ABSTRACT
PURPOSE: Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) is an accepted method to evaluate tumor perfusion and permeability and anti-vascular cancer therapies. However, there is no consensus on the vascular input function estimation method, which is critical to kinetic modeling and K trans estimation. This work proposes a response-derived input function (RDIF) estimated from the response of the tumor, modeled as a linear, time-invariant (LTI) system. PROCEDURES: In an LTI system, an unknown input can be estimated from the system response. If applied to DCE MRI, this method would eliminate need of distal image-derived inputs, model inputs, or reference regions. The RDIF method first determines each tumor pixel's best-fit input function, and then combines the individual fits into a single input function for the entire tumor. The method was tested with simulations and a xenograft study with anti-vascular drug treatment. RESULTS: Simulations showed successful estimation of input function expected values and good performance in the presence of noise. In vivo, significant reductions in K trans and AUC occurred 2 days following anti-delta-like ligand 4 treatment. The in vivo study results yielded K trans consistent with published data in xenograft models. CONCLUSION: The RDIF method for DCE analysis offers an alternative, easy-to-implement method for estimating the input function in tumors. The method assumes that during the DCE experiment, the changes observed by MRI result solely from vascular perfusion and permeability kinetics, and that information can be used to model the input function. Importantly, the method is demonstrated in a murine xenograft study to yield K trans results consistent with literature values and suitable for compound studies.
Subject(s)
Contrast Media/chemistry , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Magnetic Resonance Imaging , Membrane Proteins/antagonists & inhibitors , Xenograft Model Antitumor Assays , Adaptor Proteins, Signal Transducing , Animals , Area Under Curve , Calcium-Binding Proteins , Cell Line, Tumor , Computer Simulation , Female , Immunoglobulin G/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Membrane Proteins/metabolism , Mice, Nude , Signal Processing, Computer-AssistedABSTRACT
We designed and fabricated a centrosymmetric material where one may be able to consider an efficient quadratic nonlinear interaction. We followed a solid phase-supported organic synthesis methodology to covalently bind a large number of highly nonlinear molecules to the surface of polystyrene nanospheres. Such chemically modified optically nonlinear latex spheres, when suspended in water, are seen to perfectly self-organize into a centrosymmetric lattice. Taking advantage of the nonlinear interaction located at the sphere-water interface and the photonic crystal properties of the fabricated material we were able to generate second-harmonic light visible to the naked eye.
ABSTRACT
La Dirección de atención primaria de salud (DAP) Tarragona-Valls, del Instituto Catalán de la Salud, decidió apostar por la filosofía de la globalización que desarrolla el método del Modelo Europeo de Excelencia Empresarial. Hace cinco años, la Dirección impulsó la utilización del método de la mejora continua de la calidad como instrumento para potenciar la cultura de la calidad en los centros sanitarios. Posteriormente se decidió dar un mayor impulso directivo en la gestión de la calidad total, incorporando el modelo EFQM.La aplicación de este modelo nos ha permitido iniciar conjuntamente la DAP Tarragona-Valls y la DAP Terres de l'Ebre, las líneas de trabajo actuales: potenciar la cultura de los valores en la organización a partir del ejemplo de las propias actitudes de los miembros del equipo directivo, para iniciar posteriormente la implantación del modelo EFQM en todos los centros de salud como instrumento de autoevaluación (AU)
