1,720,972 research outputs found
Automated Detection of Pulmonary Nodules from Multi-slice CT Images of Varying Slice Thickness and Reconstruction Interval
No full textAutomated detection of pulmonary nodules on CT images: Effect of section thickness and reconstruction interval - Initial results
No full textInstitutional review board approval was obtained. Informed patient consent was not required. Study was compliant with HIPAA. Performance of an automated pulmonary nodule detection program was evaluated on multi-detector row CT images that were acquired once but reconstructed retrospectively at different section thicknesses and reconstruction intervals. From raw CT data in 10 patients with pulmonary nodules, three sets of CT images were reconstructed separately in each patient by selecting two section thickness and reconstruction combinations, respectively: thin group, 1 and 1 mm; overlap group, 5 and 1 mm; and thick group, 5 and 5 mm. Nodules 3 mm in diameter and larger were detected in each group (thin group, 126 nodules; overlap group, 121 nodules, and thick group, 114 nodules) by means of consensus of two radiologists. Findings were used as the reference standard for evaluation of the computer-aided detection (CAD) program. Sensitivity and number of false-positive findings per patient by CAD were: thin group, 95.2% (120 of 126 nodules) and 5.4 findings; overlap group, 94.2% (114 of 121 nodules) and 9.7 findings; and thick group, 88.6% (101 of 114 nodules) and 23.6 findings, indicating that nodule detection degraded with increase in section thickness but improved substantially with a small reconstruction interval. ((c)) RSNA, 2005.
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
Focal liver lesions hyperintense on T1-weighted magnetic resonance images.
No full textThis article reviews focal liver lesions hyperintense on T1-weighted magnetic resonance (MR) images and describes the underlying etiologies associated with their T1 signal intensity. Although focal liver lesions are commonly detected because of their iso- or hypointensity on T1-weighted images, lesions (benign or malignant) may present with T1 hyperintensity when they contain T1 shortening elements--such as fat, hemorrhage, copper, melanin, and highly concentrated proteins. Our discussion includes the description of state-of-the-art T1-weighted MR sequences and the imaging features of lesions on pre- and postcontrast MR images that are characteristic for lesion composition and useful for making accurate diagnosis
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
Differential Renal Function Estimation Using Computerized Tomography Based Renal Parenchymal Volume Measurement
No full textPurpose: Nuclear renal scan is currently the gold standard imaging study to determine differential renal function. We propose helical computerized tomography as a more efficient way to gain renal function information. Renal parenchymal volume is measured and percent total renal volume is used as a surrogate marker for differential renal function. Materials and Methods: Computerized tomography and diuretic enhanced nuclear renal scan were performed in 33 patients with chronic obstruction. Computerized tomography was contrast enhanced in 23 cases and nonenhanced in 10. Diagnoses included ureteropelvic junction obstruction, ureteral stricture and extrinsic compression. Using semiautomated boundary delineation with manual editing method the parenchymal volume of each kidney was measured and percent renal volume was calculated. Percent renal volume was compared with percent renal function, as determined by nuclear renal scan. Correlations between the 2 measures were evaluated using the Spearman or Pearson coefficient. Results: Strong correlations were observed between percent renal function and percent renal volume in all cases (r = 0.90, p < 0.001), including the enhanced (r = 0.87, p < 0.001) and nonenhanced (r = 0.95, p < 0.001) groups. Moderately strong correlations were noted in the less than 40% (r = 0.76, p < 0.001) and less than 30% (r = 0.64, p = 0.015) renal function subgroups. Conclusions: Differential renal volume measured from computerized tomography strongly correlates with differential renal function on nuclear renal scan for normal and chronically obstructed kidneys. Computerized tomography may serve as a single radiological diagnostic study for anatomical and functional assessment in patients in whom a poorly functioning kidney is suspected
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