Publications by authors named "COURVOISIER S"

Purpose: Proton magnetic resonance spectroscopic imaging ( -MRSI) provides noninvasive spectral-spatial mapping of metabolism. However, long-standing problems in whole-brain -MRSI are spectral overlap of metabolite peaks with large lipid signal from scalp, and overwhelming water signal that distorts spectra. Fast and effective methods are needed for high-resolution -MRSI to accurately remove lipid and water signals while preserving the metabolite signal.

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Objectives: Phosphorus-31 magnetic resonance spectroscopic imaging (P-MRSI) is a non-invasive tool for assessing cellular high-energy metabolism in-vivo. However, its acquisition suffers from a low sensitivity, which necessitates large voxel sizes or multiple averages to achieve an acceptable signal-to-noise ratio (SNR), resulting in long scan times.

Materials And Methods: To overcome these limitations, we propose an acquisition and reconstruction scheme for FID-MRSI sequences.

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A novel method for fast and high-resolution metabolic imaging, called ECcentric Circle ENcoding TRajectorIes for Compressed sensing (ECCENTRIC), has been developed at 7 Tesla MRI. ECCENTRIC is a non-Cartesian spatial-spectral encoding method designed to accelerate magnetic resonance spectroscopic imaging (MRSI) with high signal-to-noise at ultra-high field. The approach provides flexible and random sampling of the Fourier space without temporal interleaving to improve spatial response function and spectral quality.

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MRI, a widespread non-invasive medical imaging modality, is highly sensitive to patient motion. Despite many attempts over the years, motion correction remains a difficult problem and there is no general method applicable to all situations. We propose a retrospective method for motion estimation and correction to tackle the problem of in-plane rigid-body motion, apt for classical 2D Spin-Echo scans of the brain, which are regularly used in clinical practice.

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(1) Background: Various cutaneous adverse drug reactions (ADRs) are observed with the implementation of mRNA COVID-19 vaccines. To gain insight into the clinicopathologic features, we analyzed the correlation of histological and clinical data in 48 patients with these ADRs. (2) Methods: Single-center retrospective study in patients with ADRs after mRNA COVID-19 vaccination (mRNA-1273 and BNT162b2 vaccines).

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A novel method for fast and high-resolution metabolic imaging, called ECcentric Circle ENcoding TRajectorIes for Compressed sensing (ECCENTRIC), has been developed and implemented at 7 Tesla MRI. ECCENTRIC is a non-Cartesian spatial-spectral encoding method optimized to accelerate magnetic resonance spectroscopic imaging (MRSI) with high signal-to-noise at ultra-high field. The approach provides flexible and random sampling without temporal interleaving to improve spatial response function and spectral quality.

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Preterm birth disrupts important neurodevelopmental processes occurring from mid-fetal to term-age. Musicotherapy, by enriching infants' sensory input, might enhance brain maturation during this critical period of activity-dependent plasticity. To study the impact of music on preterm infants' brain structural changes, we recruited 54 very preterm infants randomized to receive or not a daily music intervention, that have undergone a longitudinal multi-shell diffusion MRI acquisition, before the intervention (at 33 weeks' gestational age) and after it (at term-equivalent-age).

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Purpose: We have introduced an artificial intelligence framework, 31P-SPAWNN, in order to fully analyze phosphorus-31 ( P) magnetic resonance spectra. The flexibility and speed of the technique rival traditional least-square fitting methods, with the performance of the two approaches, are compared in this work.

Theory And Methods: Convolutional neural network architectures have been proposed for the analysis and quantification of P-spectroscopy.

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MRI is a non-invasive medical imaging modality that is sensitive to patient motion, which constitutes a major limitation in most clinical applications. Solutions may arise from the reduction of acquisition times or from motion-correction techniques, either prospective or retrospective. Benchmarking the latter methods requires labeled motion-corrupted datasets, which are uncommon.

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There is a growing interest in the neuroscience community to map the distribution of brain metabolites in vivo. Magnetic resonance spectroscopic imaging (MRSI) is often limited by either a poor spatial resolution and/or a long acquisition time, which severely restricts its applications for clinical and research purposes. Building on a recently developed technique of acquisition-reconstruction for 2D MRSI, we combined a fast Cartesian H-FID-MRSI acquisition sequence, compressed-sensing acceleration, and low-rank total-generalized-variation constrained reconstruction to produce 3D high-resolution whole-brain MRSI with a significant acquisition time reduction.

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Background And Purpose: Super-resolutionreconstruction (SRR) can be used to reconstruct 3-dimensional (3D) high-resolution (HR) volume from several 2-dimensional (2D) low-resolution (LR) stacks of MRI slices. The purpose is to compare lengthy 2D T2-weighted HR image acquisition of neonatal subjects with 3D SRR from several LR stacks in terms of image quality for clinical and morphometric assessments.

Methods: LR brain images were acquired from neonatal subjects to reconstruct isotropic 3D HR volumes by using SRR algorithm.

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Article Synopsis
  • COGERIA is a collaborative program in Geneva focused on enhancing care for frail elderly individuals through improved coordination among health and social services.
  • Launched in May 2019, it involves over 283 beneficiaries and 152 primary care physicians, working closely with home healthcare providers in the Servette and Meyrin regions.
  • Preliminary data indicates a potential reduction in hospitalizations and high satisfaction levels among both beneficiaries and program partners.
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Purpose: Epitomizing the advantages of ultra short echo time and no chemical shift displacement error, high-resolution-free induction decay magnetic resonance spectroscopic imaging (FID-MRSI) sequences have proven to be highly effective in providing unbiased characterizations of metabolite distributions. However, its merits are often overshadowed in high-resolution settings by reduced signal-to-noise ratios resulting from the smaller voxel volumes procured by extensive phase encoding and the related acquisition times.

Methods: To address these limitations, we here propose an acquisition and reconstruction scheme that offers both implicit dataset denoising and acquisition acceleration.

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Improving the efficiency, cell survival, and throughput of methods to modify and control the genetic expression of cells is of great benefit to biology and medicine. We investigate, both computationally and experimentally, a nanostructured substrate made of tipless pyramids for plasmonic-induced transfection. By optimizing the geometrical parameters for an excitation wavelength of 800 nm, we demonstrate a 100-fold intensity enhancement of the electric near field at the cell-substrate contact area, while the low absorption typical for gold is maintained.

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Unlabelled: The HPA-15 platelet (PLT) group was recently described. Severe neonatal thrombocytopenia due to alloimmunization by HPA-15b has very rarely been observed. A 22-year-old mother, gravida 1/para 1, gave birth to a male infant who presented with a severe thrombocytopenia, the PLT count recorded to be 3 x10(9)/L.

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Intestinal perforations in preterm newborn are characterized with high morbidity and mortality rates. They often are associated with necrotizing enterocolitis and seldom correspond to idiopathic spontaneous intestinal perforation. Perforations upstream of an intestinal organic obstruction (atresia), or of a functionnal obstruction (meconium-ileus, Hirschsprung disease) have been considered to be rare in preterm newborns.

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The 2 patients presented here showed the typical signs of hypocomplementemic urticarial vasculitis syndrome (HUVS). During follow-up, there was an inverse correlation between anti-C1q autoantibody titer and C1q antigen concentration in serum in both patients over a period of 2 years. The first patient had nephritis characterized by immune deposits in glomeruli and around the tubules.

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Objectives: (i) To investigate whether there is a difference in the prevalence of seborrheic dermatitis (SD) between homo- or bisexual HIV-infected patients and HIV-infected intravenous drug users, (ii) to study whether the initial CD4 T cell count at the first positive HIV test is of any significance for the prevalence of SD and furthermore to analyze whether (iii) antiretroviral treatment influences the prevalence and time course of SD.

Patients And Methods: Since 1992 we have been following, within the scope of the Swiss HIV Cohort Study, a group of individuals with proven HIV infection. In this study all HIV-infected patients belonging either to the risk group of homo- or bisexuals or that of intravenous drug users were included for further analysis.

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Background: True allergic reactions to iodinated radiocontrast media are rare, and only a few well-documented cases of delayed-type hypersensitivity reactions caused by contrast media have been described.

Methods: We report a 61-year-old patient in whom percutaneous transluminal coronary angioplasty (PTCA) was performed with iopamidol, a nonionic contrast medium. Seven days later, the patient developed generalized maculopapular exanthema.

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