PET-CT FDG en el diagnóstico y seguimiento de vasculitis de grandes vasos / Positron emission tomography-CT scan (PET-CT) in the diagnosis of large vessel vasculitis

Vasculitides are a broad group of diseases that can involve any kind of vessel in any organ. These can be classified according to the size of the affected vessels. The most used classification categorizes them in small, medium, and large vessel vasculitis. Large vessel vasculitis can be further divided in Takayasu arteritis and giant cell arteritis which can sometimes be indistinguishable, even with biopsy. Radiology plays an important role identifying distribution patterns and disease extension18. Fluorine-Fluorodeoxyglucose (FDG) PET-CT shows increased vessel wall FDG uptake in patients with active large vessel vasculitis. Multiple studies show that FDG PET-CT helps to identify the anatomic structures with the disease, as well as evaluate its progression with a high sensibility and specificity in non-treated patients with large vessel vasculitis.

Actualización en el uso del PET/CT en sarcoma de Ewing, a propósito de un caso

The use of positron emission tomography with computed tomography (PET/CT) for adult cancer patients is widespread, however, its use in pediatric patients is limited by fear of radiation, monetary cost and lack of awareness of its greater sensitivity in the evaluation of some types of tumors. Ewing's sarcoma is one of the primary pediatric malignancies in which PET/CT with 18F-labeled fluorodeoxyglucose (18F-FDG) has demonstrated greater sensitivity in the evaluation of bone metastases compared to scintigraphy, as well as in the evaluation of treatment response. We report a 13 years old female consulting for retrosternal pain. A chest CT scan showed an infiltrating mass originating in the sternum. A biopsy confirmed the presence of an Ewing sarcoma. The tumor was staged with PET/CT which showed multiple bone lesions not visible in previous studies.

¿Cuándo solicitar PET/CT en la evaluación de sarcoidosis? / When should a PET/CT be requested in sarcoidosis?

Sarcoidosis is a multisystemic disease of variable course that mainly affects thoracic lymph nodes and lung parenchyma. However, any organ can be involved. There is no single test for the definitive diagnosis or a precise method to evaluate the course of the disease. PET/CT is not included in the standard workup for sarcoidosis, but it may assess the inflammatory activity, detect extrapulmonary disease such as cardiac involvement and evaluate the response to treatment. It is important to be aware of the optimal timing to request a PET/CT in sarcoidosis and which patients would benefit with this procedure.

Concordancia Interobservador para la Validación del PI-RADS v2 / Interobserver Agreement for the PI-RADS v2 Validation

Objetivo Evaluar la variabilidad interobservador en el uso de la versión 2.0 del PI- RADS (PI-RADS v2), en lectores experimentados y no experimentados. Materiales y Métodos Estudio retrospectivo de análisis de concordancia de lectores. Entre enero de 2015 y diciembre de 2016, 1.656 sujetos fueron estudiados mediante resonancia magnética multiparamétrica (RMmp) de próstata en nuestra institución. Se estimó la distribución porcentual del reporte en categoría PI-RADS v2, y con esa información, se realizó una selección de 150 casos con esquema de aleatorización estratificada a las distribuciones porcentuales de cada categoría. Dichos casos fueron anonimizados, presentados a tres lectores con cinco, cuatro y dos años de experiencia en lectura de RMmp además de tener más de un año de experiencia en el uso del PI- RADS v2 siendo leídos en forma individual. Los datos resultantes fueron analizados en forma independiente por un cuarto investigador. Resultados El valor de kappa ponderado para los observadores fue de 0,69 (IC 95: 0,64 a 0,75). La mayor concordancia correspondió a los lectores de mayor experiencia, donde alcanza un valor de 0,72 (IC 95%: 0,69 a 0,76). La concordancia entre los valores PI-RADS que determinan seguimiento o bien una intervención de acuerdo a elementos clínicos (1-2-3) y conducta activa (4-5) correspondió a 0,70 (IC 95%: 0,59 a 0,78). Discusión Se logró demostrar un acuerdo sustancial entre radiólogos utilizando el PI- RADS v2 para la detección en RMmp de lesiones sospechosas, mayor entre los dos lectores más experimentados. Sin embargo, la comparación del lector de menor experiencia con los de mayor experiencia también presentó una importante concordancia. Los valores de concordancia entre observadores para PI-RADS 2:4 fueron similares a los reportados en la literatura. Conclusiones El PI-RADSv2 ha demostrado en nuestro centro, con radiólogos dedicados a imágenes de abdomen y estudios de próstata, un alto nivel de acuerdo en la interpretación de la RMmp de próstata, encontrándose a tono con lo reportado en la literatura.

Purpose To evaluate the interobserver variability in the use of the PI-RADS 2.0 version, in experienced and non-experienced readers. Material and Methods Retrospective studyof readers' concordance analysis. Between January 2015 and December 2016, 1656 subjects were studied through multiparametric MRI (RMmp) of prostate in our institution. The percentage distribution of the report was estimated in each PI-RADS category, and a selection of 150 cases with a stratified randomization scheme was made to the percentage distributions of every category. These cases were anonymized, presented to three readers with 5, 4 and 2 years' experience in reading RMmp, and more than one-year experience with PI-RADS v2, and were read individually. The resulting data were analyzed independently by a fourth investigator. Results The weighted kappa value for the observers was 0.69 (IC 95: 0.64 to 0.75). The highest agreement corresponded to the two most experienced readers, where it reached a value of 0.72 (95% CI: 0.69 to 0.76). The concordance between the PI-RADS values that determine follow-up (1-2-3) and active behavior (4-5) corresponded to 0.70 (95% CI: 0.59 to 0.78). Discussion It was possible to demonstrate a substantial agreement between radiologists using the PI-RADS v2 for the detection in RMmp of suspicious lesions, greater among the two most experienced readers. However, the comparison of the less experienced reader with those of greater experience also presented an important concordance. The inter-observer concordance values for PI-RADS 2:4 were like those reported in the literature. Conclusions The PI-RADS v2 has demonstrated, in our center, with radiologists dedicated to abdominal images and prostate studies, a high level of agreement in the interpretation of prostate MRmp.

Abdomen agudo en el embarazo: evaluación por resonancia magnética / Acute abdomen in pregnancy: magnetic resonance evaluation

Acute abdominal pain in pregnant patients is a common reason for emergency consultation. Diagnosis is particularly difficult because of misleading factors related to normal pregnancy. Ultrasonography (US) in the evaluation of these patients is the first choice; the absence of radiation and side effects to the fetus allow its use without contraindications. However, the evaluation is limited by the normal anatomy alterations due to the displacement of the intra-abdominal structures, requiring greater skill of the operator and results are often uncertain. Given this scenario Magnetic Resonance Imaging (MRI) plays an increasingly important role, the absence of ionizing radiation and evidence of fetal harm, has allowed it to be incorporated as a tool when there is diagnostic uncertainly. This becomes especially important in suspected surgical pathology, acute appendicitis being one of the most common. MRI enables its identification as well as its differential diagnoses.

En las pacientes gestantes el dolor abdominal agudo es motivo común de consulta de urgencia. Su diagnóstico es particularmente difícil debido a factores confundentes relacionados al embarazo normal. La ultrasonografía (US) en la evaluación de estas pacientes es de primera línea; la ausencia de radiación y efectos secundarios en el feto permiten su uso sin contraindicaciones. Sin embargo, la evaluación se ve limitada por la alteración de la anatomía habitual debido al desplazamiento de las estructuras intra-abdominales, requiriendo mayor destreza del operador y resultados frecuentemente inciertos. Ante este escenario la resonancia magnética (RM) juega un rol de importancia creciente, la ausencia de radiación ionizante y de evidencias de daño fetal, han permitido incorporarla como herramienta ante dudas diagnósticas. Este hecho adquiere especial importancia en la sospecha de patología quirúrgica, siendo la apendicitis aguda una de las más frecuente. La RM permite reconocerla así como también a sus diagnósticos diferenciales.