Optimización de los protocolos y del uso de contrastes en tomografía computarizada de los equipos de tomografía por emisión de positrones / Optimization of the protocols for the use of contrast agents in PET/CT studies

Desde su introducción para uso clínico en 1998, la tomografía por emisión de positrones en combinación con la tomografía computarizada (PET-TC) ha supuesto un progreso en la atención de los pacientes oncológicos, desde el diagnóstico inicial, pasando por la evaluación de la respuesta al tratamiento y hasta la valoración de las posibles recidivas. El componente TC de un estudio PET-TC, además de utilizarse para obtener el factor de corrección de la atenuación, aporta información anatómica de la distribución del radiofármaco y es especialmente útil en las situaciones de falsos positivos y falsos negativos de la PET, mejorando su rendimiento diagnóstico. El uso de contraste (intravenoso u oral), así como la utilización de un componente de TC óptimo, han supuesto una mejora en la detección y la caracterización de las lesiones; no obstante, existen circunstancias en las que no está justificado su uso sistemático. La adquisición estándar de estos equipos híbridos de PET-TC es el protocolo de cuerpo entero, pero pueden producirse artefactos de imagen debido a la posición del paciente y a los movimientos respiratorios entre el tiempo de realización de la TC y de adquisición de la PET. El objetivo del presente artículo es abordar estos aspectos desde una perspectiva constructiva, en un intento de maximizar el potencial diagnóstico de la PET-TC para ofrecer una mejor atención a los pacientes (AU)

The introduction of PET/CT scanners in clinical practice in 1998 has improved care for oncologic patients throughout the clinical pathway, from the initial diagnosis of disease through the evaluation of the response to treatment to screening for possible recurrence. The CT component of a PET/CT study is used to correct the attenuation of PET studies; CT also provides anatomic information about the distribution of the radiotracer. CT is especially useful in situations where PET alone can lead to false positives and false negatives, and CT thereby improves the diagnostic performance of PET. The use of intravenous or oral contrast agents and optimal CT protocols have improved the detection and characterization of lesions. However, there are circumstances in which the systematic use of contrast agents is not justified. The standard acquisition in PET/CT scanners is the whole body protocol, but this can lead to artifacts due to the position of patients and respiratory movements between the CT and PET acquisitions. This article discusses these aspects from a constructive perspective with the aim of maximizing the diagnostic potential of PET/CT and providing better care for patients (AU)

Optimization of the protocols for the use of contrast agents in PET/CT studies. / Optimización de los protocolos y del uso de contrastes en tomografía computarizada de los equipos de tomografía por emisión de positrones.

The introduction of PET/CT scanners in clinical practice in 1998 has improved care for oncologic patients throughout the clinical pathway, from the initial diagnosis of disease through the evaluation of the response to treatment to screening for possible recurrence. The CT component of a PET/CT study is used to correct the attenuation of PET studies; CT also provides anatomic information about the distribution of the radiotracer. CT is especially useful in situations where PET alone can lead to false positives and false negatives, and CT thereby improves the diagnostic performance of PET. The use of intravenous or oral contrast agents and optimal CT protocols have improved the detection and characterization of lesions. However, there are circumstances in which the systematic use of contrast agents is not justified. The standard acquisition in PET/CT scanners is the whole body protocol, but this can lead to artifacts due to the position of patients and respiratory movements between the CT and PET acquisitions. This article discusses these aspects from a constructive perspective with the aim of maximizing the diagnostic potential of PET/CT and providing better care for patients.

Tomografía por emisión de positrones/resonancia magnética: presente y futuro / Positron emission tomography/magnetic resonance: present and future

La PET/RM fue introducida al mercado recientemente tras muchos años de investigación y desarrollo. La simple idea de combinar la capacidad molecular de la PET y sus diversos radiotrazadores con la excelente resolución tisular de la RM y la amplia gama de técnicas multiparamétricas que esta posee generan mucha expectación sobre los posibles usos de esta tecnología. Existen muchos desafíos que hay que resolver, pero el más urgente es la derivación del mapa de atenuación de las secuencias de RM; especialmente porque la PET/TC ya ha demostrado en su corta existencia un gran impacto clínico en oncología, neurología y cardiología. A pesar de estas dificultades, la experimentación clínica se está desarrollando de manera acelerada con el afán de encontrar aquellas áreas donde la PET/RM demuestre superioridad sobre los métodos de imagen existentes. En las pocas publicaciones iniciales hasta la fecha que analizan su papel clínico se describen áreas en donde la migración de la PET/TC hacia la PET/RM se realiza aunque sea solo para eliminar la radiación de la TC. Sin embargo, son muchas las aplicaciones teóricas que la PET/RM podría aportar al campo del diagnóstico por imágenes. En esta revisión haremos un repaso de ellas, la evidencia existente en RM y PET que avalan esas premisas y lo que nuestra experiencia con un equipo de PET/RM nos ha enseñado en el corto periodo de un año(AU)

PET/MRI has recently been introduced onto the market after several years of research and development. The simple notion of combining the molecular capabilities of the PET and its difference available radiotracers with the excellent tissue resolution of the MRI and wide range of multiparametric imaging techniques has generated great expectations upon the possible uses of this technology. Many challenges must be worked out. However, the most urgent one is the derivation of the MRI-based attenuation correction map. This is especially true because the PET/CT has already demonstrated a huge clinical impact within oncology, neurology and cardiology during its short existence. Despite these difficulties, research is being carried out at a rapid pace in the clinical setting in order to find areas in which the PET/MRI is superior to other existing imaging modalities. In the few initial publications found up to date that have analyzed its clinical role, areas have been identified where PET/CT can migrate to PET/MRI, even if only to suppress the CT scan's ionizing radiation. Nonetheless, there are many theoretical applications in which the PET/MRI can further improve the field of diagnostic imaging. In this article, we will review those applications, the evidence existing regarding the MRI and PET that support those premises as well as that which we have learned in the short period of one year with our experience using the PET/MRI(AU)

[Positron emission tomography/magnetic resonance: Present and future]. / Tomografía por emisión de positrones/resonancia magnética: presente y futuro.

PET/MRI has recently been introduced onto the market after several years of research and development. The simple notion of combining the molecular capabilities of the PET and its difference available radiotracers with the excellent tissue resolution of the MRI and wide range of multiparametric imaging techniques has generated great expectations upon the possible uses of this technology. Many challenges must be worked out. However, the most urgent one is the derivation of the MRI-based attenuation correction map. This is especially true because the PET/CT has already demonstrated a huge clinical impact within oncology, neurology and cardiology during its short existence. Despite these difficulties, research is being carried out at a rapid pace in the clinical setting in order to find areas in which the PET/MRI is superior to other existing imaging modalities. In the few initial publications found up to date that have analyzed its clinical role, areas have been identified where PET/CT can migrate to PET/MRI, even if only to suppress the CT scan's ionizing radiation. Nonetheless, there are many theoretical applications in which the PET/MRI can further improve the field of diagnostic imaging. In this article, we will review those applications, the evidence existing regarding the MRI and PET that support those premises as well as that which we have learned in the short period of one year with our experience using the PET/MRI.

Esplenosis abdominal: una entidad frecuentemente infradiagnosticada / Abdominal splenosis: an often underdiagnosed entity

La esplenosis se define como el autotrasplante heterotópico de tejido esplénico como resultado de una rotura del bazo por trauma o cirugía. Es una condición benigna y de hallazgo casual, aunque en ciertas ocasiones las pruebas de imagen puedan orientar a malignidad simulando tumores renales, linfomas abdominales y endometriosis, entre otros. Presentamos el caso de un varón de 42 años al que, tras un estudio por dolor abdominal, se le realiza una resonancia magnética en la que se observan múltiples adenopatías en el abdomen que pueden orientar a un síndrome linfoproliferativo. Como antecedente importante, presenta esplenectomía por trauma abdominal a los 9 años. Tras varios estudios, se decide realizar una gammagrafía con hematíes desnaturalizados marcados con tecnecio-99m que muestra múltiples depósitos patológicos distribuidos por todo el abdomen e, incluso, la pelvis, siendo este hallazgo compatible con esplenosis(AU)

Splenosis is defined as the heterotopic autotransplantation of splenic tissue because of a ruptured spleen due to trauma or surgery. It is a benign and incidental finding, although imaging tests may sometimes orient toward malignancy simulating renal tumors, abdominal lymphomas, endometriosis, among other. We report the case of a 42-year old male in whom a MRI was performed after a study due to abdominal pain. Multiple enlarged lymph nodes were observed in the abdomen, suggestive of lymphoproliferative disease. As an important background, splenectomy was carried out due to abdominal trauma at age 9. After several studies, it was decided to perform a 99mTc-labeled heat-damaged red blood cell scintigraphy that showed multiple pathological deposits distributed throughout the abdomen, and even the pelvis, being consistent with splenosis(AU)

[Abdominal splenosis: an often underdiagnosed entity]. / Esplenosis abdominal: una entidad frecuentemente infradiagnosticada.

Splenosis is defined as the heterotopic autotransplantation of splenic tissue because of a ruptured spleen due to trauma or surgery. It is a benign and incidental finding, although imaging tests may sometimes orient toward malignancy simulating renal tumors, abdominal lymphomas, endometriosis, among other. We report the case of a 42-year old male in whom a MRI was performed after a study due to abdominal pain. Multiple enlarged lymph nodes were observed in the abdomen, suggestive of lymphoproliferative disease. As an important background, splenectomy was carried out due to abdominal trauma at age 9. After several studies, it was decided to perform a (99m)Tc-labeled heat-damaged red blood cell scintigraphy that showed multiple pathological deposits distributed throughout the abdomen, and even the pelvis, being consistent with splenosis.