k-Space tutorial: an MRI educational tool for a better understanding of k-space

A main difference between Magnetic Resonance (MR) imaging and other medical imaging modalities is the control over the data acquisition and how it can be managed to finally show the adequate reconstructed image. With some basic programming adjustments, the user can modify the spatial resolution, field of view (FOV), image contrast, acquisition velocity, artifacts and so many other parameters that will contribute to form the final image. The main character and agent of all this control is called k-space, which represents the matrix where the MR data will be stored previously to a Fourier transformation to obtain the desired image

HIVE Tracker: A tiny, low-cost, and scalable device for sub-millimetric 3D positioning

Positional tracking systems could hugely benefit a number of niches, including performance art, athletics, neuroscience, and medicine. Commercial solutions can precisely track a human inside a room with sub-millimetric precision. However, these systems can track only a few objects at a time; are too expensive to be easily accessible; and their controllers or trackers are too large and inaccurate for research or clinical use. We present a light and small wireless device that piggybacks on current commercial solutions to provide affordable, scalable, and highly accurate positional tracking. This device can be used to track small and precise human movements, to easily embed custom objects inside of a VR system, or to track freely moving subjects for research purposes

SAGIMA: An Easy-to-Use and Low Cost WEB-PACS System for an Optimal Access and Management of a Digital Angiography Database

Over several years, digital angiography studies from the Hemodynamic Unit of the Hospital Clínico Universitario (Valencia, Spain) have been stored in CD’s using first revisions of DICOM 3.0. In order to centralize the management and facilitate the access to these studies and reports, an easy to use and low cost WEB-PACS system that we have called SAGIMA has been developed in close collaboration between the BET Research Group of the Universitat Politècnica de València and the Cardiology Department of the Hospital Clínic

PETra: Software Tool for a Semiautomatic Positron Emission Tomography Image Analysis and its Application to the Study of Brain Glucose Consumption in Rats

[EN] This work presents a Positron Emission Tomography (PET) image analysis tool and its application to the study of rat brain glucose consumption (PETra comes from PET+rat). The described methodology has four steps: a preprocessing of PET images, a coregistration of these images with an atlas, a semiautomatic segmentation of the regions of interest in the rat brain and a 3D reconstruction of these regions to obtain the volumes of interest. Brain glucose uptake was quantified as Standardized Uptake Value (SUV). This tool was applied to nine Wistar rats, young (4-7 months) and old (22-24 months) groups, to study the effect of aging on brain glucose consumption and the difference between sexes. Results showed a lower glucose uptake in old rats than in young rats, regardless gender; while young female rats showed higher glucose consumption than young male rats, whereas these differences disappeared with aging. The developed tool allows the quantification of glucose in rat brain. Results show the accuracy of the tool to define ranges of variation in a population of young and old rats, showing a decrease in glucose consumption in aging.Del Canto, I.; Lopez-Grueso, R.; Gambini, J.; Monleón, D.; Borrás, C.; Viña, J.; Moratal, D. (2015). PETra: Software Tool for a Semiautomatic Positron Emission Tomography Image Analysis and its Application to the Study of Brain Glucose Consumption in Rats. IEEE Latin America Transactions. 13(3):876-884. doi:10.1109/TLA.2015.7069118S87688413

Segmentación de imágenes de resonancia magnética en contraste de fase para el estudio de la dinámica del líquido cefalorraquídeo perimedular

La imagen de resonancia magnética en contraste de fase permite estudiar la dinámica del líquido cefalorraquídeo (LCR) perimedular de manera cuantitativa. Sin embargo la anatomía propia del espacio subaracnoideo dificulta la segmentación del LCR debido a la presencia de estructuras vasculares y nervios raquídeos. El objetivo de este trabajo es describir un método de segmentación semiautomático para el estudio de la dinámica del LCR perimedular. El proceso se inicializa con un punto semilla dentro de la región a analizar. El algoritmo crea un mapa de correlación, calcula un valor de umbral y clasifica píxeles de LCR combinando diversas características temporales del comportamiento del flujo como atributos de entrada a un algoritmo k-medias. Un observador llevó a cabo 10 veces la segmentación en 5 sujetos sanos y se calculó el volumen por ciclo y el área en el espacio perimedular C2C3. Las variaciones de las medidas fueron evaluadas como una estimación de la reproducibilidad del método. Para esto se calculó el coeficiente de variación. La variabilidad de las medidas fue menor del 5%. El método facilita la cuantificación del LCR perimedular. En 16 sujetos sanos se cuantificó el volumen por ciclo de LCR y el área en el espacio C2C3 y cisterna prepontina

Design and Assembly Procedures for Large-Sized Biohybrid Scaffolds as Patches for Myocardial Infarct

[EN] Objective: To assemble a biohybrid cardiac patch consisting of a large (5x5 cm) elastomer scaffold whose pores are filled with a self-assembling peptide (SAP) gel entrapping adipose stem cells, to be used as a novel implant in a big animal model (sheep) of myocardial infarction. The study focuses on the way to determine optimal procedures for incorporating the SAP solution and the cells in the patch to ensure cell colonization and a homogeneous cell distribution in the construct before implantation. The problems associated with the scale-up of the different procedures raised by the large size of the construct are discussed. Materials and Methods: Experiments were performed to choose between different assembling alternatives: incorporation of the SAP gel before cell seeding or simultaneous SAP and cell loading of the scaffold; surface seeding of cells or cell injection into the scaffold pores; dissemination of the cells throughout the scaffold before incubation by gentle shaking or by centrifugation. Immunocytochemistry techniques and confocal and scanning electron microscopies were employed to assess and quantify cell colonization of the material and early cell distribution. Cell concentrations and the uniformity of cellular distribution throughout the scaffold were taken as the main criteria to decide between the different alternative procedures. Results: The combination of peptide preloading, cell injection, and shaking before incubation yielded the best results in terms of greater cell density and the most uniform distribution after 24 h of culture compared with the other methods. These techniques could be scaled-up to obtain large biohybrid cardiac patches with success. Conclusions: The results obtained after the different seeding methods allowed us to establish an effective protocol for the assembly of large biohybrid patches for their subsequent implantation in the heart of a big animal model of myocardial infarct in the context of a preclinical study.The authors acknowledge the financing from the European Commission through the ‘‘Regeneration of cardiac tissue assisted by bioactive implants’’ (RECATABI) FP7 NMP3-SL-2009-229239 project. MMP acknowledges support of Instituto de Salud Carlos III with assistance from the European Regional Development Fund through CIBER-BBN initiative.Martínez Ramos, C.; Rodríguez Pérez, E.; Perez Garnes, M.; Chachques, JC.; Moratal Pérez, D.; Vallés Lluch, A.; Monleón Pradas, M. (2014). Design and Assembly Procedures for Large-Sized Biohybrid Scaffolds as Patches for Myocardial Infarct. Tissue Engineering Part C Methods. 20(10):817-827. https://doi.org/10.1089/ten.TEC.2013.0489S817827201

Incidence, Outcomes, and Predictors of Ventricular Thrombus after Reperfused ST-Segment-Elevation Myocardial Infarction by Using Sequential Cardiac MR Imaging

[EN] Purpose: To characterize the incidence, outcomes, and predictors of left ventricular (LV) thrombus by using sequential cardiac magnetic resonance (MR) imaging after ST-segment-elevation myocardial infarction (STEMI). Materials and Methods: Written informed consent was obtained from all patients, and the study protocol was approved by the committee on human research. In a cohort of 772 patients with STEMI, 392 (mean age, 58 years; range, 24-89 years) were retrospectively selected who were studied with cardiac MR imaging at 1 week and 6 months. Cardiac MR imaging guided the initiation and withdrawal of anticoagulants. Patients with LV thrombus at 6 months were restudied at 1 year. For predicting the occurrence of LV thrombus, a multiple regression model was applied. Results: LV thrombus was detected in 27 of 392 patients (7%): 18 (5%) at 1 week and nine (2%) at 6 months. LV thrombus resolved in 22 of 25 patients (88%) restudied within the first year. During a mean follow-up of 181 weeks 6 168, patients with LV thrombus displayed a very low rate of stroke (0%), peripheral embolism (0%), and severe hemorrhage (n = 1, 3.7%). LV ejection fraction (LVEF) less than 50% (P < .001) and anterior infarction (P = .008) independently helped predict LV thrombus. The incidence of LV thrombus was as follows: (a) nonanterior infarction, LVEF 50% or greater (one of 135, 1%); (b) nonanterior infarction, LVEF less than 50% (one of 50, 2%); (c) anterior infarction, LVEF 50% or greater (two of 92, 2%); and (d) anterior infarction, LVEF less than 50% (23 of 115, 20%) (P < .001 for the trend). Conclusion: Cardiac MR imaging contributes information for the diagnosis and therapy of LV thrombus after STEMI. Patients with simultaneous anterior infarction and LVEF less than 50% are at highest risk. (C) RSNA, 2017Study supported by Instituto de Salud Carlos III and FEDER (CB16/11/00486, PI14/00271, PIE15/00013) and Generalitat Valenciana (PROMETEO/2013/007).Cambronero-Cortinas, E.; Bonanad, C.; Monmeneu, J.; López-Lereu, M.; Gavara-Doñate, J.; De Dios, E.; Rios, C.... (2017). Incidence, Outcomes, and Predictors of Ventricular Thrombus after Reperfused ST-Segment-Elevation Myocardial Infarction by Using Sequential Cardiac MR Imaging. Radiology. 284(2):372-380. https://doi.org/10.1148/radiol.2017161898S372380284

Schwann-cell cylinders grown inside hyaluronic-acid tubular scaffolds with gradient porosity

[EN] Cell transplantation therapies in the nervous system are frequently hampered by glial scarring and cell drain from the damaged site, among others. To improve this situation, new biomaterials may be of help. Here, novel single-channel tubular conduits based on hyaluronic acid (HA) with and without poly-l-lactide acid fibers in their lumen were fabricated. Rat Schwann cells were seeded within the conduits and cultured for 10days. The conduits possessed a three-layered porous structure that impeded the leakage of the cells seeded in their interior and made them impervious to cell invasion from the exterior, while allowing free transport of nutrients and other molecules needed for cell survival. The channel's surface acted as a template for the formation of a cylindrical sheath-like tapestry of Schwann cells continuously spanning the whole length of the lumen. Schwann-cell tubes having a diameter of around 0.5mm and variable lengths can thus be generated. This structure is not found in nature and represents a truly engineered tissue, the outcome of the specific cell-material interactions. The conduits might be useful to sustain and protect cells for transplantation, and the biohybrids here described, together with neuronal precursors, might be of help in building bridges across significant distances in the central and peripheral nervous system.The authors acknowledge financing through projects MAT2011-28791-C03-02 and 03, and ERA-NET NEURON project PRI-PIMNEU-2011-1372. We thank the Cytomics Core Facility at Principe Felipe Research Center (CIPF, Valencia, Spain) for their support and advice in flow cytometry experiments, and the Electron Microscopy Service at the UPV, where the SEM images were obtained. The authors thankfully acknowledge the reviewers' comments, which have helped to improve the clarity of the paper's presentation.Vilariño Feltrer, G.; Martínez Ramos, C.; Monleon De La Fuente, A.; Vallés Lluch, A.; Moratal Pérez, D.; Barcia Albacar, JA.; Monleón Pradas, M. (2016). Schwann-cell cylinders grown inside hyaluronic-acid tubular scaffolds with gradient porosity. Acta Biomaterialia. 30:199-211. https://doi.org/10.1016/j.actbio.2015.10.040S1992113