1,720,979 research outputs found
Le nuove sequenze quantitative in risonanza magnetica cardiaca per lo studio delle malattie del miocardio in pazienti con extrasistoli ventricolari.
Full text linkLa Risonanza Magnetica Cardiaca (RMC) è considerata uno dei più completi strumenti diagnostici in ambito cardiovascolare, è una metodica multiplanare, ha un’elevata risoluzione spaziale, temporale e di contrasto, consentendo la valutazione non solo morfo-funzionale delle camere cardiache ma ci permette anche di caratterizzare il tessuto miocardico. Durante un periodo di svariati decenni, la Cardio-RM si è evoluta fornendoci immagini sempre più raffinate che permettono di valutare globalmente l’apparato cardiovascolare, con ottimi risultati in termini di sensibilità e specificità. Inoltre, grazie all’ampia disponibilità di dati raccolti, il suo ruolo non si esaurisce nella diagnosi, ma risulta fondamentale anche nella valutazione prognostica dei principali quadri patologici.
Di recente introduzione risultano le sequenze per lo studio del Mapping.
L’innovazione rispetto all’utilizzo delle sequenze tradizionali è data dalla capacità di misurare il valore assoluto dei tempi di rilassamento T1 e T2 consentendo una valutazione quantitativa, e non più solo qualitativa, delle immagini RM. Con tali sequenze è possibile visualizzare e parametrare aree di edema, necrosi e fibrosi miocardica senza l’utilizzo del mezzo di contrasto. Inoltre, l’analisi del T1 Mapping prima e dopo la somministrazione ev del mezzo di contrasto paramagnetico, consente la stima del Volume Extracellulare, parametro che correla bene con l’aumento dello spazio extracellulare in svariate patologie cardiache.
L’obiettivo di questo lavoro è dimostrare le potenzialità delle metodiche di Mapping comparate con l’LGE che rappresenta il gold standard nella valutazione della necrosi/fibrosi miocardica nel rilevare patologie cardiache misconosciute in pazienti con extrasistolia ventricolare e cuore sano alle metodiche di imaging di I livello
Cardiac magnetic resonance imaging for the diagnosis and follow-up of Loeffler's endocarditis
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
Magnetic resonance mapping for the assessment of cardiomyopathies and myocardial disease
No full text: In recent years, the use of cardiac magnetic resonance (CMR) has grown exponentially in clinical practice. The keys for this success are represented by the possibility of tissue characterization, cardiac volumes and myocardial perfusion assessment, biventricular function evaluation, with no use of ionizing radiations and with an extremely interesting profile of reproducibility. The use of late gadolinium enhancement (LGE) nearly compares a non-invasive biopsy for cardiac fibrosis quantification. LGE, however, is partly unable to detect diffuse myocardial disease. These limits are overcome by new acquisition techniques, mainly T1 and T2 mapping, which allow the diagnosis and characterization of various cardiomyopathies, both ischemic and non-ischemic, such as amyloidosis (high T1), Fabry's disease (low T1), hemochromatosis (low T1), dilated and hypertrophic cardiomyopathy and myocarditis. In this review we detail and summarize principal evidence on the use of T1 and T2 mapping for the study and clinical management of cardiomyopathies
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
- …
