Cuantificación absoluta de la captación miocárdica de 99mTc-DPD en pacientes con amiloidosis cardiaca por depósitos de transtiretina (ATTR) / Absolute quantification of myocardial uptake of 99mTc-DPD in patients with cardiac amyloidosis due to transthyretin deposits (ATTR)

Objetivo Determinar la contribución diagnóstica de la cuantificación absoluta del depósito miocárdico de 99mTc-DPD en pacientes con amiloidosis cardiaca por depósitos de transtiretina (ATTR). Materiales y métodos Se realizó SPECT/TC a 41 pacientes con resultado gammagráfico positivo para amiloidosis cardiaca ATTR. Se dividió a los pacientes en dos grupos (grados2 y3 de Perugini) y se calcularon los SUVmax a nivel del hueso y de ambos ventrículos y el porcentaje de dosis calculado en estas áreas. Se empleó la prueba t de Student para comparar resultados y se calculó el área bajo la curva (AUC) para evaluar la eficacia diferencial y establecer unos puntos de corte discriminatorios entre ambos grupos de pacientes. Resultados Se observaron diferencias estadísticamente significativas en todas las variables a estudio, a excepción del SUVmax hueso. Las diferencias con mayor potencia estadística se observaron en las variables SUVmaxVD y el porcentaje de dosis en ambos ventrículos (p<0,001). El punto de corte obtenido para la variable SUVmaxVI fue de 8,620 (sensibilidad del 87,9% y especificidad del 100%; AUC: 0,966), mientras que el de la variable SUVmaxVD fue de 6,195 (sensibilidad del 81,8% y especificidad del 100%; AUC: 0,955). Conclusiones La cuantificación absoluta de la captación miocárdica de 99mTc-DPD en las imágenes SPECT/TC de pacientes con sospecha de amiloidosis cardiaca por depósitos de transtiretina supone una nueva herramienta diagnóstica que permite una adecuada clasificación de los pacientes, acorde a la escala de gradación visual de Perugini (AU)

Purpose To determine the diagnostic contribution of the absolute quantification of the myocardial deposit of 99mTc-DPD in patients with cardiac amyloidosis due to transthyretin deposits (ATTR). Materials and methods SPECT/CT was performed on 41 patients with positive scintigraphic results for ATTR cardiac amyloidosis. The patients were divided into two groups (Perugini grades2 and3) and the SUVmax at the level of the bone and both ventricles and the percentage of dose calculated in these areas were calculated. Student's t-test was used to compare results and the area under the curve (AUC) was calculated to assess differential efficacy and establish discriminatory cut-off points between both groups of patients. Results Statistically significant differences were observed in all the study variables, with the exception of SUVmax bone. The differences with the greatest statistical power were observed in the variables SUVmaxRV and the percentage of dose in both ventricles (P<.001). The cut-off point obtained for the variable SUVmaxLV was 8.620 (sensitivity 87.9% and specificity 100%; AUC: 0.966), while that of the variable SUVmaxRV was 6.195 (sensitivity 81.8% and specificity 100%; AUC: 0.955). Conclusions The absolute quantification of myocardial uptake of 99mTc-DPD in the SPECT/CT images of patients with suspected cardiac amyloidosis due to transthyretin deposits represents a new diagnostic tool that allows an adequate classification of patients, according to the visual grading scale of Perugini (AU)

Confirmación del origen de la fuga pleuroperitoneal mediante SPECT-TC en paciente en diálisis peritoneal / Confirmation of the pleuroperitoneal leak origin with a SPECT-CT in a patient on peritoneal dialysis

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METHODOLOGY AT CIEMAT WHOLE BODY COUNTER FOR IN VIVO MONITORING OF RADIOIODINE IN THE THYROID OF EXPOSED POPULATION IN CASE OF NUCLEAR EMERGENCY.

Iodine-131 is one of the main concerns from the point of view of radiological protection in a short term after a nuclear accident. The WBC Laboratory of CIEMAT has developed a methodology for in vivo monitoring of radioiodine in the thyroid of exposed individuals in case of emergency. Thyroid-neck phantoms of different sizes are required for calibrating the detection systems in appropriate counting geometries for the measurement of exposed population. A Low-Energy Germanium (LEGe) detector and a Fastscan Counter were calibrated using a set of thyroid phantoms fabricated by CIEMAT. Each neck phantom consists of a Lucite cylinder with a vial source of 131I. Counting efficiencies depending on age and thyroid sizes were obtained to be used to determine the activity of 131I in internally contaminated people. DL of 131I varies with the age, being in the range of 5-8 Bq for the LEGe detector and 26-42 Bq for the Fastscan. Detection of intakes resulting in Committed Effective doses far below 1 mSv are guaranteed for thyroid monitoring in a few days after the accidental exposure assuming a scenario of acute inhalation or ingestion of 131I by members of the public.

EFFICIENCY STUDY OF A LEGe DETECTOR SYSTEM FOR THE ASSESSMENT OF 241Am IN SKULL AT CIEMAT WHOLE BODY COUNTER.

(241)Am incorporation due to an incident or chronic exposure causes an internal dose, which can be evaluated from the total activity of this isotope in the skeleton several months after the intake. For this purpose, it is necessary to perform in vivo measurements of this bone-seeker radionuclide in appropriate counting bone geometries with very low attenuation of surrounded tissue and to extrapolate to total activity in the skeleton (ICRP 89, Basic anatomical and physiological data for use in radiological protection: reference values. 2001. 265). The work here presented refers to direct measurements of americium in the Cohen skull phantom at the CIEMAT Whole Body Counter (WBC) using low-energy germanium (LEGe) detectors inside a shielding room. The main goal was to determinate the most adequate head counting geometry for the in vivo detection of americium in the bone. The calibration of the in vivo LEGe system was performed with four detectors with 2 cm of distance to Cohen phantom. Two geometries were measured, on junction of frontal to parietal bones and frontal bone. The efficiencies are very similar in both geometries, the preferred counting geometry is the most comfortable for the person, with the LEGe detectors in the highest part of the frontal bone, near the junction with the parietal bone, CIEMAT WBC participated in a skull intercomparison exercise organised by WG7 of EURADOS (European Radiation Dosimetry Group e.V.). Efficiencies using three different skull phantoms were obtained. Measurements were performed for different head counting positions, four of them in the plane of symmetry and others over the temporal bone. The detector was placed in parallel with the calibration phantom at a distance of 1 cm. The main gamma emission of (241)Am, 59.5 keV (36 %), was used for comparing efficiency values. The lower efficiency was obtained over the frontal and occipital bones. Measurement with one LEGe detector over the parietal bone is the most efficient. The activity of each skull phantom was calculated using CIEMAT head calibration. Results of the EURADOS intercomparison are presented here for discussion.

Improvement of the electrochemical detection of catechol by the use of a carbon nanotube based biosensor.

Tyrosinase (Tyr) has been used frequently for the detection of phenolic compounds. The development of a biosensor based on this enzyme-integrated carbon nanotube (CNT) epoxy composite electrode (CNTECE) is described in order to perform measurements of catechol. The enzyme is immobilized into a matrix prepared by dispersion of multi-wall CNT (MWCNT) inside the epoxy resin forming a CNT epoxy-biocomposite (CNTEC-Tyr). The use of CNT improves the electronic transference between the enzyme and the electrode surface. The modified electrode was characterized electrochemically by amperometric and voltammetric techniques. An applied potential of -200 mV vs. Ag/AgC1 applied to the biocomposite based electrode was found to be optimal for electrochemical reduction of the enzymatic reaction products (quinones). The biosensor modified with MWCNT is also compared with a tyrosinase biosensor based on a graphite epoxy-composite (GECE-Tyr) showing a sensitivity of 294 microA/mM cm(2), a detection limit of 0.01 mM for a signal-to-noise ratio of 3 in a concentration range of 0.0-0.15 mM catechol with a response time of 20 s and an RSD of 8% (n = 3). The electrodes were stable for more than 24 h. A 90% increase of the signal indicated that the response is better with the biocomposite based on carbon nanotubes rather than with the graphite.

Modelo computadorizado 3-D para el estudio de la biomecánica del oído medio con el método de los elementos finitos (MEF) / Computerized 3-D model to study the biomechanics of the middle ear using the finite elements method

Basándonos en los datos ya conocidos sobre el comportamiento de los mecanismos de transmisión del sonido, creamos un modelo que reproduce la actividad mecánica del oído medio, utilizando el método de los elementos finitos. Diseñamos un modelo computadorizado que simula el comportamiento biomecánico de la membrana timpánica y la cadena osicular. Centramos el interés de la investigación en sus posibles aplicaciones clínicas, pudiendo introducir en el modelo las variables necesarias para la simulación de distintas situaciones: perforaciones timpánicas, fijaciones osiculares, interrupciones de la cadena, etc. Suministrando al programa simulador las características de la lesión creamos un modelo virtual sobre el que podemos valorar la hipoacusia existente y las posibilidades terapéuticas. Realizamos este modelo 3-D de membrana timpánica, martillo, yunque y estribo considerando su forma, peso, densidad, módulo de Young (N/m2) y coeficiente de Poisson, para las diferentes partes del sistema. Mostramos también la modelización de los elementos de unión entre los diferentes elementos tímpano-osiculares, incluidos músculos y ligamentos (AU)

Based on known data about the behavior of the sound transmission mechanism, we generate a model that reproduces the real mechanics of the middle ear by the finite elements method in the most exact manner possible. We designed a computerized model to simulate the biomechanic behavior of the ear drum/ossicular chain. The investigation focused on a possible clinical application, given that the variables necessary for simulation of several conditions can be introduced in our model: tympanic perforation, fixation of the ossicular chain, chain interruption, etc. Introducing the characteristics of the lesion virtually in a simulator program market is possible to reach conclusions about the conductive hypoacusis created and about therapeutic possibilities. The 3-D modelling of the tympanic membrane, malleus, incus and stapes is presented, considering form, weight, density, Young's module (N/m2) and Poisson coefficient for the different parts of each ossicle. The modeling of the union of the different tympanic-ossicular elements, including muscles and ligaments, is also shown (AU)

[Computerized 3-D model to study biomechanics of the middle ear using the finite element method]. / Modelo computadorizado 3-D para el estudio de la biomecánica del oído medio con el método de los elementos finitos (MEF).

Based on known data about the behavior of the sound transmission mechanism, we generate a model that reproduces the real mechanics of the middle ear by the finite elements method in the most exact manner possible. We designed a computerized model to simulate the biomechanic behavior of the ear drum/ossicular chain. The investigation focused on a possible clinical application, given that the variables necessary for simulation of several conditions can be introduced in our model: tympanic perforation, fixation of the ossicular chain, chain interruption, etc. Introducing the characteristics of the lesion virtually in a simulator program market is possible to reach conclusions about the conductive hypoacusis created and about therapeutic possibilities. The 3-D modelling of the tympanic membrane, malleus, incus and stapes is presented, considering form, weight, density, Young's module (N/m2) and Poisson coefficient for the different parts of each ossicle. The modeling of the union of the different tympanic-ossicular elements, including muscles and ligaments, is also shown.

[Febrile convulsions and meningitis]. / Convulsiones febriles y meningitis.

A hundred clinical records of children between the ages of 6 and 18 months were examined. These previously healthy children, were hospitalized after having their first febrile seizure. Lumbar puncture were performed on 42 of them, showing the existence of meningitis in 4 cases, 2 of which were bacterial meningitis. Previously, clinical criteria for meningitis diagnosis were: alteration of general condition, irritability, vomiting, bulging fontanelle and meningeal signs; in these 4 cases, the clinical criteria were noticed. In 17 puncture patients who did not fulfil clinical criteria, the cerebrospinal fluid was normal. The sensitivity and negative predictive value of these clinical criteria were 100% and their application in this series would have avoided the lumbar puncture in 40% of cases. The utility of peripheral white blood cell counts following TOOD's patterns for the bacterial meningitis diagnosis was low, with a sensibility of 50%. We conclude that the lumbar puncture in these children should not be performed as a routine measure.