Search results for "Contrast"

Ergebnisse der kontrastverstärkten MR-Angiographie der aortoiliakalen Gefäße mit einem 1-molaren Kontrastmittel bei 1,0 T: Vergleich zur i. a. DSA

2004

PURPOSE To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) using a 1.0 molar contrast agent at 1.0 T for the diagnosis of abdominal aortic aneurysms and stenoses of renal or iliac arteries in comparison to intraarterial digital subtraction angiography (DSA). MATERIALS AND METHODS A total of 19 patients with the suspicion of abdominal aortic aneurysm or stenosis of renal or iliac arteries were examined with CE-MRA at 1.0 T. Intra-arterial DSA served as reference in all cases. After test bolus tracking, 10 or 8 ml of the 1.0 molar contrast agent Gadobutrol corresponding to a dose of 0.1 - 0.15 mmol/kg bw were injected and imaging performed using a FLASH-3D sequen…

Gadolinium-chelating nanogels as MR contrast agents specifically targeting tumor cells

2014

Aims and objectives Methods and materials Results Conclusion Personal information References

Isolation of the left atrial surface from cardiac multi-detector CT images based on marker controlled watershed segmentation

2006

The delineation of left atrium (LA) and pulmonary veins (PVs) anatomy from high resolution images holds importance for atrial fibrillation (AF) investigation and treatment. In this study, a semiautomatic segmentation procedure for LA and PVs inner surface from contrast enhanced CT data was developed. The procedure consists of a three dimensional marker controlled watershed segmentation applied to the external morphological gradient, followed by variable threshold surface extraction from the original intensity image. A preliminary anisotropic non-linear filtering was implemented to improve the S/N ratio of CT images. The performance of segmentation was evaluated on cardiac CT scans of 12 AF …

Visual Acuity in Myopes with Standard and Reversed Contrast Optotypes

2017

Abstract The aim of this study was to assess the visual acuity of myopes with standard and reversed contrast optotypes and to determine how the visual acuity of myopes is affected by optical defocus and the type of optical correction, either contact lenses or spectacles. Twenty-three myopic subjects (18 and 23 years old) with uncorrected vision had their visual acuity assessed with both standard and reversed contrast optotypes. The study also included 10 myopes with contact lens as well as habitual spectacle correction. The visual acuity for myopes with uncorrected vision was better with reversed than standard contrast optotypes. Better reversed contrast than standard contrast visual acuity…

IOL Multifocali di II e III generazione: performance visiva e capacità di lettura

2011

Predictability and prediction of lowest observed adverse effect levels in a structurally heterogeneous set of chemicals

2005

A database of chronic lowest observed adverse effect levels (LOAELs) for 234 compounds, previously compiled from different sources (Toxicology Letters79, 131-143 (1995)), was modelled using graph theoretical descriptors. This study reveals that data are not homogeneous. Only those data originating from the U.S. Environmental Protection Agency (EPA) reports could be well modelled by multilinear regression (MLR) and linear discriminant analysis (LDA). In contrast, data available from the specific procedures of the National Toxicology Program (NTP) database introduced noise and did not render good models either alone, or in combination with the EPA data.

Looking Across Instead of Back and Forth: How the Simultaneous Presentation of Multiple Animation Episodes Facilitates Learning

2017

Many learning tasks require students to induce higher-order relationships from the learning material. Compare and contrast processes play a pivotal role in solving such inductive tasks. Different presentations of animation episodes offer affordances to students that can either impede or facilitate compare and contrast processes. While conventional behaviorally realistic animations typically present multiple episodes one after the other, i.e. sequentially, simultaneous presentation offers a feasible alternative. We investigated how the sequential and simultaneous presentation of multiple animation episodes affects students’ perceptual interrogation of the animation as well as their learning …

Assessment of the statistical significance of classifications in infrared spectroscopy based diagnostic models.

2014

Fourier transform infrared (IR) spectroscopy in combination with multivariate data analysis is a versatile tool that can be applied to disease diagnosis. However, a rigorous validation of the obtained models is necessary in order to obtain robust results. This work evaluates the advantages of the use of permutation testing for determining the statistical significance of the misclassification errors obtained from IR based diagnostic models through cross validation (CV). The model performance, estimated by CV, is compared to a distribution of CV-performance values obtained using randomly permuted class labels. The distribution of ‘random CV-values’ is considered as a null distribution and use…

Discordance between two national health statistics sources (EMH and EESCRI, 1990–2009). Analysis of psychiatric morbidity

2013

Abstract Introduction Two statistical sources provide data on hospital stays and discharges for all Spanish hospitals: Hospital Morbidity Survey (acronym in Spanish: EMH) and Statistics of Health Establishments providing Inpatient Care (acronym in Spanish: EESCRI). Our aim is to contrast these two statistical sources to define their accuracy and relevance in psychiatric epidemiology studies. Material and methodology The analysis is based on two aspects: (1) Compare the number of psychiatric stays and hospital discharges from 1990 to 2009. (2) Analyse and compare how the average stay is provided. Results The differences between the two statistical sources are significant and increase over ti…

1993

From his studies on Invertebrate animals and fossils in the vicinity of Paris, J.-B. de Lamarck (1744–1829) formulated a number of conclusions in his Zoological Philosophy [1] (1809), the first coherent theory of evolution. However, in contrast to commonly held belief, this was not based purely on speculation, but was progressively elaborated.