Continuous infusion of ceftazidime in critically ill patients undergoing continuous venovenous haemodiafiltration: pharmacokinetic evaluation and dose recommendation

INTRODUCTION: In seriously infected patients with acute renal failure and who require continuous renal replacement therapy, data on continuous infusion of ceftazidime are lacking. Here we analyzed the pharmacokinetics of ceftazidime administered by continuous infusion in critically ill patients during continuous venovenous haemodiafiltration (CVVHDF) in order to identify the optimal dosage in this setting. METHOD: Seven critically ill patients were prospectively enrolled in the study. CVVHDF was performed using a 0.6 m(2 )AN69 high-flux membrane and with blood, dialysate and ultrafiltration flow rates of 150 ml/min, 1 l/hour and 1.5 l/hour, respectively. Based on a predicted haemodiafiltration clearance of 32.5 ml/min, all patients received a 2 g loading dose of ceftazidime, followed by a 3 g/day continuous infusion for 72 hours. Serum samples were collected at 0, 3, 15 and 30 minutes and at 1, 2, 4, 6, 8, 12, 24, 36, 48 and 72 hours; dialysate/ultrafiltrate samples were taken at 2, 8, 12, 24, 36 and 48 hours. Ceftazidime concentrations in serum and dialysate/ultrafiltrate were measured using high-performance liquid chromatography. RESULTS: The mean (± standard deviation) elimination half-life, volume of distribution, area under the concentration-time curve from time 0 to 72 hours, and total clearance of ceftazidime were 4 ± 1 hours, 19 ± 6 l, 2514 ± 212 mg/h per l, and 62 ± 5 ml/min, respectively. The mean serum ceftazidime steady-state concentration was 33.5 mg/l (range 28.8–36.3 mg/l). CVVHDF effectively removed continuously infused ceftazidime, with a sieving coefficient and haemodiafiltration clearance of 0.81 ± 0.11 and 33.6 ± 4 mg/l, respectively. CONCLUSION: We conclude that a dosing regimen of 3 g/day ceftazidime, by continuous infusion, following a 2 g loading dose, results in serum concentrations more than four times the minimum inhibitory concentration for all susceptible pathogens, and we recommend this regimen in critically ill patients undergoing CVVHDF

MRI Sequences Optimization for PET-MRI Use in Head and Neck Cancer

Le bilan d’imagerie des cancers des voies aérodigestives supérieures utilise l’imagerie par résonance magnétique (IRM) et l’imagerie de tomographie par émission de positons (TEP). La TEP-IRM réunit ces deux imageries et permettent (sic) d’envisager l’exploration multiparamétrique des cancers ORL. La mise en place d’un protocole d’imagerie TEP-IRM pose des questions d’instrumentation. Les objectifs étaient de : quantifier et corriger le phénomène d’entrée de coupe artériel sur les séquences IRM de perfusion /perméabilité ; mesurer la précision des cartographies de valeur des temps de relaxation T1 et mesurer le temps de relaxation T1 du cancer ORL ; calculer le taux de détection des nodules pulmonaires par la séquence IRM à temps d’écho zéro (ZTE) et évaluer la précision de la mesure de la taille des nodules pulmonaires ; Comparer les valeurs des indices de texture de la radiomique à 3 Tesla et 1,5 Tesla. L’étude du phénomène d’entrée de coupe et de sa correction a été effectuée avec un imageur 3 Tesla et un fantôme de flux puis chez l’homme. L’étude de la cartographie T1 a été effectuée avec un imageur 3 Tesla et des fantômes de calibration, la mesure du T1 du cancer ORL a été effectuée chez 10 patients. L’étude de la séquence ZTE a été effectué par deux lecteurs avec imageur 3 Tesla en comparaison de la tomodensitométrie (gold standard) chez 12 patients. L’étude des indices de texture a été effectuée avec des imageurs 3 Tesla et 1,5 Tesla et des fantômes faits « maison » avec un logiciel de texture en accès libre et chez 10 volontaires sains. La méthode IRM de présaturation du flux artériel carotidien corrige efficacement l’altération du signal de la fonction d’entrée artérielle liée au phénomène d’entrée de coupe. Son application permet d’envisager de réaliser des acquisitions IRM de perfusion / perméabilité répondant aux recommandations des sociétés savantes en terme de résolution temporelle (inférieure à 5 secondes) tout en étant adaptée à l’anatomie ORL et à la combinaison des imagerie paramétriques. La valeur du temps de relaxation T1 des carcinomes épidermoïdes des VADS est calculée à 1314,5 ms (± 246,1). La réalisation d’une cartographie T1 nécessite la calibration des séquences cliniques à l’aide d’un fantôme et de séquences IRM de référence. Le taux de détection des nodules pulmonaire par ZTE est des 53% (IC95% [48-58]), et de 85% (IC95% [78-92]) pour les nodules de plus de 9 mm. La corrélation entre la taille des nodules avec la séquence ZTE et la taille au scanner est excellente. Les voies d’amélioration de la séquence se portent sur l’augmentation de la résolution spatiale et l’optimisation du contrôle du mouvement respiratoire. Les valeurs des indices de texture en IRM varient avec l’intensité du champ magnétique (3 Tesla versus 1.5 Tesla). Ces résultats contribuent à l’élaboration d’un protocole d’acquisition d’image TEP-IRM en cancérologie ORL. Deux études cliniques loi Jardé 3 sont en cours et utilisent ces résultats. Ces études permettront d’évaluer les performances de l’appareil TEP-IRM et de la combinaison des imageries paramétriques IRM et TEP en carcinologie ORL, ceci avec un haut niveau de preuve histologique.The imaging workup for Head and Neck (ENT) cancers uses magnetic resonance imaging (MRI) and positron emission tomography (PET) imaging. PET-MRI combines these two modalities and makes it possible to consider multiparametric exploration of ENT cancers. The implementation of a PET-MRI imaging protocol raises instrumentation questions.OjectivesThe objectives were to: quantify and correct arterial flow-related enhancement on dynamic contrast-enhanced MRI ; measure the precision of the T1 relaxation times maps and measure the T1 relaxation time of ENT cancer ; calculate the lung nodules detection rate by the MRI zero echo time sequence (ZTE) and evaluate the accuracy of lung nodules size measurement ; compare radiomic features values for different magnetic field strength (3 Tesla versus 1.5 Tesla). The study of the arterial flow-related enhancement and its correction was carried out with a 3 Tesla imager and a flow apparatus, then in humans. The T1 mapping study was performed with a 3 Tesla imager and calibration phantoms, the T1 measurement of ENT cancer was performed in 10 patients. The study of the ZTE sequence was performed by two readers with a 3 Tesla imager in comparison with the computed tomography (CTscan, gold standard) in 12 patients. The study of texture indices was performed with 3 Tesla and 1.5 Tesla imagers and “homemade phantoms”, with an open access texture software and then in 10 healthy volunteers. The MRI saturation method of the carotid arterial flow effectively corrects the alteration of the signal of the arterial input function related to the flow-related enhancement. Its application makes it possible to consider performing MRI perfusion / permeability acquisitions that meet the recommendations of learned societies in terms of temporal resolution (less than 5 seconds) while being adapted to ENT anatomy and to the combination of parametric imaging. The value of the relaxation time T1 of squamous cell carcinoma of the VADS is calculated at 1314.5 ms (± 246.1). Performing T1 mapping requires calibration of clinical MRI sequences using a phantom and reference MRI sequences.The detection rate of pulmonary nodules by ZTE is 53% (CI95% [48-58]), and 85% (CI95% [78-92]) for nodules of size more than 9 mm. The correlation between the size of the nodules with the ZTE sequence and the size on the CTscan is excellent. Areas for improvement of the sequence may focus on increasing spatial resolution and optimizing control of respiratory movement.The values of the texture indices in MRI vary with the intensity of the magnetic field (3 Tesla versus 1.5 Tesla). These results contribute to the development of a protocol for acquiring PET-MRI images in ENT oncology. Two clinical studies are in progress using these results. These studies will make it possible to evaluate the performance of the PET-MRI and of the combination of parametric MRI and PET imaging in ENT cancer, with a high level of histological evidence

Optimisation des séquences IRM et positionnement en carcinologie cervico-faciale de la TEP-IRM

The imaging workup for Head and Neck (ENT) cancers uses magnetic resonance imaging (MRI) and positron emission tomography (PET) imaging. PET-MRI combines these two modalities and makes it possible to consider multiparametric exploration of ENT cancers. The implementation of a PET-MRI imaging protocol raises instrumentation questions.OjectivesThe objectives were to: quantify and correct arterial flow-related enhancement on dynamic contrast-enhanced MRI ; measure the precision of the T1 relaxation times maps and measure the T1 relaxation time of ENT cancer ; calculate the lung nodules detection rate by the MRI zero echo time sequence (ZTE) and evaluate the accuracy of lung nodules size measurement ; compare radiomic features values for different magnetic field strength (3 Tesla versus 1.5 Tesla). The study of the arterial flow-related enhancement and its correction was carried out with a 3 Tesla imager and a flow apparatus, then in humans. The T1 mapping study was performed with a 3 Tesla imager and calibration phantoms, the T1 measurement of ENT cancer was performed in 10 patients. The study of the ZTE sequence was performed by two readers with a 3 Tesla imager in comparison with the computed tomography (CTscan, gold standard) in 12 patients. The study of texture indices was performed with 3 Tesla and 1.5 Tesla imagers and “homemade phantoms”, with an open access texture software and then in 10 healthy volunteers. The MRI saturation method of the carotid arterial flow effectively corrects the alteration of the signal of the arterial input function related to the flow-related enhancement. Its application makes it possible to consider performing MRI perfusion / permeability acquisitions that meet the recommendations of learned societies in terms of temporal resolution (less than 5 seconds) while being adapted to ENT anatomy and to the combination of parametric imaging. The value of the relaxation time T1 of squamous cell carcinoma of the VADS is calculated at 1314.5 ms (± 246.1). Performing T1 mapping requires calibration of clinical MRI sequences using a phantom and reference MRI sequences.The detection rate of pulmonary nodules by ZTE is 53% (CI95% [48-58]), and 85% (CI95% [78-92]) for nodules of size more than 9 mm. The correlation between the size of the nodules with the ZTE sequence and the size on the CTscan is excellent. Areas for improvement of the sequence may focus on increasing spatial resolution and optimizing control of respiratory movement.The values of the texture indices in MRI vary with the intensity of the magnetic field (3 Tesla versus 1.5 Tesla). These results contribute to the development of a protocol for acquiring PET-MRI images in ENT oncology. Two clinical studies are in progress using these results. These studies will make it possible to evaluate the performance of the PET-MRI and of the combination of parametric MRI and PET imaging in ENT cancer, with a high level of histological evidence.Le bilan d’imagerie des cancers des voies aérodigestives supérieures utilise l’imagerie par résonance magnétique (IRM) et l’imagerie de tomographie par émission de positons (TEP). La TEP-IRM réunit ces deux imageries et permettent (sic) d’envisager l’exploration multiparamétrique des cancers ORL. La mise en place d’un protocole d’imagerie TEP-IRM pose des questions d’instrumentation. Les objectifs étaient de : quantifier et corriger le phénomène d’entrée de coupe artériel sur les séquences IRM de perfusion /perméabilité ; mesurer la précision des cartographies de valeur des temps de relaxation T1 et mesurer le temps de relaxation T1 du cancer ORL ; calculer le taux de détection des nodules pulmonaires par la séquence IRM à temps d’écho zéro (ZTE) et évaluer la précision de la mesure de la taille des nodules pulmonaires ; Comparer les valeurs des indices de texture de la radiomique à 3 Tesla et 1,5 Tesla. L’étude du phénomène d’entrée de coupe et de sa correction a été effectuée avec un imageur 3 Tesla et un fantôme de flux puis chez l’homme. L’étude de la cartographie T1 a été effectuée avec un imageur 3 Tesla et des fantômes de calibration, la mesure du T1 du cancer ORL a été effectuée chez 10 patients. L’étude de la séquence ZTE a été effectué par deux lecteurs avec imageur 3 Tesla en comparaison de la tomodensitométrie (gold standard) chez 12 patients. L’étude des indices de texture a été effectuée avec des imageurs 3 Tesla et 1,5 Tesla et des fantômes faits « maison » avec un logiciel de texture en accès libre et chez 10 volontaires sains. La méthode IRM de présaturation du flux artériel carotidien corrige efficacement l’altération du signal de la fonction d’entrée artérielle liée au phénomène d’entrée de coupe. Son application permet d’envisager de réaliser des acquisitions IRM de perfusion / perméabilité répondant aux recommandations des sociétés savantes en terme de résolution temporelle (inférieure à 5 secondes) tout en étant adaptée à l’anatomie ORL et à la combinaison des imagerie paramétriques. La valeur du temps de relaxation T1 des carcinomes épidermoïdes des VADS est calculée à 1314,5 ms (± 246,1). La réalisation d’une cartographie T1 nécessite la calibration des séquences cliniques à l’aide d’un fantôme et de séquences IRM de référence. Le taux de détection des nodules pulmonaire par ZTE est des 53% (IC95% [48-58]), et de 85% (IC95% [78-92]) pour les nodules de plus de 9 mm. La corrélation entre la taille des nodules avec la séquence ZTE et la taille au scanner est excellente. Les voies d’amélioration de la séquence se portent sur l’augmentation de la résolution spatiale et l’optimisation du contrôle du mouvement respiratoire. Les valeurs des indices de texture en IRM varient avec l’intensité du champ magnétique (3 Tesla versus 1.5 Tesla). Ces résultats contribuent à l’élaboration d’un protocole d’acquisition d’image TEP-IRM en cancérologie ORL. Deux études cliniques loi Jardé 3 sont en cours et utilisent ces résultats. Ces études permettront d’évaluer les performances de l’appareil TEP-IRM et de la combinaison des imageries paramétriques IRM et TEP en carcinologie ORL, ceci avec un haut niveau de preuve histologique

Computing approximate geodesics and minimal surfaces using watershed and graph cuts

Geodesics and minimal surfaces are widely used for medical image segmentation. At least two different approaches are used to compute such segmentations. First, geodesic active contours use differential geometry to compute optimal contours minimizing a given Riemannian metric. Second, Boykov and Kolmogorov have proposed a method based on integral geometry to compute similar contours using a graph representation of the image and combinatorial optimization. In this paper we present a technique to compute approximate geodesics and minimal surfaces using a low-level segmentation and graph-cuts optimization. Our approach speeds-up the computation of minimal surfaces when a low-level segmentation is available

Interactive liver tumor segmentation using graph cuts and watershed

Abstract. We present in this paper an application of minimal surfaces and Markov random fields to the segmentation of liver tumors. The originality of the work consists in applying these models to the region adjacency graph of a watershed transform. We detail the assumptions and the approximations introduced in these models by using a region graph instead of a pixel graph. This strategy leads to an interactive method used to delineate tumors in 3D CT images. We detail our strategy to achieve relevant segmentations of these structures and compare our results to hand made segmentations done by experienced radiologists. This paper summarizes our participation to the MICCAI 2008 3 workshop called: ”3D segmentation in the clinic: A Grand Challenge II”.

Illustrissimo abbati Nicolao de Saulx de Tavanes, cum theses philosophicas propugnaret... in Collegio Mazarinaeo, 8°kal. julii... 1708. [Signé : Franciscus Bidault.]

Avec mode text

Overview of SERMA’s Graphical User Interfaces for Lattice Transport Calculations

This article presents an overview of the graphical user interfaces (GUIs) developed at CEA/SERMA (Service d’Études des Réacteurs et de Mathématiques Appliquées) in Saclay, France, which have been used for over forty years by engineers and scientists to build geometries and meshes for general-purpose lattice transport calculations (neutrons and photons). Several applications make use of these calculations, from fuel assembly to full core design, criticality and safety, needing consistency check of the geometry and input properties before starting any lattice calculation. The software pattern design of the GUIs is briefly discussed, showing also the rationale behind the two interfaces for the construction of the geometries for simple fuel assemblies and complex motifs including the reflector (colorsets). The new GUI, ALAMOS, specifically developed for APOLLO3® with a Python Application Programming Interface (API), is here presented as the successor of Silène, which was the first GUI released in the 1990s to serve APOLLO2 calculations. The considerable experience gained by Silène over the years with plenty of various applications has provided a crucial support for the development of ALAMOS

Overview of SERMA’s Graphical User Interfaces for Lattice Transport Calculations

This article presents an overview of the graphical user interfaces (GUIs) developed at CEA/SERMA (Service d’Études des Réacteurs et de Mathématiques Appliquées) in Saclay, France, which have been used for over forty years by engineers and scientists to build geometries and meshes for general-purpose lattice transport calculations (neutrons and photons). Several applications make use of these calculations, from fuel assembly to full core design, criticality and safety, needing consistency check of the geometry and input properties before starting any lattice calculation. The software pattern design of the GUIs is briefly discussed, showing also the rationale behind the two interfaces for the construction of the geometries for simple fuel assemblies and complex motifs including the reflector (colorsets). The new GUI, ALAMOS, specifically developed for APOLLO3® with a Python Application Programming Interface (API), is here presented as the successor of Silène, which was the first GUI released in the 1990s to serve APOLLO2 calculations. The considerable experience gained by Silène over the years with plenty of various applications has provided a crucial support for the development of ALAMOS

CT-scan prediction of thyroid cartilage invasion for early laryngeal squamous cell carcinoma

International audienc