Excessive Coverage Research Articles

Automated detection of z-axis coverage with abdomen-pelvis computed tomography examinations.

Excessive cephalocaudal anatomic (Z-axis) coverage can lead to unnecessary radiation exposure to a patient. In this study, an automated computing model was developed for identifying instances of potentially excessive Z-axis coverage with abdomen-pelvis examinations. Eight patient and imaging attributes including patient gender, age, height, weight, volume CT dose index (CTDIvol), dose length product (DLP), maximum abdomen width, and maximum abdomen thickness were used to build a feedforward neural network model to predict a target Z-axis coverage whether it is an excessive or non-excessive Z-axis coverage scans. 264 CT abdomen-pelvis exams were used to develop the model which is validated using 10-fold cross validation. The result showed that 244 out of 264 exams (92.4%) correctly predicted Z-axis excessive coverage. The promising results indicate that this tool has the potential to be used for CT exams of the chest and colon, urography, and other site-specified CT studies having defined limited length.

Reliability of a new hip lateral view to quantify alpha angle in femoroacetabular impingement

BackgroundRadiographic measurement of the alpha angle (AA) in femoroacetabular impingement (FAI) is not well codified and invasive techniques such as MR- or CT-arthrography remain the gold standard. Excessive acetabular coverage described in pincer-type FAI can be seen on plain radiographs but has never been quantified and anterior center edge (ACE) angle, described on the false-profile view (FP) to measure anterior acetabular coverage has never been evaluated in FAI. HypothesisIn this study we wanted to determine if a plain radiograph could efficiently measure AA compared to CT-arthrography and if ACE could quantify the acetabular coverage in FAI. Materials and methodsWe developed a hip view combining a lateral view and a FP, called profile view in impingement position (PIP). Twenty-six patients operated for FAI had CT-arthrography, PIP and FP. Nineteen control subjects had the PIP. AA were measured twice by three raters and ACE once. We compared AA measured on patients between CT and PIP, on PIP between patients and controls, ACE measured on patients between PIP and FP, and did a reproducibility analysis. Means were compared by paired or unpaired t-tests; reproducibility was measured by intraclass correlation coefficient (ICC). ResultsMean AA was 65.8° (range, 48–85°) on CT-arthrography and 63.9° (range, 50–87°) on PIP (P>0.05). ICC for PIP measures were 0.8–0.9 for intra-rater and 0.6–0.9 for inter-rater reliability. Mean AA on PIP in patients was 63.3° (range, 52–87°) and 44.9° (range, 34–67°) in controls (P<0.001). Mean ACE was 26.8° (range, 14–41°) on PIP and 32.8° (range, 18–56°) on the FP (P=0.015). DiscussionThe PIP is a reliable view to measure the AA in FAI as measures on PIP and CT-arthrography were not significantly different with a good reproducibility. All of the painful hips and 2 controls had an AA>50°. PIP was not efficient to measure ACE. Level of evidenceLevel III, case-control study.

Increased Pericyte Coverage Mediated by Endothelial-Derived Fibroblast Growth Factor-2 and Interleukin-6 Is a Source of Smooth Muscle–Like Cells in Pulmonary Hypertension

Pericytes and their crosstalk with endothelial cells are critical for the development of a functional microvasculature and vascular remodeling. It is also known that pulmonary endothelial dysfunction is intertwined with the initiation and progression of pulmonary arterial hypertension (PAH). We hypothesized that pulmonary endothelial dysfunction, characterized by abnormal fibroblast growth factor-2 and interleukin-6 signaling, leads to abnormal microvascular pericyte coverage causing pulmonary arterial medial thickening. In human lung tissues, numbers of pericytes are substantially increased (up to 2-fold) in distal PAH pulmonary arteries compared with controls. Interestingly, human pulmonary pericytes exhibit, in vitro, an accentuated proliferative and migratory response to conditioned media from human idiopathic PAH endothelial cells compared with conditioned media from control cells. Importantly, by using an anti-fibroblast growth factor-2 neutralizing antibody, we attenuated these proliferative and migratory responses, whereas by using an anti-interleukin-6 neutralizing antibody, we decreased the migratory response without affecting the proliferative response. Furthermore, in our murine retinal angiogenesis model, both fibroblast growth factor-2 and interleukin-6 administration increased pericyte coverage. Finally, using idiopathic PAH human and NG2DsRedBAC mouse lung tissues, we demonstrated that this increased pericyte coverage contributes to pulmonary vascular remodeling as a source of smooth muscle-like cells. Furthermore, we found that transforming growth factor-β, in contrast to fibroblast growth factor-2 and interleukin-6, promotes human pulmonary pericyte differentiation into contractile smooth muscle-like cells. To the best of our knowledge, this is the first report of excessive pericyte coverage in distal pulmonary arteries in human PAH. We also show that this phenomenon is directly linked with pulmonary endothelial dysfunction.

Radiophobia and Trauma: Examining the Lasting Effects of the Fukushima Nuclear Disaster

The Fukushima nuclear disaster of March 2011 – unlike the earthquake and tsunami leading up to it – was not experienced directly or immediately for many. Its effects were, however, experienced belatedly, in the form of displacement and radiophobia, which have had a significant psychological impact on survivors. Moreover, excessive media coverage of the disaster allowed it to have a global impact not seen during previous nuclear disasters. Shion Sono’s film The Land of Hope, released in Japan in October of 2012, helps to illustrate the traumatic nature of a nuclear crisis through issues such as dislocation, media coverage, radiophobia, and distrust of the government.

Urban Lakes in Megacity Jakarta: Risk and Management Plan for Future Sustainability

The impact of urban development in the distinct surrounding inhabited areas on urban lakes in megacity Jakarta has been so pervasive that makes the lakes very vulnerable to environmental disturbances. High levels of disturbances to the urban lakes from urban development in the past and recent years, such as lake filling, land use change, shoreline encroachment, and garbage dump, have caused nearly 10 - 20% of urban lakes loss in megacity Jakarta. The consistency of lakes loss has been estimated from the old-Dutch map to the recent year maps indicating that the lakes continuously have been sacrificed for urban area development. In addition to the lake front destruction, siltation and the excessive macrophyte coverage have caused more than 25% of existing lakes shrinkage in area and volume and based on the lake morphology assessment, nearly 50% of lakes have been damaged. The lakes inurban village, rural village, agricultural and urban village – industrial areas are at high risk of lakefront landscape destruction, siltation/sedimentation, eutrophication and water pollution, including pathogenic bacteria and toxic pollutants contamination that can pose threat on human's health as results of untreated sewage inflow and storm water runoff to the lakes. The complexity of the problems faced by urban lakes in Jakarta requires a comprehensive management plan that is not only effective in maintaining the stability of lake ecosystem but also effective in improving urban life, such as socio-culture-economic conditions of people around the lakes. Fundamental requirement is that the urban lake should be managed according to its surrounding characteristics and conditions, and functional context.

Circumferential Reconstruction of Severe Acetabular Labral Damage Using Hamstring Allograft: Surgical Technique and Case Series

With excessive acetabular coverage, such as coxa profunda or protrusio, contact between the femoral neck and acetabular rim cause direct damage to the labrochondral junction, and indirect edge loading from a levering effect which may result in hip arthrosis. Arthrosis may be delayed or avoided by addressing the overcoverage and restoring mechanical function of the labrum. We describe four cases of adjunctive complete acetabular labral replacement for circumferential, irreparable labral injury using fresh frozen semitendinous allografts through surgical hip dislocation. Over a two-year period four patients (age range: 20 to 47 years) underwent surgical hip dislocation to address femoroacetabular impingement with rim trimming, femoral osteochondroplasty, and labral reconstruction. Pre- and postoperative patient reported outcomes were assessed by Oxford Hip Score (OHS), Hip Outcome Score (HOS), and Global Treatment Outcome (GTO) score. Disease progression was graded using AP pelvic radiographs and arthroMR. The average LCE correction was 18º (range 7-25º), achieving an average LCE of 33º (range 32-35) postoperatively. Using protected weight bearing all trochanteric osteotomies healed within six weeks after surgery. OA did not progress in any hips. Mean OHS and HOS scores improved 6.3 and 19.8 at one-year follow up. All four patients reported good results according to the GTO. There were two adverse events that resolved and did not affect outcome. Despite complex deformities and preexisting cartilage and labrum wear in this young cohort, three of four patients reported significant functional improvement after treatment of this rare condition. Preliminary experience with circumferential labral reconstruction using hamstring allografts is promising, although long-term data needs to be established.

Cross-Culturalism of Harry Potter

Seven books in the Harry series by J. K. Rowling have broken sales records worldwide. They have been made into films which have also attracted millions of fans, and the Harry brand has been a hallmark since the beginning of the new millennium. Fifteen years after publishing the first book in the heptalogy, e-books again made more than 1 million pounds in just three days in April 2012. The article Cross-Culturalism of Harry Potter examines what attracted readers to the first and then subsequent books in the Harry series and presents some of the cross-cultural implications in socio-linguistic, educational and psychological areas. It analyzes the reasons for the sales records around the world and why the books appeal to both young and adult population. It also includes some controversy following the series' world success. The research methods include: evaluation of the primary sources (seven books in the series), the media coverage, literary reviews by scholars such as Bloom and Thomas, literary critics' essays, and a survey of English language instructors in an educational institution. The main contributing factors to the global popularity of the series are: highly entertaining, well-plotted text with fantastic setting but also realistic references to the modern era; the text which continues the archetypal story-telling traditions, incorporating the contemporary socio-economic, political and educational issues; smart marketing; excessive media coverage; the Internet; the film industry involvement; and the universal human need to believe that good can triumph over evil.

Diretrizes para o tratamento da síndrome do anticorpo antifosfolipídeo

The antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by arterial and venous thrombosis, gestational morbidity and presence of elevated and persistently positive serum titers of antiphospholipid antibodies. The treatment of APS is still controversial, because any therapeutic decision potentially faces the risk of an insufficient or excessive antithrombotic coverage associated with anticoagulation and its major adverse effects. This guideline was elaborated from nine relevant clinical questions related to the treatment of APS by the Committee of Vasculopathies of the Brazilian Society of Rheumatology. Thus, this study aimed at establishing a guideline that included the most relevant and controversial questions in APS treatment, based on the best scientific evidence available. The questions were structured by use of the PICO (patient, intervention or indicator, comparison and outcome) process, enabling the generation of search strategies for evidence in the major primary scientific databases (MEDLINE/PubMed, Embase, Lilacs, Scielo, Cochrane Library, Premedline via OVID). A manual search for evidence and theses was also conducted (BDTD and IBICT). The evidence retrieved was selected based on critical assessment by using discriminatory instruments (scores) according to the category of the therapeutic question (JADAD scale for randomized clinical trials and Newcastle-Ottawa scale for non-randomized studies). After defining the potential studies to support the recommendations, they were selected according to level of evidence and grade of recommendation, according to the Oxford classification.

Guidelines for the treatment of antiphospholipid syndrome

The antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by arterial and venous thrombosis, gestational morbidity and presence of elevated and persistently positive serum titers of antiphospholipid antibodies. The treatment of APS is still controversial, because any therapeutic decision potentially faces the risk of an insufficient or excessive antithrombotic coverage associated with anticoagulation and its major adverse effects. This guideline was elaborated from nine relevant clinical questions related to the treatment of APS by the Committee of Vasculopathies of the Brazilian Society of Rheumatology. Thus, this study aimed at establishing a guideline that included the most relevant and controversial questions in APS treatment, based on the best scientific evidence available. The questions were structured by use of the PICO (patient, intervention or indicator, comparison and outcome) process, enabling the generation of search strategies for evidence in the major primary scientific databases (MEDLINE/PubMed, Embase, Lilacs, Scielo, Cochrane Library, Premedline via OVID). A manual search for evidence and theses was also conducted (BDTD and IBICT). The evidence retrieved was selected based on critical assessment by using discriminatory instruments (scores) according to the category of the therapeutic question (JADAD scale for randomized clinical trials and Newcastle-Ottawa scale for non-randomized studies). After defining the potential studies to support the recommendations, they were selected according to level of evidence and grade of recommendation, according to the Oxford classification.

Prévalence des anomalies acétabulaires associées à une déformation en crosse de pistolet dans la coxarthrose

Acetabular retroversion, excessive acetabular coverage and abnormal head-neck-junction with a so-called “pistol-grip-deformity” were added to the classical description of hip dysplasia to describe pathological hip morphology. The aim of the current study was the detection of pathological acetabular geometry in patients with an abnormal head-neck-junction. Femoro-acetabular impingement and hip dysplasia features are frequent in patients with end-stage osteoarthritis before 60 years of age. We analysed our data bank retrospectively for all patients who received a Total Hip Arthroplasty (THA) due to end-stage osteoarthritis before the age of 60 years. The pelvic-views and the Dunn-view of these patients were screened for an abnormal head-neck-junction by measuring the head-ratio and the alpha-angle. An orthopaedic surgeon and a radiologist did this independently. These radiographies were measured for signs of acetabular dysplasia, excessive acetabular coverage and crossing sign. A consecutive series of 135 total hip arthroplasties were performed in patients aged less or equal to 60 years because of end-stage osteoarthritis. From these, 81 patients were classified as having an abnormal head-neck-junction. The mean head-ratio in these 81 patients was 1.52 ± 0.35, the mean alpha-angle was 62.5° ± 9.3°. The mean CE-angle of these 81 patients was 35.8° ± 10.4°, the mean CA-angle was 36.7° ± 5.7°, the mean depth-width-ratio was 49.1 ± 10, the mean extrusion-index was 19.1 ± 9.2 and the mean CCD-angle was 131.7° ± 7.3°. Of these 81 hips, 14 had isolated pistol grip deformity, while 11 hips had associated dysplasia, 38 had excessive acetabular coverage, and 14 had crossing sign. In addition, a crossing sign was identified in four of the 11 dysplastic hips and 19 of the 38 of the hips having excessive acetabular coverage. There was no statistically significant difference in regard to the age between the four groups ( P = 0.087). In contrast, the hips that had excessive acetabular coverage had increased CE angle (44.6° ± 7.2°) and decreased extrusion index (12.6 ± 6.5) ( P < 0.001), while dysplastic hips had increased roof obliquity (17.5° ± 4.5°) and increased extrusion index (29.6 ± 9.1) as well as decreased CE-angle (20.7° ± 3.0°) ( P < 0.001). There is a high coincidence of radiographic findings associated with an abnormal head-neck-junction consisting in excessive acetabular coverage and retroversion as well as hip dysplasia. These results advocate for restoring of the normal anatomy at the early stage to prevent end-stage osteoarthritis. Level IV retrospective historical study.

Convolution-Superposition Based IMRT Plan Study for the PTV Containing the Air Region: A Prostate Cancer Case

In prostate IMRT planning, the planning target volume (PTV), extended from a clinical target volume (CTV), often contains an overlap air volume from the rectum, which poses a problem inoptimization and prescription. This study was aimed to establish a planning method for such a case. There can be three options in which volume should be considered the target during optimization process; PTV including the air volume of air density (‘airOpt’), PTV including the air volume of density value one, mimicking th e tissue material (‘density1Opt’), and PTV excluding the air volume (‘noAirOpt’). Using 10 MV photon beams, seven field IMRT plans for each target were created with the same parameter condition. For these three cases, DVHs for the PTV, bladder and the rectum were compared. Also, the dose coverage for the CTV and the shifted CTV were evaluated in which the shifted CTV was a copied and translated virtual CTV toward the rectum inside the PTV, thus occupying the initial position of the overlap air volume, simulating the worst condition for the dose coverage in the target. Among the three options, only density1Opt plan gave clinically acceptable result in terms of target coverage and maximum dose. The airOpt plan gave exceedingly higher dose and excessive dose coverage for the target volume whereas noAirOpt plan gave underdose for the shifted CTV. Therefore, for prostate IMRT plan, having an air region in the PTV, density modification of the included air to the value of one, is suggested, prior to optimization and prescription for the PTV. This idea can be equally applied to any cases including the head and neck cancer with the PTV having the overlapped air region. Further study is being under process.

Causes and Consequences of Labelling Gifted Pupils at Selected Elementary Schools

The article describes qualitative research analyzing causes and consequences of labelling gifted pupils. Causes and consequences were identified after an analysis of semi-structured interviews with gifted pupils, their classmates and teachers. Identified causes included certain pedagogical strategies such as excluding a gifted pupil from a group of their peers, using specific names for classes, excessive media coverage of specialized classes and pupils. Labelling was further promoted by a curriculum differing in its content, processes and materials offered to gifted pupils only. Consequences of labelling included ostracism and ridiculing of gifted pupils by their classmates, rivalry and hostility. The article concludes with proposals which might help to reduce labelling.

The prevalence of acetabular anomalies associated with pistol-grip-deformity in osteoarthritic hips

Acetabular retroversion, excessive acetabular coverage and abnormal head-neck-junction with a so-called "pistol-grip-deformity" were added to the classical description of hip dysplasia to describe pathological hip morphology. The aim of the current study was the detection of pathological acetabular geometry in patients with an abnormal head-neck-junction. Femoroacetabular impingement and hip dysplasia features are frequent in patients with end-stage osteoarthritis before 60 years of age. We analysed our data bank retrospectively for all patients who received a Total Hip Arthroplasty (THA) due to end-stage osteoarthritis before the age of 60 years. The pelvic-views and the Dunn-view of these patients were screened for an abnormal head-neck-junction by measuring the head-ratio and the alpha-angle. An orthopaedic surgeon and a radiologist did this independently. These radiographies were measured for signs of acetabular dysplasia, excessive acetabular coverage and crossing sign. A consecutive series of 135 total hip arthroplasties were performed in patients aged less or equal to 60 years because of end-stage osteoarthritis. From these, 81 patients were classified as having an abnormal head-neck-junction. The mean head-ratio in these 81 patients was 1.52±0.35, the mean alpha-angle was 62.5°±9.3°. The mean CE-angle of these 81 patients was 35.8°±10.4°, the mean CA-angle was 36.7°±5.7°, the mean depth-width ratio was 49.1±10, the mean extrusion index was 19.1±9.2 and the mean CCD-angle was 131.7°±7.3°. Of these 81hips, 14 had isolated pistol-grip-deformity, while 11 hips had associated dysplasia, 38 had excessive acetabular coverage, and 14 had crossing sign. In addition, a crossing sign was identified in four of the 11 dysplastic hips and 19 of the 38 of the hips having excessive acetabular coverage. There was no statistically significant difference in regard to the age between the four groups (P=0.087). In contrast, the hips that had excessive acetabular coverage had increased CE-angle (44.6°±7.2°) and decreased extrusion index (12.6±6.5) (P<0.001), while dysplastic hips had increased roof obliquity (17.5°±4.5°) and increased extrusion index (29.6±9.1), as well as decreased CE-angle (20.7°±3.0°) (P<0.001). There is a high coincidence of radiographic findings associated with an abnormal head-neck-junction consisting in excessive acetabular coverage and retroversion as well as hip dysplasia. These results advocate for restoring of the normal anatomy at the early stage to prevent end-stage osteoarthritis. Level IV retrospective historical study.

On the problem of inference for inequality measures for heavy‐tailed distributions

We consider the class of heavy‐tailed income distributions and show that the shape of the income distribution has a strong effect on inference for inequality measures. In particular, we demonstrate how the severity of the inference problem responds to the exact nature of the right tail of the income distribution. It is shown that the density of the studentized inequality measure is heavily skewed to the left, and that the excessive coverage failures of the usual confidence intervals are associated with excessively low estimates of both the point measure and the variance. For further diagnostics, the coefficients of bias, skewness and kurtosis are derived and examined for both studentized and standardized inequality measures. These coefficients are also used to correct the size of confidence intervals. Exploiting the uncovered systematic relationship between the inequality estimate and its estimated variance, variance stabilizing transforms are proposed and shown to improve inference significantly.

Impact of prior probabilities of MRSA as an infectious agent on the accuracy of the emerging molecular diagnostic tests: a model simulation

ObjectivesTraditional microbiology identification takes 48–72 h to complete. This lag forces clinicians to rely on broad-spectrum empiric coverage. To address this gap, manufacturers are developing rapid molecular diagnostics (RMD). We...

Analysis of Consumer Behavior in the Tokyo Metropolitan Area after the Great East Japan Earthquake

Rolling blackouts and commodity shortages profoundly disturbed the lives of citizens in the Tokyo metropolitan area following the Great East Japan Earthquake. Further, negative images of produce suspected of being contaminated by radioactivity from the nuclear accident continue to plague Japan′s agricultural sector. This study attempts to assist future disaster management plans by investigating the causes of and factors behind consumer behavior that manifests itself in such problems.A survey of adult female residents of Chiba City conducted in April, 2011, one month following the earthquake, is qualitatively and quantitatively analyzed. Our findings indicate consumers who are more likely to act problematically by stocking or delaying purchases tended to be younger, full-time housewives, who were unprepared for disasters, but had experienced emergency situations (such as shortages or blackouts), and who felt a sense of concern and anxiety about radioactive contamination at large. A vicious cycle, in which excessive media coverage was focused on the stockpiling behavior of only a minority of consumers, heightened market demands and perpetuated stockpiling, is also noted.

Application of the NFPA 654 dust layer thickness criteria—recognizing the hazard

AbstractThis article is an overview of the National Fire Protection Association (NFPA) 654 layer thickness criteria, including the 2011 Tentative Interim Amendment, and potential misinterpretations that could result in failure to recognize the hazard. Potential misinterpretations include allowing excessive floor area coverage, failure to account for layers thicker than the threshold, and failure to account for layers on equipment. The thickness criteria are applied to real‐life example situations, illustrating application of the equations. Practical guidance is provided for establishing an initial housekeeping plan, monitoring accumulation, and documenting compliance for both existing and new installations. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2012

Pathologie labrale et conflits de hanche

The acetabular labrum, a fibrocartilaginous structure essential to the proper functioning of the hip joint, may be damaged from a variety of conditions including femoroacetabular impingement. FAI is defined by abnormal contact between the femur and acetabulum and is characterized by an underlying morphological abnormality of the femur (dysplastic bump at the head/neck junction, Cam effect), acetabulum (excessive coverage, Pincer effect), or both. The abnormal morphology is suspected on plain films and additional evaluation with either CT or MR arthrography is then performed. The role of the radiologist is to describe the imaging findings while allowing the clinician to make the diagnosis based on clinical symptoms (groin pain, reduced internal rotation). Comprehensive evaluation of the underlying structural abnormalities and associated lesions is important to optimize surgical management with the goal of reducing painful symptoms, improve range of motion and prevent early hip joint degeneration.

Prevalence of Radiographic Findings Thought to Be Associated with Femoroacetabular Impingement in a Population-based Cohort of 2081 Healthy Young Adults

To report the prevalence of qualitative radiographic findings for femoroacetabular impingement (FAI) and associations among them and to characterize the inter- and intraobserver variability of these interpretations. This study is part of an institutional review board-approved population-based prospective follow-up of 2081 of 4006 (participation rate, 51.9%) young adults (874 [42.0%] male participants, 1207 [58.0%] female participants; mean age, 18.6 years) who took part in a randomized hip trial on developmental dysplasia of the hip. All participants gave informed consent. Two pelvic radiographs were obtained. Pistol-grip deformity, focal femoral neck prominence, and flattening of the lateral head, all suggestive of cam-type impingement, and the posterior wall sign, excessive acetabular coverage, and crossover sign, all suggestive of pincer-type impingement, were assessed subjectively by an experienced radiologist. To assess inter- and intraobserver agreement, images from 350 examinations were read independently twice by two observers. Cam-type deformities were seen in 868 male and 1192 female participants, respectively, as follows: pistol-grip deformity, 187 (21.5%) and 39 (3.3%); focal femoral neck prominence, 89 (10.3%) and 31 (2.6%); and flattening of the lateral femoral head, 125 (14.4%) and 74 (6.2%). Pincer-type deformities were seen in the same numbers of male and female participants, respectively, as follows: posterior wall sign, 203 (23.4%) and 131 (11.0%); and excessive acetabular coverage, 127 (14.6%) and 58 (4.9%) (all P < .001, according to sex distribution). The crossover sign was seen in 446 (51.4%) and 542 (45.5%) of the male and female participants, respectively (P = .004). There was a high degree of coexistence (odds ratio [OR] > 2) among most FAI findings. Interobserver agreement was good to very good (κ = 0.74-0.84) in rating cam- and pincer-type findings. Intraobserver agreement was moderate or good (κ = 0.49-0.80) for all findings for both observers. Overall, radiographic FAI findings are quite common in a population of healthy young adults, especially in males, with a high degree of coexistence among most findings (OR > 2).

Du nuage à la cascade : une vision pessimiste des processus décisionnels

Résumé Cet article vise à répondre à la question de recherche suivante : comment la sur-médiatisation modifie-t-elle le processus de prise de décision effectué par un expert confronté à une situation de crise ? A partir de l’étude du cas du nuage de cendres volcaniques qui a traversé le ciel européen en avril 2010, nous observons le paradoxe suivant : confronté à une décision complexe, risquée et internationale, les experts prennent une décision homogène, unanime et simple. Nous exposons alors les caractéristiques des processus décisionnels en situation de sur-médiatisation.