A new overhang constraint for topology optimization of self-supporting structures in additive manufacturing

This work falls within the scope of computer-aided optimal design, and aims to integrate the topology optimization procedures and recent additive manufacturing technologies (AM). The elimination of scaffold supports at the topology optimization stage has been recognized and pursued by many authors recently. The present paper focuses on implementing a novel and specific overhang constraint that is introduced inside the topology optimization problem formulation along with the regular volume constraint. The proposed procedure joins the design and manufacturing processes into a integrated workflow where any component can directly be manufactured with no requirement of any sacrificial support material right after the topology optimization process. The overhang constraint presented in this work is defined by the maximum allowable inclination angle, where the inclination of any member is computed by the Smallest Univalue Segment Assimilating Nucleus (SUSAN), an edge detection algorithm developed in the field of image analysis and processing. Numerical results on some benchmark examples, along with the numerical performances of the proposed method, are introduced to demonstrate the capacities of the presented approach.This work was supported by The European Regional Development Fund (ERDF-FEDER) and the Ministry of Education and Science in Spain through the DPI2015-64863-R project (MINECO/FEDER-UE). The authors also wish to thank the Basque Government for financial assistance through IT919-16

Albiglutide and cardiovascular outcomes in patients with type 2 diabetes and cardiovascular disease (Harmony Outcomes): a double-blind, randomised placebo-controlled trial

Background: Glucagon-like peptide 1 receptor agonists differ in chemical structure, duration of action, and in their effects on clinical outcomes. The cardiovascular effects of once-weekly albiglutide in type 2 diabetes are unknown. We aimed to determine the safety and efficacy of albiglutide in preventing cardiovascular death, myocardial infarction, or stroke. Methods: We did a double-blind, randomised, placebo-controlled trial in 610 sites across 28 countries. We randomly assigned patients aged 40 years and older with type 2 diabetes and cardiovascular disease (at a 1:1 ratio) to groups that either received a subcutaneous injection of albiglutide (30–50 mg, based on glycaemic response and tolerability) or of a matched volume of placebo once a week, in addition to their standard care. Investigators used an interactive voice or web response system to obtain treatment assignment, and patients and all study investigators were masked to their treatment allocation. We hypothesised that albiglutide would be non-inferior to placebo for the primary outcome of the first occurrence of cardiovascular death, myocardial infarction, or stroke, which was assessed in the intention-to-treat population. If non-inferiority was confirmed by an upper limit of the 95% CI for a hazard ratio of less than 1·30, closed testing for superiority was prespecified. This study is registered with ClinicalTrials.gov, number NCT02465515. Findings: Patients were screened between July 1, 2015, and Nov 24, 2016. 10 793 patients were screened and 9463 participants were enrolled and randomly assigned to groups: 4731 patients were assigned to receive albiglutide and 4732 patients to receive placebo. On Nov 8, 2017, it was determined that 611 primary endpoints and a median follow-up of at least 1·5 years had accrued, and participants returned for a final visit and discontinuation from study treatment; the last patient visit was on March 12, 2018. These 9463 patients, the intention-to-treat population, were evaluated for a median duration of 1·6 years and were assessed for the primary outcome. The primary composite outcome occurred in 338 (7%) of 4731 patients at an incidence rate of 4·6 events per 100 person-years in the albiglutide group and in 428 (9%) of 4732 patients at an incidence rate of 5·9 events per 100 person-years in the placebo group (hazard ratio 0·78, 95% CI 0·68–0·90), which indicated that albiglutide was superior to placebo (p<0·0001 for non-inferiority; p=0·0006 for superiority). The incidence of acute pancreatitis (ten patients in the albiglutide group and seven patients in the placebo group), pancreatic cancer (six patients in the albiglutide group and five patients in the placebo group), medullary thyroid carcinoma (zero patients in both groups), and other serious adverse events did not differ between the two groups. There were three (<1%) deaths in the placebo group that were assessed by investigators, who were masked to study drug assignment, to be treatment-related and two (<1%) deaths in the albiglutide group. Interpretation: In patients with type 2 diabetes and cardiovascular disease, albiglutide was superior to placebo with respect to major adverse cardiovascular events. Evidence-based glucagon-like peptide 1 receptor agonists should therefore be considered as part of a comprehensive strategy to reduce the risk of cardiovascular events in patients with type 2 diabetes. Funding: GlaxoSmithKline

Effet sur l'asynchronisme ventriculaire de l'injection intra coronaire de cellules souches de moelle osseuse dans l'infarctus (une étude ancillaire rétrospective de l essai BONAMI)

CAEN-BU Médecine pharmacie (141182102) / SudocSudocFranceF

Evaluation en tomographie par émission de positons de l'impact de la réadaptation cardiaque sur la fonction endothéliale coronaire chez le patient insuffisant cardiaque (résultats préliminaires de l'étude TEP-READ)

CAEN-BU Médecine pharmacie (141182102) / SudocSudocFranceF

Valeurs diagnostique et pronostique des tests non invasifs dans la détection de la maladie coronaire du greffon

La maladie coronaire du greffon ou rejet chronique est la première cause de décès après cinq ans de transplantation cardiaque. Son dépistage est fondamental, son diagnostic loin d'être aisé. Parmi les tests non invasifs, seule la valeur de l'échocardiographie sous dobutamine est documentée. Depuis la publication des études prouvant l'inefficacité de la scintigraphie myocardique de perfusion, l'analyse de la fonction myocardique par Gated-SPECT a permis d'améliorer les performances de l'examen. Le but de notre étude a été de tester la valeur diagnostique et pronostique des tests non invasifs, l'examen de référence pour déterminer la maladie coronaire du greffon étant la coronarographie. La sensibilité et la valeur prédictive négative de la scintigraphie myocardique sont respectivement de 80 et 71%, pour tous les types de lésions coronaires et de 91 et 93% pour la détection de sténoses supérieures ou égales à 50%. Lorsque la scintigraphie de perfusion et de fonction VG est couplée à l'échocardiographie sous dobutamine, la sensibilité et la valeur prédictive négative atteignent respectivement 86 et 85% pour la détection de tous les types de lésion et 100% pour les sténoses supérieures à 50%. L'association d'une scintigraphie myocardique et d'une échocardiographie sous dobutamine négatives permettrait donc d'éviter la réalisation d'une coronarographie chez des patients indemnes de maladie coronaire du greffon. L'étendue de l'ischémie est un facteur pronostique indépendant dans la survenue d'évènements cardiaques majeurs. L'hypocholestérolémie probable reflet d'un état inflammatoire chronique est un facteur pronostique indépendant de survenue de décès, de retransplantation et d'insuffisance cardiaque.ROUEN-BU Médecine-Pharmacie (765402102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Optimisation des paramètres d'acquisition et de reconstruction en tomoscintigraphie myocardique synchronisée à l'électrocardiogramme (gated SPECT)

Au cours de ce travail de thèse, nous avons exploré l'impact de paramètres d'acquisition et de reconstruction sur l'évaluation de la fonction ventriculaire gauche en gated SPECT. Des résultats significatifs ont été obtenus sur des populations sélectionnées, sur fantôme organomorphe, ou par simulation. Les conclusions peuvent être résumées ainsi : La fraction d'éjection ventriculaire gauche mesurée en gated SPECT est sous-estimée en comparaison à l'angioscintigraphie. Elle est dépendante de l'échantillonnage temporel à l'acquisition. L'augmentation de l'échantillonnage à 16 intervalles par cycle améliore significativement la corrélation et la concordance par rapport à l'angioscintigraphie. Lorsque l'on compare les influences du traceur (Tl-201 ou Tc-99m-sestamibi) et de l'échantillonnage temporel (8 ou 16 intervalles), ce dernier est de loin facteur le plus important. La détection du rayonnement diffusé lors de l'acquisition et sa correction par une méthode de déconvolution spectrale ont eu un impact significatif sur l'évaluation des volumes. Enfin, la séquence d'acquisition de l'imagerie (effort-repos ou repos-effort) ainsi que la présence d'anomalies de perfusion influencent significativement la mesure des volumes et de la fraction d'éjection. Concernant les paramètres de reconstruction, le type de filtre et de zoom à la reconstruction influencent de façon significative les mesures de volume, et donc le calcul de la fraction d'éjection. L'évaluation des volumes et le calcul de fraction d'éjection sont dépendants de la méthode de calcul utilisée (Stanford ou Cedars Sinai), cette différence incitant à utiliser le même logiciel lorsqu'il s'agit de suivre une population. Avec la méthode de Stanford, l'erreur de mesure des volumes augmente avec la taille de l'infarctus. Enfin, les paramètres de reconstruction qui favorisent la résolution spatiale et compensent les conséquences du rayonnement diffusé améliorent la mesure des volumes.In this work, we explored the impact of several acquisition and reconstruction parameters on the evaluation of left ventricular function using gated SPECT. Significant results were obtained in selected populations, and using anthropomorphic phantom or mathematical simulations. The main conclusions are as follows: Gated SPECT left ventricular ejection fraction was underestimated compared to planar radionuclide angiography, and depends on temporal sampling. Increasing temporal sampling to 16-interval gating provided a higher correlation and agreement compared to planar radionuclide angiography. When comparing the respective influences of radiotracers (Tl-201 or Tc-99m-sestamibi) and temporal sampling (8 vs. 16 bins), the latter had the most important effect. Scatter detection during the acquisition process, and its correction using a spectral deconvolution method had a significant impact on volume measurements. Finally, in a computer simulation using the MCAT phantom, we demonstrated that both the acquisition sequence of gated SPECT imaging (stress-rest vs. rest-stress) and perfusion abnormalities significantly influenced volumes and ejection fraction measurements. Regarding reconstruction parameters, filtering and zooming influenced volume assessment, and ejection fraction calculation. Using the Stanford method, the error in volume assessment was increased with myocardial infarction size. Actually, volume and ejection fraction evaluations were dependent on the 3-dimensional method used for assessment (Stanford vs. Cedars Sinai), leading to recommend to use the same method for serial patients evaluation. Finally, reconstruction parameters that favor spatial resolution or compensate for the consequences of scatter detection increased the accuracy of volume measurement.PARIS12-CRETEIL BU Multidisc. (940282102) / SudocSudocFranceF

Évaluation de l'asynchronisme intraventriculaire gauche en ventriculographie planaire isotopique et tomoscintigraphie myocardique de perfusion

CAEN-BU Médecine pharmacie (141182102) / SudocSudocFranceF

Effect of perfusion pattern and imaging sequence on gated perfusion SPECT evaluation of myocardial stunning.

International audienceThe aim of this study was to determine the effect of perfusion defect and imaging sequence on the evaluation of myocardial stunning with gated perfusion SPECT

Cardiac magnetic resonance demonstrates myocardial oedema in remote tissue early after reperfused myocardial infarction.

International audienceBACKGROUND: Cardiac magnetic resonance can detect myocardial oedema using myocardial transverse relaxation time (T2)-weighted sequences but quantitative data are lacking in patients evaluated early after acute myocardial infarction. AIM: To assess the spatial distribution of T2 in patients with recent acute myocardial infarction. METHODS: Twenty-four consecutive patients (mean age 60+/-11 years) with acute myocardial infarction (anterior, n=12; inferior, n=12) were evaluated prospectively. T2 was determined using a series of breath-hold T2-weighted segmented half-Fourier turbo-spin echo sequences. No-reflow was defined as the association of early hypoenhancement and delayed enhancement in an akinetic region after a bolus injection of DOTA-Gd (0.2 mmol/kg). RESULTS: No-reflow was present in 13 (54%) patients and absent in 11 (46%) patients. Mean T2 was increased in the infarct region (84.9+/-23.7 ms) compared with in the remote myocardium (62.8+/-10.3 ms, p=0.0001) and in control subjects (55.7+/-4.6 ms, p<0.0001), but also in the remote myocardium compared with control subjects (p<0.02). In patients with no-reflow, T2 was further increased within the infarcted subendocardium compared with in patients without no-reflow (97.9+/-24.8 ms vs 76.3+/-24.7 ms, p<0.03). Peak troponin correlated with T2 (r=0.47, p<0.02) and was higher in patients with no-reflow (297.9+/-249.7 microg/L) than in patients without no-reflow (42.4+/-43.1 microg/L, p=0.003). CONCLUSION: T2 was lengthened in both infarcted and remote myocardium and was influenced by the occurrence of no-reflow