDs)? Methods This was a nationwide cohort study based on linked administrative registry data from all hospitals in Denmark between 1997 and 2011. The study included patients aged 30 years and over admitted with a first myocardial infarction who survived at least 30 days after discharge. The association between PPIs and risk of gastrointestinal bleeding according to NSAID plus antithrombotic therapy was estimated using adjusted time dependent Cox regression models. Study answer and limitations The use of PPIs was independently associated with decreased risk of gastrointestinal bleeding in post-myocardial infarction patients taking antithrombotics and treated with NSAIDs. Of 82 955 post-myocardial infarction patients (mean age 67.4 years, 64% (n=53 070) men), all of whom were taking single or dual antithrombotic therapy, 42.5% (n=35 233) filled at least one prescription for NSAIDs and 45.5% (n=37 771) received PPIs. Over a mean follow-up of 5.1 years, 3229 gastrointestinal bleeds occurred. The crude incidence rates of bleeding (events/100 person years) on NSAID plus antithrombotic therapy were 1.8 for patients taking PPIs and 2.1 for those not taking PPIs. The adjusted risk of bleeding was lower with PPI use (hazard ratio 0.72, 95% confidence interval 0.54 to 0.95) regardless of antithrombotic treatment regimen, type of NSAID, and type of PPI used. The main limitation of the study is its observational non-randomised design. The results suggest that PPI treatment probably has a beneficial effect regardless of underlying gastrointestinal risk and that when NSAIDs cannot be avoided in post-myocardial infarction patients, physicians might prescribe a PPI as well. The study does not clarify whether PPIs might be safely omitted in specific subgroups of patients with a low risk of gastrointestinal bleeding. What this study adds In post-myocardial infarction patients, bleeding complications have been associated with both antithrombotic and NSAID treatment. Concurrent use of PPIs was independently associated with a decreased risk of gastrointestinal bleeding in post-myocardial infarction patients taking antithrombotics and NSAID, regardless of antithrombotic treatment regimen, type of NSAID, and type of PPI used. Funding, competing interests, data sharing AMSO has received a grant from the Danish Council of Independent Research (grant 12-132760). GHG is supported by an unrestricted research scholarship from the Novo Nordisk Foundation

Associations between metabolic disorders and risk of cancer in Danish men and women:a nationwide cohort study

BACKGROUND: The prevalence of metabolic disorders is increasing and has been suggested to increase cancer risk, but the relation between metabolic disorders and risk of cancer is unclear, especially in young adults. We investigated the associations between diabetes, hypertension, and hypercholesterolemia on risk of all-site as well as site-specific cancers. METHODS: We consecutively included men and women from nationwide Danish registries 1996–2011, if age 20–89 and without cancer prior to date of entry. We followed them throughout 2012. Metabolic disorders were defined using discharge diagnosis codes and claimed prescriptions. We used time-dependent sex-stratified Poisson regression models adjusted for age and calendar year to assess associations between metabolic disorders, and risk of all-site and site-specific cancer (no metabolic disorders as reference). RESULTS: Over a mean follow-up of 12.6 (±5.7 standard deviations [SD]) years, 4,826,142 individuals (50.2 % women) with a mean age of 41.4 (±18.9 SD) years had 423,942 incident cancers. Incidence rate ratios (IRRs) of all-site cancer in patients with diabetes or hypertension were highest immediately following diagnosis of metabolic disorder. In women, cancer risk associated with diabetes continued to decline albeit remained significant (IRRs of 1.18–1.22 in years 1–8 following diagnosis). For diabetes in men, and hypertension, IRRs stabilized and remained significantly increased after about one year with IRRs of 1.10-1.13 in men for diabetes, and 1.07–1.14 for hypertension in both sexes. Conversely, no association was observed between hypercholesterolemia (treatment with statins) and cancer risk. The association between hypertension and cancer risk was strongest in young adults aged 20–34 and decreased with advancing age. CONCLUSIONS: Diabetes and hypertension were associated with increased risk of all-site cancer. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12885-016-2122-7) contains supplementary material, which is available to authorized users