We present Biomedisa, a free and easy-to-use open-source online platform developed for semi-automatic segmentation of large volumetric images. The segmentation is based on a smart interpolation of ...sparsely pre-segmented slices taking into account the complete underlying image data. Biomedisa is particularly valuable when little a priori knowledge is available, e.g. for the dense annotation of the training data for a deep neural network. The platform is accessible through a web browser and requires no complex and tedious configuration of software and model parameters, thus addressing the needs of scientists without substantial computational expertise. We demonstrate that Biomedisa can drastically reduce both the time and human effort required to segment large images. It achieves a significant improvement over the conventional approach of densely pre-segmented slices with subsequent morphological interpolation as well as compared to segmentation tools that also consider the underlying image data. Biomedisa can be used for different 3D imaging modalities and various biomedical applications.
A powerful two-frequency lidar system using polarized beams has been developed at YerPhI. The system is completed with laser beam polarization changers and nitrogen and water Raman channels for ...investigation of the influence of atmospheric electric fields on the elastic and Raman backscattered beams polarization. At present, the system is being tuned for measuring vertical atmospheric backscatter profiles of aerosols and hydrometeors, analyze the depolarization ratio of elastic backscattered laser beams and investigate the influence of external factors on the beam polarization. Laser light that is reflected from the air and from clouds carries information on density profiles, aerosols and electrical fields. Applications of this system will be the investigation of the electrical state of the atmosphere during thunderstorms 1-3 on Mt Aragats, and, possibly the monitoring of the atmosphere at the site of the upcoming Cherenkov Telescope Array (CTA). CTA is expected to provide unprecedented sensitivity for gamma ray detection in the energy range of 30 GeV to 300 TeV. To fully exploit the potential of the telescope system it is important to characterize the optical and electrical properties of the atmosphere. A lidar system for the continuous monitoring of the atmosphere is the tool of choice.
A high-time resolution Neutron Monitor Database (NMDB) has started to be realized in the frame of the Seventh Framework Programme of the European Commission. This database will include cosmic ray ...data from at least 18 neutron monitors distributed around the world and operated in real-time. The implementation of the NMDB will provide the opportunity for several research applications most of which will be realized in real-time mode. An important one will be the establishment of an Alert signal when dangerous solar cosmic ray particles are heading to the Earth, resulting into ground level enhancements effects registered by neutron monitors. Furthermore, on the basis of these events analysis, the mapping of all ground level enhancement features in near real-time mode will provide an overall picture of these phenomena and will be used as an input for the calculation of the ionization of the atmosphere. The latter will be useful together with other contributions to radiation dose calculations within the atmosphere at several altitudes and will reveal the absorbed doses during flights. Moreover, special algorithms for anisotropy and pitch angle distribution of solar cosmic rays, which have been developed over the years, will also be set online offering the advantage to give information about the conditions of the interplanetary space. All of the applications will serve the needs of the modern world which relies at space environment and will use the extensive network of neutron monitors as a multi-directional spectrographic detector. On top of which, the decreases of the cosmic ray intensity – known as Forbush decreases – will also be analyzed and a number of important parameters such as galactic cosmic ray anisotropy will be made available to the users of NMDB. A part of the NMDB project is also dedicated to the creation of a public outreach website with the scope to inform about cosmic rays and their possible effects on humans, technological systems and space-terrestrial environment. Therefore, NMDB will also stand as an informative gate on space research through neutron monitor’s data usage.
Abstract
Left atrial (LA) dimensions, wall composition and function strongly depend on left ventricular (LV) diastolic function and impaired in patients with preclinical diastolic disfunction (PDD), ...which increases the likelihood of atrial fibrillation (AF) occurrence. LA longitudinal strain (LALS) is a sensitive parameter of subclinical myocardial changes and its reduction might be predictive for AF.
Methods
168 patients (90 female) 68±9 years with arterial hypertension in sinus rhythm with preserved systolic function (LVEF>50%) and PDD and without renal or valvular disease and 45 age and sex matched healthy controls were followed up for 2 years. PDD was diagnosed at stress echocardiography (SE) if E/e' ≥13, transmittal E wave deceleration time reduction >50ms, systolic pulmonary artery pressure (sPAP) >30 mmHg, and patients remained asymptomatic. LALS was measured by speckle tracking echocardiography as average value of two basal segments in 4 chamber view along with LA end-systolic volume index (LAVi), LA EF, LV mass index (LVMi), and LVLS. 72 hours Holter monitoring was performed every 6 months.
Results
Patients with PDD had larger LAVi, less LALS, higher LVLS and bigger LVMi compared with controls (LAVi 30.5±4.9 ml/m2 vs 23.1±4.8 ml/m2, p<0.001; LALS 34.7±6.9% vs 45±4.3%, p<0.001; LVLS –17.4±2.4% vs –20.8±2.1%, p<0.002; LVMi 81.8±12.3 g/m2 vs 68±9.2 g/m2, p<0.001). AF was registered in 42 (25%) patients with PDD. LAVi, LVLS and LVMi did not significantly differ in PDD patients with or without incidents of AF however LALS was significantly less in patients with AF (26.8±7.5% vs 37.2±8.1%, p<0.01). Multivariate analysis defined LALS as an independent predictor of AF development (OR=2.4; 95% CI=2.41–5.96; p<0.01) with the cut-off value of 28.9%.
Conclusion
LA peak reservoir LS is an independent predictor of AF development in patients with PDD.
Abstract
Mitral regurgitation (MR) leads to subclinical changes that often cannot be detected by low sensitive conventional parameters and early predictors of deterioration could suggest a better ...timing for intervention.
Methods
We follow up 175 asymptomatic patients 56±13 years (79 female) with severe primary MR in sinus rhythm and without diabetes mellitus and renal disease for 2 years. Global longitudinal strain (LS) of left ventricle (LVGLS), right ventricular (RV) free wall LS (RVLS), and left atrial (LA) peak reservoir LS as average of two basal segments in 4 chamber view were measured by speckle tracking along with indexes of LV end-systolic and end-diastolic volumes, LV ejection fraction (EF), left atrial end-systolic volume index (LAVi) every 6 months. Normal reference values of LS were obtained from age and sex matched 40 healthy controls.
Results
Patients with MR had higher LV ejection fraction (EF), LVGLS, LALS and lower values of RVLS compared with controls (EF 67.4±5% vs 59.3±4%, p<0.05; LVGLS –25.2±2.3% vs –21.2±1.9%, p<0.03; LALS 46.2±5.1% vs 42.4±3.7%, p<0.04; RVLS –23.4±5.1% vs –27.3±2.8%, p<0.03). 53 (30%) patients developed symptoms at exercise during follow up. Symptomatic patients at baseline had higher values of RVLS compared with patients who remained asymptomatic during follow up without significant differences in EF, LVGLS, LALS (RVLS –21.4±2.6% vs –25.8±3.2%, p<0.02; EF 66.8±2.4% vs 68.1±3.1%, p>0.05; LVGLS –24.8±2.1% vs –25.3±2.3%, p>0.05; LALS 45.7±4.1% vs 46.5±4.4%, p>0.05). RVLS correlated with LAVi (r=0.53, p<0.01) and LALS (r=0.57, p<0.01). Regression analysis defined RVLS as an independent predictor of symptoms development (OR=3.2; 95% CI=1.37–7.63; p<0.01).
Conclusion
RV longitudinal strain predicts symptoms in patients with chronic primary mitral regurgitation.
Abstract
Preclinical diastolic disfunction (PDD) often progresses to heart failure and distinct clinical predictors for this transformation are yet to be defined. Since deterioration of longitudinal ...strain (LS) can occur before the changes of more conventional parameters, we assumed that right ventricular free wall longitudinal strain (RVLS) might start deteriorating before the pulmonary hypertension can be established.
Methods
We followed up 243 patients (143 female) 67±9 years with PDD for 3 years. All patients had an impaired relaxation or pseudo normal transmitral patterns and E/e' 8–13 at rest, normal NT-proBNP values, and systolic pulmonary artery pressure (sPAP) ≤30 mm Hg. PDD was diagnosed by stress echocardiography (SE) if E/e' ≥13, transmittal E wave deceleration time reduction >50ms, systolic pulmonary artery pressure (sPAP) <30 mmHg, and patients remained asymptomatic during SE. RVLS as average of RV free wall 3 segments values, left atrial peak reservoir LS (LALS) as average of two LA basal segments in four chamber view and left ventricular peak systolic global LS (LVGLS) were measured by speckle tracking (ST). ST and SE was performed with 6 months intervals. 35 healthy subject served as controls.
Results
Patients with PDD had higher RVLS, LVGLS, and lower LALS compared with controls (RVLS –23.2±4.2% vs –27.3±5.1%, p<0.001; LVGLS –17.8±5.2% vs –21.9±2.8%, p<0.001; LALS 39.7±3.7% vs 44.1±4.9%, p<0.002). 76 (31.3%) patients developed sPAP increase >30 mmHg at rest or SE during follow up of which 34 (44.7%) had dyspnea. Patients with increased sPAP had higher RVLS and lower LALS values at baseline compared with the rest of PDD patients without significant differences in other parameters (RVLS –17.9±2.8% vs –24.8±3.6%, p<0.002; LALS 37.7±2.3% vs 41.5±3.6%, p<0.003; LVGLS –17.4±4.8% vs –18.2±5.1%, p>0.05). Both LALS and RVLS correlated with LA end diastolic volume index (LALS r=0.51, p<0.01; RVLS r=0.54, p<0.01). Additionally RVLS was an independent predictor of sPAP rise (OR=2.7; 95% CI=2.43–6.92; p<0.01).
Conclusion
RVLS is an independent predictor of sPAP increase in patients with PDD.
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