Application de la mécanique des fluides numérique à l'imagerie de la pathologie de l'aorte thoracique et des traitements endovasculaires modernes par pose d'endoprothèse

La prise en charge des malades porteurs de maladie de l'aorte thoracique a été révolutionnée pendant ces dernières années par l'introduction du traitement endovasculaire par implantation d'endoprothèse, présenté à la communauté scientifique sur le New England Journal of Medicine en 1994. Depuis ce temps, une multitude d'études ont alimenté la littérature scientifique spécialisée. Cependant, même si les résultats cliniques ont étés encourageants au point de proposer la nouvelle thérapie comme référence dans certaines indications, notamment en cas d'urgence, moins d'attention a été réservée aux conséquences fonctionnelles liées à la pose du dispositif à l'intérieur du vaisseau. A partir de l'état vasculaire natif, quelles sont les modifications induites par l'endoprothèse sur l'anatomie et l'hémodynamique de l'aorte ? Cette question est le fil conducteur de mon projet de recherche. J'aborde dans cette thèse l'ensemble des problèmes liés au rôle de l'imagerie vasculaire fonctionnelle dans la prise en charge du patient aux différentes étapes de la méthodologie développée. Les simulations hémodynamiques par application de la mécanique des fluides numérique (MFN) sont, à ce jour, la seule méthode proposée pour obtenir une imagerie fonctionnelle de l'aorte thoracique pour l'évaluation des endoprothèses. En comptant sur une solide expérience au sein du laboratoire OCFIA avec la fusion des techniques d'imagerie classiques et la MFN, l'objectif des travaux de cette thèse de science est le développement de la filière de recherche dédiée à l'application de la mécanique des fluides numérique pour l'exploration hémodynamique de l'aorte thoracique et des conséquences des nouveaux traitements endovasculaires par implantation d'endoprothèse. Le projet a été structuré en deux axes : le premier a été focalisé sur l'évaluation d'une méthode d'imagerie fonctionnelle visant la reconstruction de conditions réalistes et spécifiques à l'aide du couplage entre l'imagerie par résonance magnétique (IRM) et la MFN. La méthodologie, mise au point au sein du laboratoire OCFIA, permet d'obtenir des vraies cartographies hémodynamiques centrées sur des paramètres différents, notamment la vitesse, la vorticité du flux et la force de cisaillement pariétal. La participation des médecins de l'équipe a permis de vérifier la faisabilité de la méthode in vivo et de comparer les études fonctionnelles aux données anatomiques pour en évaluer la fiabilité. Le deuxième axe du projet a été conçu pour développer l'application de la MFN à la recherche clinique. Dans ce but, le code Xflow a été choisi pour le couplage avec le scanner afin de réaliser une analyse quantitative de deux paramètres (le WSS et la vorticité), sur une série de 30 patients pour mettre en évidence les éventuelles modifications de l'état fonctionnel aortique avant et après mise en place d'endoprothèse. Le développement de la méthode scanner-MFN a permis d'évaluer, dans un premier temps, l'impact anatomique de l'implantation sur 60 géométries aortiques, un travail original dans le cadre de la littérature spécialisée. Ensuite, la base des données a été exploitée pour obtenir les simulations numériques à l'aide de différents outils à l'intérieur du logiciel solveur. Une extraction ponctuelle a été réalisée sur les zones d'implantation, permettant de confirmer l'hypothèse concernant les conséquences fonctionnelles du traitement sur le vaisseau natif. La publication des travaux dans des revues internationales incite les futurs développements pour optimiser l'application de nouvelles méthodes à la recherche clinique afin d'individualiser le rôle des facteurs fonctionnels soit dans le contexte du suivi des patients, soit dans l'évaluation de l'efficacité des dispositifs.Since 1994, when thoracic endovascular aortic repair (TEVAR) was presented to the medical community on the New England Journal of Medicine, the management of the aortic pathologies has dramatically changed in favour of a less invasive treatment associated with lower mortality and morbidity rates. A multitude of clinical trials, institutional registers and case reports has enriched the scientific literature and consecrated the new therapy which has been recently proposed as the new gold standard for such a theatre as the acute traumatic aortic rupture (ATAR). Nevertheless, little is known about the consequences of the device implantation on the native aortic status, in term either of anatomy and function. All routinely available techniques certainly provide well-detailed analysis of the aortic morphology but, so far, none of them allows for a functional exploration of the post-implantation status of the patients treated by TEVAR. The purpose of this PhD project, run over three years, was to develop functional vascular imaging techniques based on the combination of magnetic resonance (MR) and computed tomography (CT) with the CFD technology for the analysis of the thoracic aortic haemodynamics before and after the implantation of an endograft. Two main research lines have been followed: the first one was focused on the MRI-CFD combination for performing virtual simulations of the flow behaviour based on realistic patient-specific conditions. The multidisciplinary team of the OCFIA research laboratory implemented the methodology that was tested in vivo for the application in the thoracic aorta. Three-dimensional functional maps of the flow patterns were obtained and different parameters such as the velocity, vorticity and wall shear stress were qualitatively analyzed. The functional maps were compared with the morphologic images to assess their reliability. The second research line was dedicated to the application of the CFD-vascular imaging to a clinical study. The Xflow code was used with a CT combined approach for a systematic quantitative evaluation on a series of 30 patients; pre and post operative geometries were extracted and analyzed in order to detect the anatomical modifications before and after the implantation. The 3D image dataset was thereafter used for launching the CFD runs by a lagrangian approach. A quantitative comparative analysis of the wall shear stress and the vorticity was focused on the landing zones by means of two different tools. The outcomes confirmed the hypothesis of the impact of the endovascular treatment on the aortic status in terms of anatomy and functional changes. The application of the CFD methods for the functional evaluation of the thoracic aorta appeared feasible both before and after a stent-graft implantation. Over the three years two different papers have been accomplished and gained attention for publication on international journals. An implementation of the techniques is necessary to develop the clinical application of the CFD methods and weigh up their role in the whole patient management

Image fusion performed with noncontrast computed tomography scans during endovascular aneurysm repair

We report two endovascular aneurysm repair procedures achieved under image fusion guidance accomplished with noncontrast injected preoperative computed tomography scans. Such use of this advanced imaging application reduces contrast media injection volume (respectively, 27 and 24 mL throughout the patients' hospital course). No changes in creatinine clearance occurred after the procedures. Contrast-enhanced ultrasound imaging confirmed technical success in both cases

Comment on Jaworska, J. et al. Consensus on the application of lung ultrasound in pneumonia and bronchiolitis in children

To the editor: [...

Predictors of poor blood pressure control assessed by 24 hour monitoring in patients with type B acute aortic dissection

The chronic management of post-acute aortic dissection (AD) of the descending aorta (Type B) is based on optimal control of blood pressure (BP), with a target BP < 135/80 mmHg. The aim of our study was to determine and verify effective blood pressure control with an objective measurement method and to identify predicting factors

Future of IR: Emerging Techniques, Looking to the Future…and Learning from the Past

Innovation has been the cornerstone of interventional radiology since the early years of the founders, with a multitude of new therapeutic approaches developed over the last 50 years. What is the future holding for us? This article presents an overview of the in-coming developments that are catching on at this moment, particularly focusing on three items: the new applications of existing techniques, particularly embolotherapy and interventional oncology; the cutting-edge devices; the imaging technologies at the forefront of the image-guidance. Besides this, clinical vision and patient relation remain crucial for the future of the discipline

Eligibility criteria for pediatric patients who may benefit from anti SARS-CoV-2 monoclonal antibody therapy administration: an Italian inter-society consensus statement

The fast diffusion of the SARS-CoV-2 pandemic have called for an equally rapid evolution of the therapeutic options.The Human recombinant monoclonal antibodies (mAbs) have recently been approved by the Food and Drug Administration (FDA) and by the Italian Medicines Agency (AIFA) in subjects aged ≥12 with SARS-CoV-2 infection and specific risk factors.Currently the indications are specific for the use of two different mAbs combination: Bamlanivimab+Etesevimab (produced by Eli Lilly) and Casirivimab+Imdevimab (produced by Regeneron).These drugs have shown favorable effects in adult patients in the initial phase of infection, whereas to date few data are available on their use in children.AIFA criteria derived from the existing literature which reports an increased risk of severe COVID-19 in children with comorbidities. However, the studies analyzing the determinants for progression to severe disease are mainly monocentric, with limited numbers and reporting mostly generic risk categories.Thus, the Italian Society of Pediatrics invited its affiliated Scientific Societies to produce a Consensus document based on the revision of the criteria proposed by AIFA in light of the most recent literature and experts' agreement.This Consensus tries to detail which patients actually have the risk to develop severe disease, analyzing the most common comorbidities in children, in order to detail the indications for mAbs administration and to guide the clinicians in identifying eligible patients

Relazione tecnica sulle attività della campagna oceanografica ANCHEVA 2018

La gestione sostenibile delle risorse alieutiche è un tema sempre più rilevante nel contesto della pesca mondiale, anche a causa del progressivo aumento della capacità e dello sforzo di pesca. I prelievi eccessivi hanno portato all’impoverimento delle risorse ittiche determinando effetti negativi, diretti e indiretti, sia in termini ecologici che socio-economici. Le alterazioni si possono evidenziare sia a livello di comunità che a livello di funzionalità ecosistemica.Per tali ragioni si sono rese necessarie misure di gestione sostenibile delle risorse ittiche che preservino la capacità degli ecosistemi di fornire beni e servizi alle generazioni presenti e future. In tale contesto da alcuni anni, nel mar Mediterraneo, vengono condotti con regolarità survey acustici per la valutazione dell’abbondanza e della distribuzione della biomassa pelagica degli stock di acciughe (Engraulis encrasicolus), sardine (Sardina pilchardus) e suri (Trachurus trachurus) con l’utilizzo di strumentazione elettroacustica

Relazione tecnica sulle attività della campagna oceanografica EVATIR 2018

La crescente pressione antropica sull’ambiente naturale ha determinato una sempre maggiore attenzione della comunità scientifica sull’importanza degli effetti di disturbo in particolare della pesca su comunità biologiche ed ecosistemi. Il sovra sfruttamento, ovvero l’utilizzo oltre i limiti sostenibili, compromette infatti la capacità degli ecosistemi di continuare a fornire servizi all’uomo. Nel mondo della pesca e nel contesto normativo che la riguarda, si sta ponendo sempre maggiore attenzione alla redazione di appositi piani di gestione sostenibile della pesca, che favoriscano la preservazione, che prevengano il collasso degli stock e che riconducano la pesca entro condizioni di sostenibilità

Type II Endoleak Involving an Accessory Renal Artery and the Inferior Mesenteric Artery

International audienc