Tracking the Endocardial Border in Artifact-Prone 3D Images

Echocardiography is a commonly-used, safe, and noninvasive method for assessing cardiac dysfunction and related coronary artery disease. The analysis of echocardiograms, whether visual or automated, has traditionally been hampered by the presence of ultrasound artifacts, which obscure the moving myocardial wall. In this study, a novel method is proposed for tracking the endocardial surface in 3D ultrasound images. Artifacts which obscure the myocardium are detected in order to improve the quality of cardiac boundary segmentation. The expectation-maximization algorithm is applied in a stationary and dynamic, cardiac-motion frame-of-reference, and weights are derived accordingly. The weights are integrated with an optical-flow based contour tracking method, which incorporates prior knowledge via a statistical model of cardiac motion. Evaluation on 35 three-dimensional echocardiographic sequences shows that this weighed tracking method significantly improves the tracking results. In conclusion, the proposed weights are able to reduce the influence of artifacts, resulting in a more accurate quantitative analysis

Left Ventricular Border Tracking Using Cardiac Motion Models and Optical Flow

The use of automated methods is becoming increasingly important for assessing cardiac function quantitatively and objectively. In this study, we propose a method for tracking three-dimensional (3-D) left ventricular contours. The method consists of a local optical flow tracker and a global tracker, which uses a statistical model of cardiac motion in an optical-flow formulation. We propose a combination of local and global trackers using gradient-based weights. The algorithm was tested on 35 echocardiographic sequences, with good results (surface error: 1.35 ± 0.46 mm, absolute volume error: 5.4 ± 4.8 mL). This demonstrates the method’s potential in automated tracking in clinical quality echocardiograms, facilitating the quantitative and objective assessment of cardiac functio

Parasternal versus apical view in cardiac natural mechanical wave speed measurements

Shear wave speed measurements can potentially be used to noninvasively measure myocardial stiffness to assess the myocardial function. Several studies showed the feasibility of tracking naturalmechanical waves induced by aortic valve closure in the interventricular septum, but different echocardiographic views have been used. This article systematically studied the wave propagation speedsmeasured in a parasternal long-axis and in an apical four-chamber view in ten healthy volunteers. The apical and parasternal views are predominantly sensitive to longitudinal or transversal tissue motion, respectively, and could, therefore, theoreticallymeasure the speed of different wave modes. We found higher propagation speeds in apical than in the parasternal view (median of 5.1 m/s versus 3.8 m/s, p < 0.01, n = 9). The results in the different views were not correlated (r = 0.26, p = 0.49) and an unexpectedly large variability among healthy volunteers was found in apical view compared with the parasternal view (3.5-8.7 versus 3.2-4.3 m/s, respectively). Complementary finite element simulations of Lamb waves in an elastic plate showed that different propagation speeds can be measured for different particlemotion componentswhen differentwavemodes are induced simultaneously. The in vivo results cannot be fully explained with the theory of Lamb wave modes. Nonetheless, the results suggest that the parasternal long-axis view is amore suitable candidate for clinical diagnosis due to the lower variability in wave speeds

Particle Acceleration in Cosmic Sites - Astrophysics Issues in our Understanding of Cosmic Rays

Laboratory experiments to explore plasma conditions and stimulated particle acceleration can illuminate aspects of the cosmic particle acceleration process. Here we discuss the cosmic-ray candidate source object variety, and what has been learned about their particle-acceleration characteristics. We identify open issues as discussed among astrophysicists. -- The cosmic ray differential intensity spectrum is a rather smooth power-law spectrum, with two kinks at the "knee" (~10^15 eV) and at the "ankle" (~3 10^18 eV). It is unclear if these kinks are related to boundaries between different dominating sources, or rather related to characteristics of cosmic-ray propagation. We believe that Galactic sources dominate up to 10^17 eV or even above, and the extragalactic origin of cosmic rays at highest energies merges rather smoothly with Galactic contributions throughout the 10^15--10^18 eV range. Pulsars and supernova remnants are among the prime candidates for Galactic cosmic-ray production, while nuclei of active galaxies are considered best candidates to produce ultrahigh-energy cosmic rays of extragalactic origin. Acceleration processes are related to shocks from violent ejections of matter from energetic sources such as supernova explosions or matter accretion onto black holes. Details of such acceleration are difficult, as relativistic particles modify the structure of the shock, and simple approximations or perturbation calculations are unsatisfactory. This is where laboratory plasma experiments are expected to contribute, to enlighten the non-linear processes which occur under such conditions.Comment: accepted for publication in EPJD, topical issue on Fundamental physics and ultra-high laser fields. From review talk at "Extreme Light Infrastructure" workshop, Sep 2008. Version-2 May 2009: adjust some wordings and references at EPJD proofs stag

Central venous catheter–associated complications in pediatric patients diagnosed with Hodgkin lymphoma: implications for catheter choice

Purpose The purpose of this study was to determine the most optimal central venous catheter (CVC) for pediatric patients with Hodgkin lymphoma (HL) in terms of complications.Methods A retrospective study including patients diagnosed with HL from 2015 to 2021 at the Princess Maxima Center was performed. Patients were followed from CVC insertion until removal or 06-2021, whichever came first. The primary outcome was the CVC-related complication incidence rate (IR) per 1000 CVC-days. Furthermore, the incidence rate ratio (IRR) was calculated by comparing complication IRs between peripherally inserted central catheters (PICC) and totally implantable venous access ports (TIVAP). Additionally, risk factors for central venous thrombosis (CVT) were identified.Results A total of 98 patients were included. The most frequently observed complications were local irritation/infections (18%; IR 0.93), malfunctions (15%; IR 0.88), and CVC-related CVTs (10%; IR 0.52). Single lumen PICCs were associated with a higher risk of complications (49% vs. 26%; IRR 5.12, CI95% 2.76-9.50), severe complications (19% vs. 7%; IRR 11.96, CI95% 2.68-53.42), and early removal (18% vs. 7%; IRR 9.96, CI95% 2.18-45.47). A single lumen PICC was identified as a risk factor for CVC-related CVT when compared to TIVAPs (12% vs. 7%, IRR 6.98, CI95% 1.45-33.57).Conclusion The insertion of a TIVAP rather than a PICC should be recommended for pediatric patients with HL, especially in the presence of CVT-related risk factors. Future trials should evaluate the efficacy and safety of direct oral anticoagulants for the primary prevention of CVT in pediatric patients with a PICC and other CVT-related risk factors.Analysis and Stochastic

Measuring the depth of invasion in vulvar squamous cell carcinoma: interobserver agreement and pitfalls

Aims: The depth of invasion is an important prognostic factor for patients with vulvar squamous cell carcinoma (SCC). The threshold of 1 mm distinguishes between FIGO stages IA and ≥IB disease and guides the need for groin surgery. Therefore, high interobserver agreement is crucial. The conventional and the alternative method are described to measure the depth of invasion. The aims of this study were to assess interobserver agreement for classifying the depth of invasion using both methods and to identify pitfalls. Methods and results: Fifty slides of vulvar SCC with a depth of invasion approximately 1 mm were selected, digitally scanned and independently assessed by 10 pathologists working in a referral or oncology centre and four pathologists in training. The depth of invasion was measured using both the conventional and alternative method in each slide and categorised into ≤1 and >1 mm. The percentage of agreement and Light’s kappa for multi-rater agreement were calculated, and 95% confidence intervals were calculated by bootstrapping (1000 runs). The agreement using the conventional method was moderate (κ = 0.57, 95% confidence interval = 0.45–0.68). The percentage of agreement among the participating pathologists using the conventional method was 85.0% versus 89.4% using the alternative method. Six pitfalls were identified: disagreement concerning which invasive nest is deepest, recognition of invasive growth and where it starts, curved surface, carcinoma situated on the edge of the tis

Le projet de loi du droit du mariage en République fédéral d'Allemagne

Bosch F.W. Le projet de loi du droit du mariage en République fédéral d'Allemagne. In: Revue internationale de droit comparé. Vol. 24 N°1, Janvier-mars 1972. pp. 55-75