1,721,067 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
Study of quantitative imaging methods for the non-invasive assessment of cirrhosis, portal hypertension and tumour characterisation
No full textCe travail de thèse explore deux thèmes : 1) la quantification non invasive de l'hypertension portale chez le patient avec cirrhose, en utilisant une nouvelle méthode : la quantification de la nodularité de la surface hépatique (Liver Surface Nodularity ' LSN), soit par scanner que par IRM ; 2) l'évaluation de deux nouvelles outils de segmentation et caractérisation des nodules hépatiques au scanner, basés sur les reconstructions d'apprentissage profonde. Nous avons démontré l'efficacité de la LSN en tant que marqueur non invasif pour l'identification des patients ayant une hypertension portale cliniquement significative, dans différents scénarios cliniques, avec des populations de patients opérés pour un CHC ou avec une transplantation hépatique, permettant une évaluation par rapport au standard de référence représenté par la mesure du gradient de pression (HVPG). En plus, nous avons démontré une performance diagnostique comparable entre la LSN et la mesure de l'élasticité du foie (LSM-TE) et le score combiné LSPS (LSM * rapport taille de la rate / nombre plaquettes), résultant en un AUROC de : 0.87±0.31 ; 0.87±0.04 et 0.85 ± 0.04, respectivement, sans différence significative de la performance diagnostique (DeLong, p=0.28 ; 0.37 ; et 0.65, respectivement). En raison de la rareté des études sur la LSN dans la littérature, nous avons mené une étude visant à définir les critères de qualité pour la mesure de la LSN, en démontrant rigoureusement la meilleure combinaison du nombre de mesures par patient, en maximisant la précision et en minimisant la variabilité. Enfin, nous avons montré que LSN est également réalisable sur des images IRM, avec une précision diagnostique similaire au scanner et une variabilité inter- et intra-opérateur comparable. Ce résultat a permis d'analyser les performances de la LSN sur des images IRM pour l'identification de la fibrose hépatique avancée chez les patients atteints de NASH, notamment après intégration avec le score FIB-4, avec une classification correcte de 73% des patients de la cour d'étude. Enfin, la polyvalence de la LSN a été démontrée dans une étude menée en collaboration avec le département d'hépatologie, dans laquelle la séméiologie scannographique classique a été comparée au biomarqueur quantitatif LSN, pour différencier les patients atteints de cirrhose de ceux présentant une maladie vasculaire porto-sinusoïdale, avec signes d'hypertension portale comparables. La combinaison des signes classiques et de la LSN a permis d'obtenir une précision diagnostique de 84% pour la différentiation des deux pathologies. Pour le deuxième thème de la thèse, nous avons participé à une étude visant à comparer les performances d'un algorithme basé sur l'apprentissage automatique dans l'évaluation des caractéristiques majeures LI-RADS v2018 et la catégorisation des observations hépatiques au scanner par rapport à une évaluation visuelle réalisée par un panel de radiologues. Nos resultats ont démontré que l'algorithme proposé peut évaluer la hypervascularisation à la phase artérielle non-périphérique, le lavage non périphérique et la capsule se rehaussant, selon les critères LI-RADS, et catégoriser les observations du foie au scanner, ce qui pourrait aider les radiologues à normaliser leur compte rendu conformément aux dernières recommandations. Enfin, nous avons participé au développement et à la validation des performances diagnostiques d'un algorithme d'apprentissage profond pour la détection automatique des lésions hépatiques secondaires chez les patients atteints de cancer colorectal, démontrant que l'algorithme possède une précision diagnostique comparable à la lecture humaine, indépendamment de la taille des lésions, de leur localisation et de la présence d'une chimiothérapie avant l'examen scannographique analysé.This thesis explores two themes: 1) the non-invasive quantification of portal hypertension in patients with cirrhosis, using a new method: the quantification of Liver Surface Nodularity (LSN), either by CT or by MRI; 2) the evaluation of two new tools for the detection and characterisation of liver nodules on CT, based on deep learning reconstructions. We have demonstrated the efficacy of LSN as a non-invasive marker for the identification of patients with clinically significant portal hypertension, in different clinical scenarios, with populations of patients undergoing surgery for HCC or with liver transplantation, allowing for an assessment compared with the reference standard represented by the pressure gradient measurement (HVPG). In addition, we demonstrated comparable diagnostic performance between the LSN and liver elasticity measurement (LSM-TE) and the combined LSPS score (LSM * spleen size/platelet count ratio), resulting in an AUROC of: 0.87±0.31; 0.87±0.04 and 0.85 ± 0.04, respectively, with no significant difference in diagnostic performance (DeLong, p=0.28; 0.37; and 0.65, respectively). Due to the paucity of studies on LSN in the literature, we conducted a study to define quality criteria for LSN measurement, rigorously demonstrating the best combination of number of measurements per patient, maximising accuracy and minimising variability. Finally, we showed that LSN can also be measured on MRI images, with a diagnostic accuracy similar to that of CT scans and comparable inter- and intra-operator variability. This result made it possible to analyse the performance of LSN on MRI images for identifying advanced liver fibrosis in patients with NASH, particularly after integration with the FIB-4 score, with correct classification of 73% of patients in the study group. Finally, the versatility of the LSN was demonstrated in a study carried out in collaboration with the Department of Hepatology, in which conventional scannographic semiology was compared with the quantitative biomarker LSN, to differentiate patients with cirrhosis from those with porto-sinusoidal vascular disease, with comparable signs of portal hypertension. The combination of the classic signs and the LSN gave a diagnostic accuracy of 84% for the differentiation of the two pathologies. For the second theme of the thesis, we took part in a study aimed at comparing the performance of a machine learning-based algorithm in the assessment of major LI-RADS v2018 features and the categorisation of liver findings on CT versus visual assessment by a panel of radiologists. Our results demonstrated that the proposed algorithm can assess hypervascularisation in the non-peripheral arterial phase, non-peripheral washout and enhancing capsule, according to the LI-RADS criteria, and categorise liver CT findings, which could help radiologists to standardise their reporting according to the latest recommendations. Finally, we participated in the development and validation of the diagnostic performance of a deep learning algorithm for the automatic detection of secondary liver lesions in patients with colorectal cancer, demonstrating that the algorithm has a diagnostic accuracy comparable to human reading, independently of lesion size, location and the presence of chemotherapy prior to the scans analysed
Bias and methodological specificities of randomized controlled trials in interventional radiology : the example of treatments for hepatocellular carcinoma
No full textLa méthodologie de l'essai contrôlé randomisé (ECR) a été utilisée pour la première fois en radiologie interventionnelle (RI) en 1985 dans un essai évaluant la chimioembolisation intraartérielle hépatique (CEH) pour le traitement du carcinome hépatocellulaire (CHC). La spécialité a progressivement adopté cette méthode d'évaluation pour les nouveaux traitements et les innovations techniques. Pourtant, l’application de cette méthodologie à la RI pose, comme pour d’autres traitements non pharmacologiques (TNP), des questions méthodologiques spécifiques liées à la complexité des interventions, à l'influence de l’opérateur, à l'expertise du centre et aux difficultés de l'aveugle, qui ont une influence majeure sur la planification, mise en œuvre et l'interprétation des ECR. Dans un premier projet, nous avons évalué dans quelle mesure les résultats des ECR enregistrés évaluant la CEH pour le traitement du CHC étaient publiquement accessibles. Parmi les 67 ECR identifiés, représentant un nombre total de 11 599 patients, près des deux tiers n'ont donné lieu à aucun résultat public, que ce soit sur la plateforme du registre ou dans une revue scientifique. La sous-déclaration des résultats des essais est une cause majeure de gaspillage de la recherche médicale, car les résultats de recherche inaccessibles n'aident ni les patients ni les cliniciens. Dans un second projet, nous avons déterminé la proportion d’ECR évaluant la CEH pour le CHC et publiés après 2007 qui étaient enregistrés. Nous avons comparé les critères de jugements principaux enregistrés avec ceux rapportés dans les publications afin de déterminer si le biais de mention favorisait les résultats significatifs. Nous avons constaté que la moitié de ces ECR publiés n'étaient pas enregistrés, et que lorsqu'ils l'étaient, un tiers d'entre eux présentaient des discordances importantes entre les critères de jugements principaux enregistrés et publiés. Un biais de mention sélectif favorisant les résultats de l'essai était observé dans 7% des ECR publiés. Dans un troisième projet, nous avons évalué l'exhaustivité du reporting des résumés dans les ECR pour la RI hépatique et l'impact de la publication de l'extension CONSORT 2017 pour le TNP. Nous avons aussi évalué la tendance d'évolution dans le temps à l'aide d'une analyse de séries chronologiques. Nous avons constaté que l'exhaustivité des rapports était faible dans les résumés d'essais pour la RI hépatique et qu’elle ne s'est pas améliorée après la publication de la déclaration CONSORT-TNP. Dans le cadre d'un quatrième projet, nous avons travaillé sur la radiothérapie interne sélective du CHC et développé un textbook outcome afin de proposer un outil de standardisation complet, adapté aux soins et à la recherche, dédié au déroulé de l’intervention. Cette étude s'est déroulée en deux étapes : (1) le comité de pilotage a d'abord dressé une liste exhaustive d’items candidats à refléter les composantes de l’intervention radiothérapie interne sélective RIS sur la base d'une analyse de la littérature, (2) puis a mené une enquête internationale et multidisciplinaire qui a abouti au textbook outcome final. Ce textbook outcome final se compose de 11 items répartis sur six domaines correspondant aux différentes étapes de la radiothérapie interne sélective et reflétant une intervention idéale. Tous ces items, sauf un, étaient appliqués dans les institutions de plus de 80 % des experts ayant participé à l’élaboration du textbook outcome. Notre travail fournit des domaines d'amélioration pour les ECR sur la RI à travers 1) l’accessibilité des résultats des essais afin de réduire le gaspillage de la recherche ; 2) l'enregistrement prospectif des essais pour assurer la qualité et la transparence ; 3) l'amélioration du reporting des essais avec des résumés décrivant les spécificités des interventions non-pharmacologiques; et 4) la standardisation des interventions via un outil capturant leurs dimensions essentielles.The randomized controlled trial (RCT) methodology was first used in interventional radiology (IR) in 1985 in a trial evaluating transarterial chemoembolization (TACE) for the treatment of hepatocellular carcinoma (HCC). The specialty has progressively adopted this evaluation method for new treatments and technical innovations. However, the application of this methodology to IR raises, as for other non-pharmacological treatments (TNPs) (i.e., involving treatments other than drugs), specific methodological issues related to the complexity of the interventions, the influence of care providers, the expertise of the center and the difficulties of blinding, which have a major influence on the planning, implementation and interpretation of RCTs. In a first project, we assessed the extent to which the results of registered RCTs assessing TACE for treating HCC were publicly available. Among 67 identified RCTs, including a total number of 11 599 participants, almost two-thirds did not yield any public results, either on the registry platform or in scientific journals. Underreporting of trial results is a major cause of wasted medical research since inaccessible research results fail to help both patients and clinicians. In a second project, we determined the proportion of RCTs on TACE for HCC, published after 2007, that were registered. We compared registered primary outcomes with those reported in publications to determine whether selective outcome reporting favored significant outcomes. We evidenced that half of these published RCTs were not registered, and when registered, one-third had major discrepancies between the registered and published primary outcomes. Selective outcome reporting favoring the trial results was observed in 7% of published reports. In a third project we assessed the completeness of reporting of abstracts in RCTs for liver IR and the impact of the publication of the CONSORT extension for NPT 2017 update. We assessed the evolution trend over time using a time-series analysis. We found that completeness of reporting was poor in abstracts of trials for liver IR and did not improve after the publication of the CONSORT-TNP statement. In a fourth project we worked on SIRT and developed a textbook outcome (TO) in order to propose a comprehensive standardization tool, suitable for routine care, clinical round, and research. This study involved two steps: (1) the steering committee first developed an extensive list of possible relevant items reflecting an optimal SIRT intervention based on a literature review, (2) then conducted an international and multidisciplinary survey which resulted in the final TO. This final TO consisted in 11 parameters across six domains corresponding to the different steps of a SIRT. Of these, all but one were applied in the institutions of >80% of experts. Our work provides areas of improvement for IR RCTs through 1) systematic publication of trial results, including negative results, to reduce research waste; 2) prospective registration of trials to ensure quality and transparency; 3) improved reporting of trials through abstracts providing specificities of non-pharmacological interventions; and 4) standardization of interventions through dedicated outcomes capturing its essential dimensions
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
Initiative on Superselective Conventional Transarterial Chemoembolization Results (INSPIRE)
Full text linkSeveral publications show that superselective conventional TransArterial ChemoEmbolization (cTACE), meaning cTACE performed selectively with a microcatheter positioned as close as possible to the tumor, improves outcomes, maximizing the anti-tumoral effect and minimizing the collateral damages of the surrounding liver parenchyma. Recent recommendations coming from the European Association for the Study of the Liver (EASL) and European Society of Medical Oncology (ESMO) highlighted that TACE must be used in Hepatocellular Carcinoma (HCC) “selectively targetable” and “accessible to supraselective catheterization.” The goal of the manuscript is to better define such population and to standardize superselective cTACE (ss-cTACE) technique. An expert panel with extensive clinical-procedural experience in TACE, have come together in a virtual meeting to generate recommendations and express their consensus. Experts recommend that anytime cTACE is proposed, it should be ss-cTACE, preferably with a 1.5–2.0 Fr microcatheter. Ideally, ss-cTACE should be proposed to patients with less than five lesions and a maximum number of two segments involved, with largest tumor smaller than 5 cm. Angio Cone-Beam Computed Tomography (CBCT) should be used to detect enhancing tumors, tumor feeders and guide tumor targeting. Whole tumor volume should be covered to obtain the best response. Adding peritumoral margins is encouraged but not mandatory. The treatment should involve a water-in-oil emulsion, whose quality is assessable with the “drop test.” Additional particulate embolization should be systematically performed, as per definition of cTACE procedure. Non-contrast CBCT or Multi-Detector Computed Tomography (MDCT) combined with angiography has been considered the gold standard for imaging during TACE, and should be used to assess tumor coverage during the procedure. Experts convene that superselectivity decreases incidence of adverse effects and improves tolerance. Experts recommend contrast-enhanced Computed Tomography (CT) as initial imaging on first follow-up after ss-cTACE, and Magnetic Resonance Imaging (MRI) if remaining tumor viability cannot be confidently assessed on CT. If no response is obtained after two ss-cTACE sessions within six months, patient must be considered unsuitable for TACE and proposed for alternative therapy. Patients are best served by multidisciplinary decision-making, and Interventional Radiologists should take an active role in patient selection, treatment allocation, and post-procedural care
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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