1,720,962 research outputs found
Non-invasive assessment of coronary artery bypass graft with retrospectively ECG-gated four-row multi-detector spiral computed tomography
No full textThe purpose of this study was to assess the accuracy of four- row multi-detector CT (MDCT) in the evaluation of coronary artery by- pass graft (CABG) in patients with at least a left internal mammary artery (LIMA) grafted to the left anterior descending artery (LAD), because of the conduit of choice in bypass surgery and the greater diffi- culty of evaluation with non-inva- sive diagnostic tools. Included in
the study were 57 patients with a total of 122 grafts (95 arterial and 27 venous) who underwent MDCT (4×2.5-mm detector-collimation, 3-mm slice width, 1.5-mm recon- struction increment) with retrospec- tive ECG gating. Twelve patients (21%) with high heart rates were given beta-blockers in order to ob- tain a heart rate ≤70 bpm in all pa- tients. The ECG-synchronized axial images, reconstructed in the mid- diastole, MPR, MIP and 3D-VR images were independently and blindly assessed by two radiologists for graft patency and presence of high grade stenosis. Conventional angiography was the standard of reference. MDCT correctly classified 92/94 patent grafts and 26/28 oc- cluded grafts (sensitivity/specificity 93%/97.8%); sensitivity and speci- ficity of MDCT for assessment of arterial grafts were 100 and 98.7% (77/78 patent grafts and 17/17 oc- cluded grafts). Image quality was considered adequate for assessment
of significant stenoses in 62/92 (67%) patent grafts, with a signifi- cant differences between LIMA and non-LIMA conduits (44/57 vs. 18/65; P=0.002), according to the coronary vessel area supplied (anterior>lateral>posterior-inferior wall; P=0.002). In the remaining 30 patent grafts (33%), the assessment of stenoses was hampered by surgi- cal clips, calcifications and motion artifacts. Sensitivity and specificity of MDCT for detection of significant graft stenoses were 80 and 96%, re- spectively. Inter-observer agreement was good (K=0.73). MDCT seems to be a valuable diagnostic tool for non-invasive assessment of patency of both venous and arterial grafts. An accurate evaluation of distal anastomoses and native coronary arteries may still represent a limita- tion of four-row MDCT, which will improve with the newest MDCT scanner
Late coronary thrombosis after drug-eluting stent: stent vs patient-driven prescription of aspirin-clopidogrel combination
No full textA pictorial review of coronary artery bypass grafts at multidetector row CT
No full textMultidetector row CT scanners with submillimeter spatial resolution and high temporal resolution are now available and are increasingly used for noninvasive assessment of vascular disease including coronary arteries and grafts. The entire heart and graft course can be scanned within a single breath-hold, and contrast-enhanced images are reconstructed through retrospective ECG gating. In this pictorial review, we describe the CT findings of the most commonly used coronary artery bypass grafts on both axial images and two-dimensional and three-dimensional images providing a correlation with conventional coronary angiography
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
An early decline of collateral circulation parallels myocardial ischaemia during percutaneous coronary intervention: a drawback of recanalization of chronic coronary occlusions?
No full textDispelling 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
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