1,720,972 research outputs found
Bayesian Quantification of Contrast-Enhanced Ultrasound Images with Adaptive Inclusion of an Irreversible Component
No full textContrast Enhanced Ultrasound (CEUS) is a sensitive imaging technique to assess tissue vascularity and it can be particularly useful in early detection and grading of arthritis. In a recent study we have shown that a Gamma-variate can accurately quantify synovial perfusion and it is flexible enough to describe many heterogeneous patterns. However, in some cases the heterogeneity of the kinetics can be such that even the Gamma model does not properly describe the curve, with a high number of outliers
Pixel-based approach to assess contrast-enhanced ultrasound kinetics parameters for differential diagnosis of rheumatoid arthritis
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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
Dynamic Automated Synovial Imaging (DASI) for Differentiating between Rheumatoid Arthritis and Simil-Rheumatoid Psoriatic Arthritis
No full textVariations 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
Dynamic Automated Synovial Imaging (DASI) For Differentiating Between Rheumatoid Arthritis And Other Forms Of Arthritis: Automated Versus Manual Interpretation In Contrast-Enhanced Ultrasound
No full textBackground: Rheumatoid arthritis (RA) is the most aggressive chronic arthritis and affects about 1% of population, impacting severely both the individual wellbeing and the health care system. Early diagnosis and effective treatment can avoid the devastating outcome of RA1, but the differential diagnosis is especially difficult at its onset. The diagnosis relies on conventional methods (clinical parameters, autoantibodies), even if distinct vascularization patterns have been identified in biopsy specimens2. Contrast-enhanced ultrasound (CEUS) allows a non-invasive dynamic study of synovial vascularisation and perfusion, although its capacity in differentiating among different arthritis forms has not yet been evaluated3,4.
Objectives: to investigate the performance of quantitative analysis of CEUS data versus manual semiquantitative assessment in differentiating RA from other arthritis (non-RA).
Methods: 78 outclinic patients with finger joints arthritis were recruited, 33 with RA and 45 with other arthritis. The most active joint was chosen for CEUS examination as previously described3, using a US device (MyLab25, Esaote) equipped with Contrast tuned Imaging (CnTI, Esaote), and as contrast agent sulfur hexafluoride microbubbles (SonoVue; Bracco International). Both the anatomical B-mode image and the CnTI cineloop video were digitally stored for subsequent quantiative analysis or manual review. Two in arthritis experienced radiologists manually assessed the examinations as consistent with RA or not. Quantitative image analysis was performed firstly applying a semi-automatic detection of synovial boundaries5. Then, the contrast time-activity curve of all pixels belonging to the synovial and perisynovial region was analysed fitting a gamma curve f(t)=A(t-t0)a×e(t-t0)/b on the data. The statistics summarizing the distribution of the estimated kinetics parameters in the synovial and in the perisynovial tissue were computed and their difference between the two groups (RA and non-RA) analyzed, so to study the existance of different vascularization or flow patterns. Finally, a supervised classifier (random forest) was trained to classify each patient through its CEUS-derived parameters, validating the classifier diagnostic power using a leave-one-out strategy.
Results: Manual assessment of CEUS examination consistent with RA or non-RA performed by radiologists showed high sensitivity (0,9), but indeed low specificity and accuracy (0,46 and 0,69, respectively). On the contrary, the classifier using CEUS quantitative parameters showed both good sensitivity (0,88) and specificitity (0,94), resulting in a diagnostic accuracy of 0,92.
Conclusions: The Dynamic Automated Synovial Imaging (DASI) proposed provided a high accuracy in discriminating RA from non-RA arthritis. DASI promises to be a powerful tool for the diagnosis and follow-up of arthritis, attributing to CEUS a new role in the field
AB0953 A Comparison of Region-Based and Pixel-Based CEUS Kinetics Parameters in the Differentiation of Rheumatoid Arthritis and Simil-Rheumatoid Psoriatic Arthritis
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