Ischémie-reperfusion cérébrale post- thrombectomie mécanique : modélisation probabiliste en artériographie à la phase hyper aigue et modélisation réaliste métabolique à la phase aigüe

Neurovascular pathologies, in the forefront of which are strokes, are a public health issue for which it is important to offer the most effective, standardized, homogeneous and personalized treatment.Strokes are caused in 80 % of cases by cerebral ischemia (CI), secondary to the interruption of cerebral blood flow. When a clot clogs a cerebral artery, it leads to a decrease in cerebral perfusion,falling below the physiological threshold of cerebral blood flow. This drop in perfusion below the threshold leads to a decrease in the blood supply of oxygen and metabolites necessary for the survival of neurons and supporting tissue. This is called cerebral hypoxemia. This phenomenon rapidly leads to "neuronal silence", also called "penumbra zone", and then to irreversible necrosis, i.e. cerebral infarction, through neuronal death via depolarization, oxidative stress and excitotoxicity mechanisms.Each step of the patient management is guided by imaging : from the initial diagnostic imaging guiding the treatment and the orientation of the patient to the therapeutic interventional imaging allowing the removal of the occlusions and the immediate post-therapeutic imaging guiding the further management by allowing the diagnosis of the complications.In a first step, we have developed an algorithm for the analysis of arteriograms from a wavelet decomposition in order to evaluate in an automated and quantitative way the reperfusion after thrombectomy.Secondly, we studied the metabolic consequences of ischemia-reperfusion in proton and phosphorus spectroscopy using a logistic regression model based on categorical variables.Les pathologies neurovasculaires, au premier rang desquelles les accidents vasculaires cérébraux, sont un enjeu de santé publique pour lequel il est important d’offrir une prise en charge la plus efficace, standardisée, homogène mais aussi personnalisée.Les accidents vasculaires cérébraux sont causés dans 80 % des cas par une ischémie cérébrale (IC), secondaire à l’interruption du flux sanguin cérébral. Lorsqu’un caillot bouche une artère cérébrale, cela conduit à une diminution de la perfusion cérébrale, passant en dessous du seuil d’autorégulation physiologique du débit sanguin cérébral. Cette chute de la perfusion en dessous de seuil entraîne ainsi une diminution de l’apport sanguin en oxygène et métabolites nécessaires à la survie des neurones et du tissu de soutien. Ceci s’appelle l’hypoxémie cérébrale. Ce phénomène conduit rapidement au " silence neuronal ", appelé aussi " zone de pénombre ", puis à la nécrose irréversible, c’est-à-dire à l’infarctus cérébral, par mort neuronale via des mécanismes de dépolarisation, de stress oxy-datif et d’excitotoxicité.Chacune des étapes de la prise en charge des patients est guidée par l’imagerie : de l’imagerie diagnostique initiale guidant le traitement et l’orientation du patient à l’imagerie interventionnelle thérapeutique permettant de lever les occlusions en passant par l’imagerie post thérapeutique immédiate permettant de guider la suite de la prise en charge en permettant dediagnostiquer les complications.Dans un premier temps nous avons réalisé un algorithme d’analyse des artériographies issus d’une décomposition d’ondelettes afin d’évaluer de manière automatisée et quantitative la reperfusion après thrombectomie.Dans un second temps nous avons étudié les conséquences métaboliques de l’ischémie reperfusion en spectroscopie proton et phosphore à l’aide d’un modèle issu d’une régression logistique basée sur des variables catégorielles

Post-mechanical thrombectomy cerebral ischemia-reperfusion : probabilistic modeling in hyperacute arteriography and metabolic prognostic modeling in the acute phase

Les pathologies neurovasculaires, au premier rang desquelles les accidents vasculaires cérébraux, sont un enjeu de santé publique pour lequel il est important d’offrir une prise en charge la plus efficace, standardisée, homogène mais aussi personnalisée.Les accidents vasculaires cérébraux sont causés dans 80 % des cas par une ischémie cérébrale (IC), secondaire à l’interruption du flux sanguin cérébral. Lorsqu’un caillot bouche une artère cérébrale, cela conduit à une diminution de la perfusion cérébrale, passant en dessous du seuil d’autorégulation physiologique du débit sanguin cérébral. Cette chute de la perfusion en dessous de seuil entraîne ainsi une diminution de l’apport sanguin en oxygène et métabolites nécessaires à la survie des neurones et du tissu de soutien. Ceci s’appelle l’hypoxémie cérébrale. Ce phénomène conduit rapidement au " silence neuronal ", appelé aussi " zone de pénombre ", puis à la nécrose irréversible, c’est-à-dire à l’infarctus cérébral, par mort neuronale via des mécanismes de dépolarisation, de stress oxy-datif et d’excitotoxicité.Chacune des étapes de la prise en charge des patients est guidée par l’imagerie : de l’imagerie diagnostique initiale guidant le traitement et l’orientation du patient à l’imagerie interventionnelle thérapeutique permettant de lever les occlusions en passant par l’imagerie post thérapeutique immédiate permettant de guider la suite de la prise en charge en permettant dediagnostiquer les complications.Dans un premier temps nous avons réalisé un algorithme d’analyse des artériographies issus d’une décomposition d’ondelettes afin d’évaluer de manière automatisée et quantitative la reperfusion après thrombectomie.Dans un second temps nous avons étudié les conséquences métaboliques de l’ischémie reperfusion en spectroscopie proton et phosphore à l’aide d’un modèle issu d’une régression logistique basée sur des variables catégorielles.Neurovascular pathologies, in the forefront of which are strokes, are a public health issue for which it is important to offer the most effective, standardized, homogeneous and personalized treatment.Strokes are caused in 80 % of cases by cerebral ischemia (CI), secondary to the interruption of cerebral blood flow. When a clot clogs a cerebral artery, it leads to a decrease in cerebral perfusion,falling below the physiological threshold of cerebral blood flow. This drop in perfusion below the threshold leads to a decrease in the blood supply of oxygen and metabolites necessary for the survival of neurons and supporting tissue. This is called cerebral hypoxemia. This phenomenon rapidly leads to "neuronal silence", also called "penumbra zone", and then to irreversible necrosis, i.e. cerebral infarction, through neuronal death via depolarization, oxidative stress and excitotoxicity mechanisms.Each step of the patient management is guided by imaging : from the initial diagnostic imaging guiding the treatment and the orientation of the patient to the therapeutic interventional imaging allowing the removal of the occlusions and the immediate post-therapeutic imaging guiding the further management by allowing the diagnosis of the complications.In a first step, we have developed an algorithm for the analysis of arteriograms from a wavelet decomposition in order to evaluate in an automated and quantitative way the reperfusion after thrombectomy.Secondly, we studied the metabolic consequences of ischemia-reperfusion in proton and phosphorus spectroscopy using a logistic regression model based on categorical variables

Analysis of Unsteady Flow in Over-expanded Nozzle

International audienceAn over-expanded jet in a Truncated-Ideally Contoured(TIC) nozzle is investigated to identify the phenomena involved in the generation of lateral pressure forces. Theoperating conditions correspond to the generation of wallpressure fluctuations of maximal amplitude for the presentgeometry. Synchronized time-resolved velocity and wallpressure data are measured in planes normal to the jet axisdownstream of the nozzle and along azimuthal rings of pressure sensors within the separated region in the nozzle. Thefirst fluctuating modes of internal pressure and external velocity are found to be significantly correlated in a narrowfrequency range. A Delayed Detached Eddy Simulation(DDES) is carried out to reproduce the global flow dynamics. It is shown in this case that lateral forces are dominatedby the signature of this tonal behaviour

Femoral head subchondral impaction on CT: what does it mean in patients with acetabular fracture?

To evaluate the prevalence of isolated femoral head impactions associated with acetabular fractures and to assess whether impactions may be predictive of the development of delayed major complications requiring total hip arthroplasty

Emergency Computed Tomography: How Misinterpretations Vary According to the Periods of the Nightshift?

To evaluate the accuracy of initial computed tomography (CT) interpretations made by radiology residents during nightshifts in the emergency department

Early Metabolic Alteration Predicts Outcome With Middle Cerebral Artery Occlusion Treated by Mechanical Thrombectomy

Background Predicting clinical outcome based on either the postprocedural recanalization score (modified treatment in cerebral infarction) or the initial National Institute of Health Stroke Scale (NIHSS) clinical score performed immediately after the acute phase remains controversial. The gold standard to predict clinical outcome is the NIHSS score with diffusion weighted imaging. However, magnetic resonance spectroscopy could provide useful metabolic informations. Our study aimed to determine early metabolic factors predictive of long‐term clinical outcome after acute ischemic stroke in patients with middle cerebral artery occlusion successfully treated by mechanical thrombectomy. Methods Patients with proximal middle cerebral artery occlusion, an NIHSS score greater than 6 and successfully treated by mechanical thrombectomy with or without intravenous therapy were included. All patients underwent within 24 hours after mechanical thrombectomy, brain magnetic resonance imaging examination with multivoxel proton‐phosphorus‐magnetic resonance spectroscopy. Functional disability at 90 days with reference to pre‐stroke activities was categorized using the modified Rankin scale. Metabolite ratios were measured and confronted to modified Rankin scale. Results A total of 49 patients were included with initial mean NIHSS of 15.19±5.48. Time delay between: onset‐thrombectomy was 6.77 hours±3.22, thrombectomy‐magnetic resonance imaging was 29.83 hours±15.01. Results in the lesion compared with the contralateral area show an increase of Lac/Cr (0.88 versus 0.21; P<10−10) and a decrease of PhosphoMonoEster/PhosphoDiEster (0.80 versus 0.83; P=0.00165). Lac/Cr in the lesion was significantly higher in the poor outcome group than in the favorable outcome group (1.03±0.41 and 0.75±0.42; P=0.01). Our model built with NIHSS+proton‐magnetic resonance spectroscopy compared with the gold standard model (NIHSS+diffusion weighted imaging) is better (85.29% versus 77.55%) to predict clinical outcome. Conclusion Our study shows that early Lac/Cr alteration visible 24 hours after stroke is a strong predictor of 90 days clinical outcome for middle cerebral artery occlusion patients successfully treated by mechanical thrombectomy. Our NIHSS+proton‐magnetic resonance spectroscopy model is the first to predict patients’ long‐term functional outcome with an accuracy of 85.3%, superior to existing models including diffusion weighted imaging

Comparative evaluation of minimally invasive ‘tibial tuberoplasty’ surgical technique versus conventional open surgery for Schatzker II–III tibial plateau fractures: design of a multicentre, randomised, controlled and blinded trial (TUBERIMPACT study)

International audienceINTRODUCTION:Fractures of the tibial plateau are in constant progression. They affect an elderly population suffering from a number of comorbidities, but also a young population increasingly practicing high-risk sports. The conventional open surgical technique used for tibial plateau fractures has several pitfalls: bone and skin devascularisation, increased risks of infection and functional rehabilitation difficulties. Since 2011, Poitiers University Hospital is offering to its patients a new minimally invasive technique for the reduction and stabilisation of tibial plateau fractures, named 'tibial tuberoplasty'. This technique involves expansion of the tibial plateau through inflation using a kyphoplasty balloon, filling of the fracture cavity with cement and percutaneous screw fixation. We designed a study to evaluate the quality of fracture reduction offered by percutaneous tuberoplasty versus conventional open surgery for tibial plateau fracture and its impact on clinical outcome.METHODS AND ANALYSIS:This is a multicentre randomised controlled trial comparing two surgical techniques in the treatment of tibial plateau fractures. 140 patients with a Schatzker II or III tibial plateau fracture will be recruited in France. They will be randomised either in tibial tuberoplasty arm or in conventional surgery arm. The primary outcome is the postoperative radiological step-off reduction blindly measured on CT scan (within 48 hours post-op). Additional outcomes include other radiological endpoints, pain, functional abilities, quality of life assessment and health-economic endpoints. Outcomes assessment will be performed at baseline (before surgery), at day 0 (surgery), at 2, 21, 45 days, 3, 6, 12 and 24 months postsurgery.ETHICS AND DISSEMINATION:This study has been approved by the ethics committee Ile-De-France X and will be conducted in accordance with current Good Clinical Practice (GCP) guidelines, Declaration of Helsinki and standard operating procedures. The results will be disseminated through presentation at scientific conferences and publication in peer-reviewed journals