1,721,148 research outputs found
NOVEL ANGIOGRAPHIC TECHNIQUES FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE AND FOR ASSESSMENT OF ITS PERCUTANEOUS TREATMENT
No full textNACoronary angiography is considered the standard for coronary anatomy definition. The utility of coronary angiography is dependent on its ability to identify the structure of the coronary vascular bed and the presence of obstructive disease. However, radiographic imaging of the coronary tree depicts the arteries as simple 2-dimensional projections of the lumen and this "luminogram" is a poor representation of the real coronary anatomy. The combination of foreshortening, tortuosity, overlap, and anatomic variation may result in insufficient description of the real coronary anatomy. Rotational and 3-dimensional techniques have been developed to minimize the imaging limitations of 2-dimensional angiography. Rotational angiography is a technique that provides, with one single contrast injection, a dynamic cine-angiogram of the coronary tree, during a rotation of the gantry around the thorax of the patient. This single rotational acquisition of the coronary tree, matched with the electrocardiographic recording of the patient, permits the automatic selection, of 2 different views of the coronary segment of interest in the same phase of the cardiac cycle. These views are used to reconstruct a 3-dimesnional model, which allows automatic “auto-calibrated” measurements of the coronary arteries. Rotational angiography and 3-dimensional modeling are compared with standard 2-dimensional techniques in the first part of this thesis. Rotational angiography provides similar image quality as conventional 2-dimensional angiography, while 3-dimensional modeling has the potential to provide more accurate information than standard 2-dimensional angiography, mainly in terms of adequacy of length assessment. Indeed, 3-dimensional modeling provides coronary segment lengths closer to the actual real length, while 2-dimensional angiography tends to underestimate the real length of the coronary arteries.
In addition, in case the coronary anatomy allows percutaneous treatment of the stenoses, stent implantation is considered the optimal management to achieve successful dilatation of these lesions. However, adequate evaluation of the stenting procedure by means of simple angiography is insufficient to determine the quality of the intervention itself, in terms of good expansion of the stent and good apposition of the device to the vessel wall. A novel simple angiographic technique, StentBoost, based on the angiographic enhancement of the intravascular prosthesis deployed, has been recently developed to overcome limitations of standard angiography. Examples of the angiographic result after stent implantation with StentBoost applied to conventional and new percutaneous coronary techniques are shown in the second part of this thesis. StentBoost allows for optimization of the coronary procedure in complex anatomies, such as: 1) percutaneous stenting of a bifurcation lesion with the conventional single stent plus kissing balloon technique, 2) percutaneous treatment of a bifurcation lesion using the novel self expanding conus-shaped biolimus-eluting nitinol Axxess stent, 3) percutaneous treatment of a small vessel with the novel self-expanding sirolimus-eluting nitinol Sparrow stent-in-wire, and 4) percutaneous stenting of a bifurcation lesion with the novel self-expanding bare nitinol Stentys stent system for enhanced provisional bifurcation stenting
Meta-analytic rage or race for evidence-based interventional cardiology?
No full text[No abstract available
Interosseous artery collaterals and their support to ulno-palmar arch: A case report and a review of the literature
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
