Utilidad clínica del Antígeno Carcinoembrionario (ACE), Tomografía convencional (TC) y PET-CT en el diagnóstico de adenocarcinoma colorrectal recidivante / Clinical utility of Carcinoembryonic Antigen (ACE), conventional tomography (CT) and PET-CT in the diagnosis of recurrent colorectal adenocarcinoma

Introduction: Colorectal cancer is one of the most prevalent tumors in the world. In the surveillance setting of recurrent colorectal cancer, laboratory test like carncinoembryonic antigen (CEA) and imaging tests like computed tomography (CT) and positron emission tomography (PET/CT) are available. We performed this study to establish the predictive accuracy of these tests to an early identification of recurrent colorectal cáncer. Materials and Methods: Thirty six patients at stages I , III and IV, after single metastasis resection of colorectal cáncer were identified. We assessed the utility of CEA, CT and PET-CT in the follow-up of these patients to improve the diagnosis of recurrent disease. Results: Of 36 studied patients, 27 /75%) had recurrence; the median age was 61 year-old and the median lap-time 16 months. The PET PET/CT scan obtained the following results: sensitivity 96.7%, specificity 88.9%, positive predictive value 96.3%, negative predictive value 88.9%, positive likekihood ratio 8.7 and negative likelihood ratio 0.04. Discusion: The best tool to make diagnosis of colorectal cancer and its recurrence is PET­CT, however, none of these tests could make the diagnosis by themselves. It has to be confirmed by histopathologic studies plus other exams.

Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs

The single photon emission microscope (SPEM) is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT) images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl)] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD). Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s-1·MBq-1 were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging 99mTc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using 99mTc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity.

A clinical gamma camera-based pinhole collimated system for high resolution small animal SPECT imaging

The main objective of the present study was to upgrade a clinical gamma camera to obtain high resolution tomographic images of small animal organs. The system is based on a clinical gamma camera to which we have adapted a special-purpose pinhole collimator and a device for positioning and rotating the target based on a computer-controlled step motor. We developed a software tool to reconstruct the target’s three-dimensional distribution of emission from a set of planar projections, based on the maximum likelihood algorithm. We present details on the hardware and software implementation. We imaged phantoms and heart and kidneys of rats. When using pinhole collimators, the spatial resolution and sensitivity of the imaging system depend on parameters such as the detector-to-collimator and detector-to-target distances and pinhole diameter. In this study, we reached an object voxel size of 0.6 mm and spatial resolution better than 2.4 and 1.7 mm full width at half maximum when 1.5- and 1.0-mm diameter pinholes were used, respectively. Appropriate sensitivity to study the target of interest was attained in both cases. Additionally, we show that as few as 12 projections are sufficient to attain good quality reconstructions, a result that implies a significant reduction of acquisition time and opens the possibility for radiotracer dynamic studies. In conclusion, a high resolution single photon emission computed tomography (SPECT) system was developed using a commercial clinical gamma camera, allowing the acquisition of detailed volumetric images of small animal organs. This type of system has important implications for research areas such as Cardiology, Neurology or Oncology.

Methodological approaches to planar and volumetric scintigraphic imaging of small volume targets with high spatial resolution and sensitivity

Single-photon emission computed tomography (SPECT) is a non-invasive imaging technique, which provides information reporting the functional states of tissues. SPECT imaging has been used as a diagnostic tool in several human disorders and can be used in animal models of diseases for physiopathological, genomic and drug discovery studies. However, most of the experimental models used in research involve rodents, which are at least one order of magnitude smaller in linear dimensions than man. Consequently, images of targets obtained with conventional gamma-cameras and collimators have poor spatial resolution and statistical quality. We review the methodological approaches developed in recent years in order to obtain images of small targets with good spatial resolution and sensitivity. Multipinhole, coded mask- and slit-based collimators are presented as alternative approaches to improve image quality. In combination with appropriate decoding algorithms, these collimators permit a significant reduction of the time needed to register the projections used to make 3-D representations of the volumetric distribution of target’s radiotracers. Simultaneously, they can be used to minimize artifacts and blurring arising when single pinhole collimators are used. Representation images are presented, which illustrate the use of these collimators. We also comment on the use of coded masks to attain tomographic resolution with a single projection, as discussed by some investigators since their introduction to obtain near-field images. We conclude this review by showing that the use of appropriate hardware and software tools adapted to conventional gamma-cameras can be of great help in obtaining relevant functional information in experiments using small animals.

Materiales Proinflamatorios. Una Alternativa en Medicina Reparativa y Preventiva / Proinflammatory biomaterials. An alternative in repairing and preventing medicine

Una de las áreas del conocimiento humano en las que se anticipa una acelerada expansión, es el desarrollo de nuevos materiales y su aplicación en ingeniería tisular. Los materiales que han desarrollado se caracterizan por la mínima inducción de inflamación debido a que son esencialmente inertes, degradables o inductores de integración tisular. Los materiales proinflamatorios son una nueva categoría de materiales que pueden usarse para aprovechar algunas de las consecuencias del proceso inflamatorio como son la angiogénesis o la inducción de respuestas inmunes. Es posible atrapar antígenos en polímeros de neopreno y generar matrices insolubles que, dependiendo de la formulación, inducen una respuesta inflamatoria dominada por fibroblastos y angiogénesis o una reacción granulomatosa. Los sistemas de Depósito de Antígeno (SDA) son una modalidad de implante de materiales proinflamatorios en los que el antígeno es extraído, procesado y presentado al sistema inmune por células fagocíticas del huésped. La posibilidad de incorporar cualquier tipo de antígeno y modular la naturaleza de la respuesta inflamatoria e inmune que desencadena, ofrece alternativas e inmunoprofilaxis e inmunoterapia de patologías infecciosas, tumorales, alérgicas, degenerativas o autoinmunes. Finalmente, un sistema de deposito de antígeno, como el SDA neopreno, permitirá evaluar la eficiencia de implantes multiantígenos para vacunar, en una sola ocasión, contra varios tipos de microorganismos causante de enfermedad en humanos o animales...

Resonancia magnetica de las anomalias congenitas del corazon y grandes vasos / Magnetic resonance imaging of congenital cardiac anomalies and great arteries

La Resonancia Magnética ha surgido como un método confiable y eficaz para la evaluación de la patología cardíaca y de las grandes arterias. Las diferentes técnicas disponibles en el momento hacen de este examen una adecuada herramienta en el enfoque diagnóstico de los pacientes con enfermedad del sistema cardiovascular, que puede ser usada de manera complementaria a otros exámenes o de primera elección, según algunas indicaciones clínicas. En este estudio se revisan 7 casos representativos que se realizaron en nuestra institución, con anomalías congénitas cardíacas y de los grandes vasos. Se hace énfasis en la tónica del examen, así como también en los hallazgos más representativos

Evaluacion del crecimiento fetal por la medicion ultrasonica de los diametros biparietal y abdominal. / Evaluation of the fetal growth by ultrasonic measurement of the biparietal and abdominal diameters

Como parte de un programa de investigacion de fetometria en nuestro medio, se efectuo este estudio por medio de ultrasonografia con los objetivos siguientes: Incrementar la muestra y reprocesar la curva de diametro biparietal (D.B.P.) obtenida en estudios previos; elaborar tablas de normalidad del diametro abdominal (D.A.) y elaborar patrones normales de la relacion cabeza-abdomen (C-A). Individualmente la medicion del D.B.P. resulto ser mas precisa que la del D.A., sin embargo, la relacion C-A incrementa significativamente las posibilidades de evaluacion del crecimiento y del desarrollo fetal

Cierre quirurgico del conducto arterioso en recien nacidos de pretermino Cinco anos de experiencia / Surgical closure of patent ductus arteriosus in pre-term newborn infants: 5 years' experience

Se refere la experiencia de los primeros cinco anos de trabajo en la Unidad de Cuidados Intensivos Neonatales del Centro Hospitalario 20 de Noviembro del ISSSTE, en el diagnostico y tratamiento quirurgico del conducto arterioso persistente en neonatos con sindrome de dificultad respiratoria sometidos a ventilacion mecanica. Se senalan los datos clinicos para su diagnostico; la edad gestacional, peso, dia promedio en que se efectuo el diagnostico, dia promedio en que fueron sometidos a la cirugia y se comparan estos datos observando su influencia entre el grupo de supervivientes y el grupo que sufrio una defuncion temprana

Estudio de la amenorrea primaria. Durante el periodo de 4 anos 1976-1980. / Study of primary amenorrhea during a four-year period 1976-1980

Se analisan 53 pacientes con amenorrea primaria durante un periodo de 4 anos, 1976-1979, utilizando un metodo clinico deductivo, el cual creemos es de mayor utilidad practica. La frecuencia de amenorrea primaria es de un 4% en un servicio de referencia. De 53 pacientes que consultaron 44 fueron estudiadas, correspondiendo la mayor frecuencia al grupo genetico, siguiendole en su orden la causa anatomica y la endocrina. El sindrome de disgenesia gonadal pura fue la entidad clinica predominante, seguido del sindrome de Rokitansky. La tuberculosis como unica entidad adquirida presenta una frecuencia alta de 9.1%. Las pacientes con mejor pronostico en relacion a la fertilidad pertenecen al grupo de causa endocrina