1,721,045 research outputs found
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
Quantitative magnetic resonance imaging for focal liver lesions: Bridging the gap between research and clinical practice
Full text linkMagnetic resonance imaging (MRI) is highly important for the detection, characterization, and follow-up of focal liver lesions. Several quantitative MRI-based methods have been proposed in addition to qualitative imaging interpretation to improve the diagnostic work-up and prognostics in patients with focal liver lesions. This includes DWI with apparent diffusion coefficient measurements, intravoxel incoherent motion, perfusion imaging, MR elastography, and radiomics. Multiple research studies have reported promising results with quantitative MRI methods in various clinical settings. Nevertheless, applications in everyday clinical practice are limited. This review describes the basic principles of quantitative MRI-based techniques and discusses the main current applications and limitations for the assessment of focal liver lesions
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
Immunotherapy-Based Treatments of Hepatocellular Carcinoma: AJR Expert Panel Narrative Review
No full textThe advent of immunotherapy for patients with hepatocellular carcinoma (HCC) has changed the treatment landscape and conferred a survival benefit on patients with advanced HCC, who typically have a very poor prognosis. The most pronounced improvements in response, as documented by standardized response criteria based on CT or MRI, have been achieved when immunotherapy is combined with other systemic or locoregional therapies. Immune checkpoint inhibitor treatments result in unique patterns on CT and MRI that challenge the application of conventional response criteria such as RECIST, modified RECIST, and European Association for the Study of the Liver criteria. Thus, newer criteria have been developed to gauge therapy response or disease progression for patients receiving immunotherapy, including immune-related RECIST (iRECIST) and immune-modified RECIST (imRECIST), though these remain unvalidated. In this review, we describe the current landscape of immunotherapeutic agents used for HCC, summarize the results of published studies, review the pathobiologic mechanisms that provide a rationale for the use of these agents, and report on the status of response assessment for immunotherapy either alone or in combination with other treatment options. Finally, consensus statements are provided to inform radiologists about essential considerations in the era of a rapidly changing treatment paradigm for patients with HCC
Evaluation of washout using subtraction MRI for the diagnosis of hepatocellular carcinoma in cirrhotic patients with spontaneously T1-hyperintense nodules
No full textPurpose: The purpose of this study was to assess the value of subtraction imaging on post-arterial phase images (i.e., portal venous, delayed/transitional and hepatobiliary phases) for the non-invasive diagnosis of hepatocellular carcinoma (HCC) in spontaneously hyperintense nodules on T1-weighted imaging in patients with cirrhosis. Materials and methods: Forty-five patients with a total 55 hepatic nodules that were spontaneously hyperintense on T1-weighted images were initially retrieved. All patients underwent MRI examination of the liver using extracellular agent. Each nodule was assessed for sensitivity and specificity using LI-RADS (Liver Imaging Reporting and Data System) during two reading sessions performed first without then with subtraction images on post-arterial phase images. The final standard of reference was defined by a step-by-step algorithm previously published combining histology, typical imaging, alfa fetoprotein and follow-up. Results: Forty-six nodules (26 HCC) in 39 patients with cirrhosis were analyzed. Using LI-RADS, the sensitivity and specificity for the diagnosis of HCC were 64% (95% CI: 41-83) and 67% (95% CI: 41-87) without subtraction; and 73% (95% CI: 50-89) (P > 0.999) and 33% (95% CI: 13-59) (P = 0.553) on subtraction imaging using extracellular contrast agent. Fifty-five percent (22/40) of nodules displayed a washout without subtraction and 70% (28/40) did so on subtraction imaging obtained with extracellular contrast agent. Twenty nodules out of 40 (50%) were classified LI-RADS 5 without subtraction, and 28 out of 40 nodules (70%) with subtraction. Conclusion: The results of this study suggest that the use of subtraction imaging on post-arterial phase images (i.e., PVP, DP/TP and HBP) is not relevant for the non-invasive diagnosis of HCC for spontaneously hyperintense nodules on T1-weighted images in patients with liver cirrhosis
Hepatocellular Carcinoma: Optimal Radiological Evaluation before Liver Transplantation
Full text linkLiver transplantation (LT) is the recommended curative-intent treatment for patients with
early or intermediate-stage hepatocellular carcinoma (HCC) who are ineligible for resection. Imaging
plays a central role in staging and for selecting the best LT candidates. This review will discuss recent
developments in pre-LT imaging assessment, in particular LT eligibility criteria on imaging, the
technical requirements and the diagnostic performance of imaging for the pre-LT diagnosis of HCC
including the recent Liver Imaging Reporting and Data System (LI-RADS) criteria, the evaluation of
the response to locoregional therapy, as well as the non-invasive prediction of HCC aggressiveness
and its impact on the outcome of LT. We will also briefly discuss the role of nuclear medicine in the
pre-LT evaluation and the emerging role of artificial intelligence models in patients with HCC
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