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Comparing Levovist-enhanced pulse inversion harmonic imaging and ferumoxides-enhanced MR imaging of hepatic metastases
No full textOBJECTIVE
.
The aim of this study was to compare the sensitivity of pulse inversion harmonic
digital sonography, unenhanced transabdominal sonography, and ferumoxides-enhanced
MR imaging in the depiction of liver metastases. In addition, pulse inversion
harmonic digital sonography was performed at different scanning times after Levovist injection
to define the best phase for depiction.
SUBJECTS AND METHODS.
Twenty-six consecutive patients with findings of extrahepatic
primary malignancies and liver metastases suspected on transabdominal sonography
were examined with both pulse inversion harmonic imaging and ferumoxides-enhanced MR
imaging within a 7-day period. Pulse inversion harmonic imaging was performed before and
at 20, 100, and 180 sec after a bolus injection of Levovist. MR imaging was performed before
and after ferumoxides administration, using breath-hold gradient-recalled echo T1-weighted
and turbo spin-echo short tau inversion recovery T2-weighted sequences. Two radiologists independently
evaluated image quality, and the number, location, and diameter of lesions
scanned using both techniques. Intraoperative sonography or at least 8-month follow-up confirmed
the lesions depicted. Analyses included Wilcoxon’s signed rank test and Interclass correlation
test.
RESULTS.
Levovist-enhanced pulse inversion harmonic imaging revealed 104 metastases
on the first scan after contrast injection, 126 on the second scan, and 118 on the third, compared
with 66 on the unenhanced scan. Pulse inversion harmonic digital sonography depicted
90% of lesions shown on ferumoxides-enhanced MR imaging (140 metastases) (
p
= 0.001).
CONCLUSION.
Levovist-enhanced pulse inversion harmonic digital sonography is a
sensitive technique for depiction of liver metastases. Pulse inversion harmonic digital sonography
may have a potential role in imaging patients with possible metastatic involvement of
the liver. Further studies are needed to define its place in the workup of these patients. At
present, ferumoxides-enhanced MR imaging, being more sensitive, must be performed in all
patients in whom pulse inversion harmonic digital sonography is not conclusive or when after
pulse inversion harmonic digital sonography, patients remain eligible for surgery
Does multidetector-row CT eliminate the role of diagnostic laparoscopy in assessing the resectability of pancreatic head adenocarcinoma?
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
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