Performance comparison of large-area SiPM arrays suitable for gamma ray detectors

[EN] The use of photosensors of the type Silicon Photomultpliers (SiPM) has widely been extended in recent years for multiple applications in both research and industry. However, there is a lack of comparative studies of different SiPMs under the same conditions, making it difficult to choose the most appropriate one for a specific application. SiPM arrays are suitable for gamma rays detectors, especially when covering large active areas. They are used either in clinical or pre-clinical scenarios, constituting Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) scanners, or just gamma cameras. The current work presents, for the first time, a comparative study between SensL, Hamamatsu Photonics and KETEK arrays of 12 x 12 SiPMs, with individual active areas of 3 mm x 3 mm, thus covering a total active area of about 5 cm x 5 cm. In this study, we have first evaluated their bias and temperature dependencies, resulting in a very similar behaviour with just a slightly larger dependency of the tested Hamamatsu parts. We also report the performance of detector blocks based on these three SiPM arrays, when coupled to pixelated crystal arrays and monolithic scintillators, in terms of photon impact estimation accuracy, as well as energy resolution. In the case of the monolithic crystals, also the depth of interaction resolution was determined. Both monolithic and pixelated blocks are nowadays widely used in academia or are commercially available for molecular imaging systems. The results obtained for the three SiPM arrays when using those crystals, are comparable, without observing any significant different among them.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No 695536). It has also been supported by the Spanish Ministerio de Economia, Industria y Competitividad under Grant TEC2016-79884-C2-1-R.Gonzalez-Montoro, A.; González Martínez, AJ. (2019). Performance comparison of large-area SiPM arrays suitable for gamma ray detectors. Biomedical Physics & Engineering Express. 5(4):1-10. https://doi.org/10.1088/2057-1976/ab0f6eS11054Henseler, D., Grazioso, R., Nan Zhang, & Schmand, M. (2009). SiPM performance in PET applications: An experimental and theoretical analysis. 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC). doi:10.1109/nssmic.2009.5402157Buzhan, P., Dolgoshein, B., Filatov, L., Ilyin, A., Kantzerov, V., Kaplin, V., … Smirnov, S. (2003). Silicon photomultiplier and its possible applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 504(1-3), 48-52. doi:10.1016/s0168-9002(03)00749-6Dolgoshein, B., Balagura, V., Buzhan, P., Danilov, M., Filatov, L., Garutti, E., … Tikhomirov, I. (2006). Status report on silicon photomultiplier development and its applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 563(2), 368-376. doi:10.1016/j.nima.2006.02.193Berard, P., Couture, M., Deschamps, P., Laforce, F., & Dautet, H. (2011). Performance measurement for a new low dark count UV-SiPM. 2011 IEEE Nuclear Science Symposium Conference Record. doi:10.1109/nssmic.2011.6154109Moliner, L., González, A. J., Soriano, A., Sánchez, F., Correcher, C., Orero, A., … Benlloch, J. M. (2012). Design and evaluation of the MAMMI dedicated breast PET. Medical Physics, 39(9), 5393-5404. doi:10.1118/1.4742850Gonzalez, A. J., Aguilar, A., Conde, P., Hernandez, L., Moliner, L., Vidal, L. F., … Benlloch, J. M. (2016). A PET Design Based on SiPM and Monolithic LYSO Crystals: Performance Evaluation. IEEE Transactions on Nuclear Science, 63(5), 2471-2477. doi:10.1109/tns.2016.2522179Gonzalez-Montoro, A., Benlloch, J. M., Gonzalez, A. J., Aguilar, A., Canizares, G., Conde, P., … Sanchez, F. (2017). Performance Study of a Large Monolithic LYSO PET Detector With Accurate Photon DOI Using Retroreflector Layers. IEEE Transactions on Radiation and Plasma Medical Sciences, 1(3), 229-237. doi:10.1109/trpms.2017.2692819González-Montoro, A., Sánchez, F., Martí, R., Hernández, L., Aguilar, A., Barberá, J., … González, A. J. (2018). Detector block performance based on a monolithic LYSO crystal using a novel signal multiplexing method. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 372-377. doi:10.1016/j.nima.2017.10.098Ronzhin, A., Albrow, M., Los, S., Martens, M., Murat, P., Ramberg, E., … Ritt, S. (2013). A SiPM-based TOF-PET detector with high speed digital DRS4 readout. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 703, 109-113. doi:10.1016/j.nima.2012.11.043Kim, C., McDaniel, D., Malaney, J., McBroom, G., Peterson, W., Tran, V. H., … Ganin, A. (2012). Time-of-flight PET-MR detector development with silicon photomultiplier. 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC). doi:10.1109/nssmic.2012.6551808Schaart, D. R., van Dam, H. T., Seifert, S., Vinke, R., Dendooven, P., Löhner, H., & Beekman, F. J. (2009). A novel, SiPM-array-based, monolithic scintillator detector for PET. Physics in Medicine and Biology, 54(11), 3501-3512. doi:10.1088/0031-9155/54/11/01

Design and implementation of PET detectors based on monolithic crystals and SiPMs

Esta tesis doctoral se centra tanto en el diseño como en la validación experimental de detectores de rayos gamma para escáneres de tomografía por emisión de positrones (PET, del inglés Positron Emission Tomography). El objetivo principal de esta tesis es el diseño de innovadores bloques detectores PET de alto rendimiento. La técnica PET constituye una de las principales herramientas diagnósticas en medicina nuclear, que es una especialidad médica que utiliza sustancias radiactivas con fines diagnósticos y terapéuticos. Esta técnica de imagen médica permite visualizar procesos fisiológicos y bioquímicos del cuerpo humano in vivo, mediante la administración del elemento radiotrazador. Los radiotrazadores son compuestos químicos, similares a las sustancias naturales del cuerpo, en las que uno o más átomos son sustituidos por radionúclidos emisores de fotones, para su uso en gamma cámaras y SPECT, o de positrones (la antipartícula del electrón) para PET. En el primer capítulo de la tesis se introducen las principales técnicas de imagen médicas utilizadas en la actualidad, incluyendo las técnicas de imagen funcional, de imagen anatómica y su fusión para dar lugar a imágenes multimodales. En el segundo capítulo, dado que la técnica PET es el foco de estudio central de la tesis, se describe en detalle su historia mostrando los avances de los últimos 60 años, hasta establecerse en la actualidad como una herramienta diagnóstica imprescindible en medicina. En este capítulo se describen también los principios físicos de la técnica, los algoritmos de reconstrucción y las correcciones de imagen que se emplean. Así mismo el capítulo describe el papel fundamental del tiempo de vuelo de los fotones producidos en la aniquilación del positrón y el electrón, y de la coordenada de profundidad de interacción (DOI, del inglés Depth of Interaction). A continuación, en el tercer capítulo, se describen con detalle los materiales y métodos empleados en PET, haciendo especial énfasis en aquellos utilizados para el desarrollo de esta tesis. En la actualidad, la mayoría de sistemas PET comerciales están constituidos por bloques detectores basados en cristales centelleadores pixelados (matrices de pequeños cristales). Dichos cristales permiten estimar las coordenadas (x, y) del impacto del fotón de manera sencilla, sin embargo, la obtención de la coordenada de profundidad de interacción (z), imprescindible para obtener una buena resolución espacial sobretodo en los bordes del campo de visión del escáner, resulta una tarea difícil que requiere el uso de materiales adicionales y por tanto incrementan el precio del escáner. Una alternativa a la configuración anterior, es el uso de cristales monolíticos o continuos los cuales están constituidos por una única pieza de material centelleador que permite “observar” la distribución de fotones ópticos generada. Esta información es utilizada para obtener con precisión las coordenadas 3D de impacto del fotón (x, y, z) en el cristal sin necesidad de otros materiales. Por este motivo, en esta tesis doctoral se ha llevado a cabo el diseño de detectores basados en estos cristales monolíticos acoplados a fotosensores de estado sólido compatibles con equipos de resonancia magnética. En este capítulo se muestran los resultados obtenidos en la caracterización de diferentes tipos de cristales, geometrías y tratamientos aplicados a la superficie de los bloques detectores. Finalmente se presenta una breve descripción de los equipos que han motivado los estudios realizados en la tesis. Dado que el formato de esta tesis esta basado en un compendio de los artículos más relevantes publicados durante el transcurso de los estudios de doctorado, el cuarto capítulo incluye una copia de los artículos publicados más relevantes tal y como se muestran en las revistas científicas. Se presentan un total de 6 artículos que recogen los principales resultados obtenidos durante los estudios de doctorado. Dada la calidad de los resultados globales obtenidos, dos de los bloques detectores diseñados constituyen la base de dos sistemas PET dedicados al estudio del cerebro humano, el inserto MINDView (proyecto europeo FP7) y el escáner CareMiBrain (proyecto europeo Horizont 2020). El equipo MINDView, que es un inserto compatible con todas las resonancias magnéticas del mundo, ha sido instalado en el hospital de la Universidad Técnica de Múnich y actualmente está en la fase previa a comenzar un estudio con pacientes. En la tesis se recogen las pruebas de validación realizadas tanto a nivel del bloque detector como del equipo final. Respecto al equipo CareMiBrain, que es un escáner PET dedicado al estudio del Alzheimer y de otras enfermedades de deterioro cognitivo, ha sido instalado en Madrid y los primeros pacientes ya han sido escaneados satisfactoriamente. En la tesis se recoge el diseño y los resultados de caracterización del bloque detector. Además del diseño y caracterización de dichos bloques detectores, se muestran también los resultados y conclusiones obtenidas en otros estudios de investigación, tales como la caracterización de una gran variedad de geometrías de detectores, la optimización de la extracción de la luz en cristales BGO (fueron pioneros en los equipos PET pero se sustituyeron por los nuevos cristales que son más rápidos), tanto en forma pixelada como en bloques monolíticos, y un enfoque de detector híbrido que utiliza capas monolíticas y pixeladas en un mismo bloque detector. Se ha prestado especial atención a la caracterización y determinación de la DOI dentro de los bloques monolíticos, reduciendo el error de paralaje en la imagen final reconstruida. El quinto capítulo contiene un resumen y conclusiones de los resultados de esta tesis. El sexto y séptimo capítulo, contienen un resumen en castellano y valenciano respectivamente, de los objetivos, motivación, materiales, métodos, resultados y conclusiones de la tesis doctoral. Finalmente, el Apéndice A muestra una lista completa de los artículos científicos publicados durante la tesis (incluyendo los seleccionados para el compendio).This doctoral thesis focuses on both the design and experimental validation of gamma-ray detectors suitable for Positron Emission Tomography (PET) scanners. The main objective is the design of high efficiency PET detector blocks. The PET technique constitutes one of the main diagnostic tools in Nuclear Medicine, which is a medical specialty that uses radioactive substances for diagnostic and therapeutic purposes. This Medical Imaging technique allows one to visualize physiological and biochemical processes of the human body in vivo, by means of the administration of a radiotracer element. Radiotracers are chemical compounds, similar to the body's natural substances, in which one or more atoms are replaced by radionuclides that emit photons, for use in gamma and SPECT cameras, or positrons (the antiparticle of the electron) for PET. The first chapter of the thesis introduces the main Medical Imaging techniques that are currently used, including functional and anatomical imaging as well as their possible merging generating multimodal images. In the second chapter, since PET imaging is the focus of this thesis, an extensive description of this technique is outlined. The chapter begins with a brief history of PET, showing the advances over the last 60 years until being established as an essential diagnostic tool in medicine. This chapter also describes the physical principles of PET, the reconstruction algorithms and the applied image corrections techniques. In addition to the basic concepts, the role of Time of Flight (TOF) and DOI in PET are described in this chapter. The third chapter describes in detail the materials and methods used in PET, making special emphasis on those used for the development of this work. Currently, most commercial PET systems consist of detector blocks based on pixelated scintillation crystals (matrices of small crystals). These crystals allow one for an easy estimation of the planar impact coordinates of the gamma-ray within the crystal (x, y). However, estimating the depth of interaction coordinate (z), which is essential to obtain a good spatial resolution especially at the edges of the field of view of the scanner, is a difficult task that requires the use of extra materials and therefore increases the price of the scanner. An alternative to that configuration is the use of monolithic crystals, which are constituted by a single piece of scintillating material that permits to characterize the complete, flashing light distribution. This information is used to obtain the 3D impact coordinates of the photon (x, y, z) within the crystal with high resolution and without the need for extra materials. For this reason, this doctoral thesis focusses on the design of PET detector blocks based on monolithic crystals coupled to solid state photosensors. These components are compatible with magnetic fields and therefore, suitable for their simultaneous use with Magnetic Resonance Imaging (MRI) systems. This chapter summarizes the results obtained in the characterization of different types of crystals, geometries and treatments applied to the crystal surface of the detector blocks. Finally, a brief description of the PET systems that have motivated the studies carried out in the thesis is presented. Since this thesis is based on a compendium of the most relevant articles published during the course of the PhD studies, Chapter 4 presents a copy of those research articles, as exactly shown in the different per-reviewed journals, including a brief introduction highlighting their main results. A total of 6 articles are presented, which contain the main results obtained during the doctoral studies. Given the quality of the overall obtained results, two of the designed detector blocks have been selected as the basis of two PET systems dedicated to the study of the human brain namely, i) the MINDView insert (European Union FP7 project) and, ii) the CareMiBrain stand-alone scanner (European Union project Horizon 2020). The MINDView system, which is a PET insert compatible with MRI scanners, has been installed at Technical University of Munich and is currently starting scanning patients with depression and schizophrenia. The thesis includes the validation tests carried out at the level of the detector block and of the final equipment. The CareMiBrain system, which is a PET scanner dedicated to the study of the Alzheimer disease and other causes of cognitive decline, has been installed in a hospital in Madrid and the first patients have already been successfully scanned. The thesis contains the design and results of characterization of the CareMiBrain detector block. In addition to the design and characterization of those detector blocks, other research studies have been carried out during the course of this thesis, such as the characterization of a large variety of photosensor geometries, the optimization of light extraction in BGO crystals, both in pixelated and monolithic geometries, and a hybrid detector approach that uses monolithic and pixellated layers in the same detector block. Special emphasis has been given to the characterization and estimation of the DOI coordinate within monolithic blocks, reducing the parallax error in the reconstructed final image. Chapter 5 contains a summary of the results and conclusions of this thesis. Chapters 6 and 7 summarize, in Spanish and Valencian, respectively, the objectives, motivation, materials, methods, results and conclusions of this doctoral thesis. A complete list of all the per-reviewed articles (including those selected for this compendium) and the conference proceedings published during the development of this thesis can be found in Appendix A

Socioeconomic Status, Health and Life-Style Settings as Psychosocial Risk Factors for Road Crashes in Young People: Assessing the Colombian Case

The social determinants of health influence both psychosocial risks and protective factors, especially in high-demanding contexts, such as the mobility of drivers and non-drivers. Recent evidence suggests that exploring socioeconomic status (SES), health and lifestyle-related factors might contribute to a better understanding of road traffic crashes (RTCs). Thus, the aim of this study was to construct indices for the assessment of crash rates and mobility patterns among young Colombians who live in the central region of the country. The specific objectives were developing SES, health and lifestyle indices, and assessing the self-reported RTCs and mobility features depending on these indices. A sample of 561 subjects participated in this cross-sectional study. Through a reduction approach of Principal Component Analysis (PCA), three indices were constructed. Mean and frequency differences were contrasted for the self-reported mobility, crash rates, age, and gender. As a result, SES, health and lifestyle indices explained between 56.3-67.9% of the total variance. Drivers and pedestrians who suffered crashes had higher SES. A healthier lifestyle is associated with cycling, but also with suffering more bike crashes; drivers and those reporting traffic crashes have shown greater psychosocial and lifestyle-related risk factors. Regarding gender differences, men are more likely to engage in road activities, as well as to suffer more RTCs. On the other hand, women present lower healthy lifestyle-related indices and a less active implication in mobility. Protective factors such as a high SES and a healthier lifestyle are associated with RTCs suffered by young Colombian road users. Given the differences found in this regard, a gender perspective for understanding RTCs and mobility is highly suggestible, considering that socio-economic gaps seem to differentially affect mobility and crash-related patterns

Calibration of Gamma Ray Impacts in Monolithic-Based Detectors Using Voronoi Diagrams

[EN] Molecular imaging systems, such as positron emission tomography (PET), use detectors providing energy and a 3-D interaction position of a gamma ray within a scintillation block. Monolithic crystals are becoming an alternative to crystal arrays in PET. However, calibration processes are required to correct for nonuniformities, mainly produced by the truncation of the scintillation light distribution at the edges. We propose a calibration method based on the Voronoi diagrams. We have used $50 \times 50 \times 15$ mm(3) LYSO blocks coupled to a $12\times 12$ SiPMs array. We have first studied two different interpolation algorithms: 1) weighted average method (WAM) and 2) natural neighbor (NN). We have compared them with an existing calibration based on 1-D monomials. Here, the crystal was laterally black painted and a retroreflector (RR) layer added to the entrance face. The NN exhibited the best results in terms of XY impact position, depth of Interaction, and energy, allowing us to calibrate the whole scintillation volume. Later, the NN interpolation has been tested against different crystal surface treatments, allowing always to correct edge effects. Best energy resolutions were observed when using the reflective layers (12%-14%). However, better linearity was observed with the treatments using black paint. In particular, we obtained the best overall performance when lateral black paint is combined with the RR.This work was supported in part by the European Research Council through the European Union's Horizon 2020 Research and Innovation Program under Grant 695536, and in part by the Spanish Ministerio de Economia, Industria y Competitividad under Grant TEC2016-79884-C2-1-R.Freire, M.; Gonzalez-Montoro, A.; Sánchez Martínez, F.; Benlloch Baviera, JM.; González Martínez, AJ. (2020). Calibration of Gamma Ray Impacts in Monolithic-Based Detectors Using Voronoi Diagrams. IEEE Transactions on Radiation and Plasma Medical Sciences. 4(3):350-360. https://doi.org/10.1109/TRPMS.2019.2947716S3503604

Phosphorus removal and recycled from tertiary effluent in sewage treatment plant using graphene modified with magnetic nanoparticles (M@GO).

Phosphorus is employed in detergents, as fertilizers in agriculture, etc. As a nutrient for plants, too much phosphorus can cause increased growth of algae and large aquatic plants, which can result in decreased levels of dissolved oxygen– a process called eutrophication. On the other hand, P is a relatively limited resource, considered by the European Union as a strategic interest material. Thus, the removal and recycled of P from the sewage treatment plants is of great interest to the society. In this work, a new patented magnetic graphene oxide (M@GO) for the removal of phosphorus from wastewater is studied. The main technical advantage of this solid adsorbent is its easy separation from the treated water by applying a magnetic field. The key factors affecting the sorption and elution efficiency are studied. The thermodynamic adsorption model that provides a best fit was the Langmuir isotherm. The mass transfer kinetic model indicates that the mass transfer of P between the bulk liquid and the solid surface is not the rate-limiting step of the adsorption process. The P adsorption on M@GO was demonstrated by TEM, XPS, FTIR. After the adsorption, an ammonia aqueous solution has provided to be the best eluent to recover the phosphorus from the solid adsorbent, as ammonium phosphate, with recovery yields above 90%. The results of this work have driven to the design of a new magnetic reactor for the treatment of waste water. Acknowledgements The authors thank to Spanish Ministerio de Ciencia e Innovación, Project PID2021-126794OB and the II Plan Propio UMA.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Tratamento com brometo de piridostigmina em canino com dificuldade de esvaziar a bexiga em canino positivo para miastenia gravis adquirida

Introduction: Acquired myasthenia gravis (AGM) is an immune-mediated disease that presents a decrease in the number or functionality of acetylcholine receptors at the nicotinic level. This leads to less effective muscle contraction. The most common clinical manifestation is episodic weakness that increases with exercise and improves with rest. Other clinical signs are: regurgitation and voice changes. The purpose of this report is to describe a canine, female with dysuria without stranguria who was taken to the Hospital School of Veterinary Medicine of the University of Buenos Aires. Methods: blood and urine tests, urine cultures, spinal radiographs, abdominal ultrasound, electromyography (EMG) of the anal sphincter and repetitive stimulation were performed. Antibodies against acetylcholine receptors (ACRA) were measured. Results: blood tests, urinalysis, spinal radiographs and abdominal ultrasound were normal. Urine cultures were negative. Anal sphincter EMG was preserved. Repetitive stimulation EMG was compatible with MGA. The patient was ACRA positive and his response to treatment with pyridostigmine bromide (BRP) was favorable. Conclusions: include MGA in canine patients with dysuria in the deferential diagnosis.Introducción: La miastenia gravis adquirida (MGA) es una enfermedad inmunomediada, que presenta disminución en el número o funcionalidad de receptores de la acetilcolina a nivel nicotínico. Esto conlleva que la contracción muscular sea menos efectiva. La manifestación clínica más común es la debilidad episódica que aumenta con el ejercicio y mejora con el reposo. Otros signos clínicos son regurgitaciones y cambios de voz. El propósito de este reporte es describir un canino hembra con disuria sin estranguria que fue llevado a consulta al Hospital Escuela de Medicina Veterinaria de la Universidad de Buenos Aires. Metodología: se realizaron análisis de sangre y orina, urocultivos, radiografías de columna, ecografía abdominal, electromiografía (EMG) de esfínter anal y de estimulación repetitiva, se midieron anticuerpos contra receptores de la acetilcolina (ACRA). Resultados: fueron normales los análisis de sangre, urianálisis, radiografías de columna y ecografía de abdomen. Los urocultivos fueron negativos. La EMG del esfínter anal fue conservada. La EMG estimulación repetitiva fue compatible con MGA. El paciente resultó ACRA positivo y su respuesta al tratamiento con bromuro de piridostigmina (BRP) fue favorable. Conclusiones: incluir dentro del diagnóstico deferencial a la MGA en pacientes caninos con disuria.Introdução: a miastenia grave adquirida (MGA) é uma doença imunomediada, que apresenta diminuição no número ou funcionalidade dos receptores da acetilcolina a nível nicotínico. Isto, produz uma contração muscular menos efetiva. A manifestação clínica mais comum é a debilidade motora que aumenta o exercício e melhora com o repouso. Outros estados clínicos são: regurgitação e mudança na voz. O propósito deste artigo é descrever um canino fêmea com disúria sem estrangúria que foi levado a consulta no Hospital da Escola de Medicina Veterinária da Universidade de Buenos Aires. Metodologia: realizaram análises de sangue e urina, urocultura, radiografia da coluna, ecografia abdominal, eletromiografia (EMG) e esfíncter anal e de estimulação repetitiva, mediram anticorpos contra receptores de acetilcolina (ACRA). Resultados: análises de sangue, urinálise, radiografias de coluna e ecografia de abdômen foram normais. As uroculturas foram negativas, A EMG de esfíncter anal foi conservada. A EMG estimulação repetitiva foram compatíveis com MGA. O paciente resultou ACRA positivo e sua resposta ao tratamento com bromuro de piridostigma (BRP) foi favorável. Conclusão: incluir dentro do diagnóstico diferencial a MGA em pacientes com disúria

Pediatric minor head trauma: do cranial CT scans change the therapeutic approach?

OBJECTIVES: 1) To verify clinical signs correlated with appropriate cranial computed tomography scan indications and changes in the therapeutic approach in pediatric minor head trauma scenarios. 2) To estimate the radiation exposure of computed tomography scans with low dose protocols in the context of trauma and the additional associated risk. METHODS: Investigators reviewed the medical records of all children with minor head trauma, which was defined as a Glasgow coma scale ≥13 at the time of admission to the emergency room, who underwent computed tomography scans during the years of 2013 and 2014. A change in the therapeutic approach was defined as a neurosurgical intervention performed within 30 days, hospitalization, >;12 hours of observation, or neuro-specialist evaluation. RESULTS: Of the 1006 children evaluated, 101 showed some abnormality on head computed tomography scans, including 49 who were hospitalized, 16 who remained under observation and 36 who were dismissed. No patient underwent neurosurgery. No statistically significant relationship was observed between patient age, time between trauma and admission, or signs/symptoms related to trauma and abnormal imaging results. A statistically significant relationship between abnormal image results and a fall higher than 1.0 meter was observed (p=0.044). The mean effective dose was 2.0 mSv (0.1 to 6.8 mSv), corresponding to an estimated additional cancer risk of 0.05%. CONCLUSION: A computed tomography scan after minor head injury in pediatric patients did not show clinically relevant abnormalities that could lead to neurosurgical indications. Patients who fell more than 1.0 m were more likely to have changes in imaging tests, although these changes did not require neurosurgical intervention; therefore, the use of computed tomography scans may be questioned in this group. The results support the trend of more careful indications for cranial computed tomography scans for children with minor head trauma

Miastenia gravis adquirida generalizada en caninos y su presentación con miositis de músculos masticatorios

Cinco caninos de 4 a 9 años de edad fueron diagnosticados con miastenia gravis adquirida en asociación con miositis de músculos masticatorios, en el Hospital Escuela de la Facultad de Ciencias Veterinarias de Buenos Aires, durante el periodo 2013-2016. El diagnóstico se confirmó mediante la realización de pruebas serológicas específicas, electromiografías y biopsias musculares de los músculos masticatorios. Se realizó el tratamiento con bromuro de piridostigmina y prednisolona, por el origen inmunomediado de ambas enfermedade

Pan-cancer molecular patterns and biological implications associated with a tumor-specific molecular signature

Studying tissue-independent components of cancer and defining pan-cancer subtypes could be addressed using tissue-specific molecular signatures if classification errors are controlled. Since PAM50 is a well-known, United States Food and Drug Administration (FDA)-approved and commercially available breast cancer signature, we applied it with uncertainty assessment to classify tumor samples from over 33 cancer types, discarded unassigned samples, and studied the emerging tumor-agnostic molecular patterns. The percentage of unassigned samples ranged between 55.5% and 86.9% in non-breast tissues, and gene set analysis suggested that the remaining samples could be grouped into two classes (named C1 and C2) regardless of the tissue. The C2 class was more dedifferentiated, more proliferative, with higher centrosome amplification, and potentially more TP53 and RB1 mutations. We identified 28 gene sets and 95 genes mainly associated with cell-cycle progression, cell-cycle checkpoints, and DNA damage that were consistently exacerbated in the C2 class. In some cancer types, the C1/C2 classification was associated with survival and drug sensitivity, and modulated the prognostic meaning of the immune infiltrate. Our results suggest that PAM50 could be repurposed for a pan-cancer context when paired with uncertainty assessment, resulting in two classes with molecular, biological, and clinical implications.Fil: Rocha, Darío Gastón. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: García, Iris Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas. Universidad Católica de Córdoba. Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Bioquímica Clínica; ArgentinaFil: González Montoro, Aldana María. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Llera, Andrea Sabina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación Instituto Leloir; ArgentinaFil: Prato, Laura Beatriz. Universidad Nacional de Villa María. Instituto Académico Pedagógico de Ciencias Básicas y Aplicadas; ArgentinaFil: Girotti, Maria Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Soria, Gastón. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez, Elmer Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas. Universidad Católica de Córdoba. Centro de Investigación y Desarrollo en Inmunología y Enfermedades Infecciosas; Argentin