Imaging of X-Ray-Excited Emissions from Quantum Dots and Biological Tissue in Whole Mouse

© The Author(s) 2019. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Optical imaging in clinical and preclinical settings can provide a wealth of biological information, particularly when coupled with targetted nanoparticles, but optical scattering and absorption limit the depth and resolution in both animal and human subjects. Two new hybrid approaches are presented, using the penetrating power of X-rays to increase the depth of optical imaging. Foremost, we demonstrate the excitation by X-rays of quantum-dots (QD) emitting in the near-infrared (NIR), using a clinical X-ray system to map the distribution of QDs at depth in whole mouse. We elicit a clear, spatially-resolved NIR signal from deep organs (brain, liver and kidney) with short (1 second) exposures and tolerable radiation doses that will permit future in vivo applications. Furthermore, X-ray-excited endogenous emission is also detected from whole mouse. The use of keV X-rays to excite emission from QDs and tissue represent novel biomedical imaging technologies, and exploit emerging QDs as optical probes for spatial-temporal molecular imaging at greater depth than previously possible.Peer reviewe

Limited-angle x-ray luminescence tomography: methodology and feasibility study

Abstract X-ray luminescence tomography (XLT) has recently been proposed as a new imaging modality for biological imaging applications. This modality utilizes phosphor nanoparticles which luminesce near-infrared light when excited by x-ray photons. The advantages of this modality are that it uniquely combines the high sensitivity of radioluminescent nanoparticles and the high spatial localization of collimated x-ray beams. Currently, XLT has been demonstrated using x-ray spatial encoding to resolve the imaging volume. However, there are applications where the x-ray excitation may be limited by geometry, where increased temporal resolution is desired, or where a lower dose is mandatory. This paper extends the utility of XLT to meet these requirements by incorporating a photon propagation model into the reconstruction algorithm in an x-ray limited-angle (LA) geometry. This enables such applications as image-guided surgery, where the ability to resolve lesions at depths of several centimeters can be the key to successful resection. The hybrid x-ray/diffuse optical model is first formulated and then demonstrated in a breast-sized phantom, simulating a breast lumpectomy geometry. Both numerical and experimental phantoms are tested, with lesion-simulating objects of various sizes and depths. Results show localization accuracy with median error of 2.2 mm, or 4% of object depth, for small 2-14 mm diameter lesions positioned from 1 to 4.5 cm in depth. This compares favorably with fluorescence optical imaging, which is not able to resolve such small objects at this depth. The recovered lesion size has lower size bias in the x-ray excitation direction than the optical direction, which is expected due to the increased optical scatter. However, the technique is shown to be quite invariant in recovered size with respect to depth, as the standard deviation is less than 2.5 mm. Sensitivity is a function of dose; radiological doses are found to provide sufficient recovery for μg ml −1 concentrations, while therapy dosages provide recovery for ng ml depth for a 5 mm object, and within 5.2% of the depth for a 10 mm object. Object-size median error is within 2.3% and 2% for the 5 and 10 mm objects, respectively. For shallow-to-medium depth applications where optical and radio-emission imaging modalities are not ideal, such as in intra-operative procedures, LAXLT may be a useful tool to detect molecular signatures of disease

Massively parallelizable list-mode reconstruction using a Monte Carlo-based elliptical Gaussian model

Purpose: A fully three-dimensional (3D) massively parallelizable list-mode ordered-subsets expectation-maximization (LM-OSEM) reconstruction algorithm has been developed for high-resolution PET cameras. System response probabilities are calculated online from a set of parameters derived from Monte Carlo simulations. The shape of a system response for a given line of response (LOR) has been shown to be asymmetrical around the LOR. This work has been focused on the development of efficient region-search techniques to sample the system response probabilities, which are suitable for asymmetric kernel models, including elliptical Gaussian models that allow for high accuracy and high parallelization efficiency. The novel region-search scheme using variable kernel models is applied in the proposed PET reconstruction algorithm...This work was partially supported by Spain’s Ministry of Science and Innovation through CDTI’s CENIT program (AMIT project) and INNPACTO (PRECISION project), Instituto de Salud Carlos III (PI09/91058 and PI09/91065), and Project Nos. TEC2010-21619-C04-03 and TEC2011-28972- C02-02, Comunidad de Madrid (ARTEMIS S2009/DPI- 1802), and the European Regional Development Funds (FEDER). CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008–2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions, and finance by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.Publicad

Facile Synthesis of Amine-Functionalized Eu3+-Doped La(OH)3 Nanophosphors for Bioimaging

Here, we report a straightforward synthesis process to produce colloidal Eu3+-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)3:Eu3+ NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (λex = 280 nm). The red emission, due to 5D0 → 7F1 and 5D0 → 7F2 transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)3:Eu3+ NPs possess the potential to serve as a luminescent bioimaging probe

A Randomized Trial of Convalescent Plasma in Covid-19 Severe Pneumonia

BACKGROUND:Convalescent plasma is frequently administered to patients with Covid-19 and hasbeen reported, largely on the basis of observational data, to improve clinical outcomes.Minimal data are available from adequately powered randomized, controlled trials. METHODS:We randomly assigned hospitalized adult patients with severe Covid-19 pneumoniain a 2:1 ratio to receive convalescent plasma or placebo. The primary outcome wasthe patient?s clinical status 30 days after the intervention, as measured on a six-pointordinal scale ranging from total recovery to death. RESULTS:A total of 228 patients were assigned to receive convalescent plasma and 105 toreceive placebo. The median time from the onset of symptoms to enrollment inthe trial was 8 days (interquartile range, 5 to 10), and hypoxemia was the mostfrequent severity criterion for enrollment. The infused convalescent plasma had amedian titer of 1:3200 of total SARS-CoV-2 antibodies (interquartile range, 1:800 to1:3200]. No patients were lost to follow-up. At day 30 day, no significant differencewas noted between the convalescent plasma group and the placebo group in thedistribution of clinical outcomes according to the ordinal scale (odds ratio, 0.83(95% confidence interval [CI], 0.52 to 1.35; P=0.46). Overall mortality was 10.96%in the convalescent plasma group and 11.43% in the placebo group, for a risk difference of −0.46 percentage points (95% CI, −7.8 to 6.8). Total SARS-CoV-2 antibodytiters tended to be higher in the convalescent plasma group at day 2 after the intervention. Adverse events and serious adverse events were similar in the two groups. CONCLUSIONS:no significant differences were observed in clinical status or overall mortality between patients treated with convalescent plasma and those who received placebo.(PlasmAr ClinicalTrials.gov number, NCT04383535.)Fil: Simonovich, Ventura A.. Hospital Italiano. Departamento de Medicina. Servicio de Clinica Medica.; ArgentinaFil: Burgos Pratx, Leandro D.. Hospital Italiano. Departamento de Medicina. Servicio de Clinica Medica.; ArgentinaFil: Scibona, Paula. Hospital Italiano. Departamento de Medicina. Servicio de Clinica Medica.; ArgentinaFil: Beruto, Maria Valeria. No especifíca;Fil: Vallone, Miguel Gabriel. No especifíca;Fil: Vázquez, C.. No especifíca;Fil: Savoy, N.. No especifíca;Fil: Giunta, Diego Hernan. No especifíca;Fil: Pérez, L.G.. No especifíca;Fil: Sánchez, M.L.. No especifíca;Fil: Gamarnik, Andrea Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ojeda, D.S.. No especifíca;Fil: Santoro, D.M.. No especifíca;Fil: Camino, P. J.. No especifíca;Fil: Antelo, S.. No especifíca;Fil: Rainero, K.. No especifíca;Fil: Vidiella, G. P.. No especifíca;Fil: Miyazaki, E. A.. No especifíca;Fil: Cornistein, W.. No especifíca;Fil: Trabadelo, O. A.. No especifíca;Fil: Ross, F. M.. No especifíca;Fil: Spotti, M.. No especifíca;Fil: Funtowicz, G.. No especifíca;Fil: Scordo, W. E.. No especifíca;Fil: Losso, M. H.. No especifíca;Fil: Ferniot, I.. No especifíca;Fil: Pardo, P. E.. No especifíca;Fil: Rodriguez, E.. No especifíca;Fil: Rucci, P.. No especifíca;Fil: Pasquali, J.. No especifíca;Fil: Fuentes, N. A.. No especifíca;Fil: Esperatti, M.. No especifíca;Fil: Speroni, G. A.. No especifíca;Fil: Nannini, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Inmunología Clinica y Experimental de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Instituto de Inmunología Clinica y Experimental de Rosario; ArgentinaFil: Matteaccio, A.. No especifíca;Fil: Michelangelo, H.G.. No especifíca;Fil: Follmann, D.. No especifíca;Fil: Lane, H. Clifford. No especifíca;Fil: Belloso, Waldo Horacio. Hospital Italiano. Departamento de Medicina. Servicio de Clinica Medica.; Argentin

Hybrid x-ray∕optical luminescence imaging: Characterization of experimental conditions

Purpose: The feasibility of x-ray luminescence imaging is investigated using a dual-modality imaging system that merges x-ray and optical imaging. This modality utilizes x-ray activated nanophosphors that luminesce when excited by ionizing photons. By doping phosphors with lanthanides, which emit light in the visible and near infrared range, the luminescence is suitable for biological applications. This study examines practical aspects of this new modality including phosphor concentration, light emission linearity, detector damage, and spectral emission characteristics. Finally, the contrast produced by these phosphors is compared to that of x-ray fluoroscopy