Arteritis de Takayasu como hallazgo incidental en un paciente con enfermedad celiaca: la importancia de la tomografía computarizada por emisión de positrones / Takayasu's arteritis as an incidental finding in a patient with celiac disease: the importance of positron emission computed tomography

Resumen Introducción: La arteritis de Takayasu es una vasculitis de grandes vasos que afecta a las arterias elásticas de gran calibre, fundamentalmente la aorta y sus ramas principales. Ocurre frecuentemente en mujeres entre los 20-30 años, por lo que es muy infrecuente en la edad pediátrica. Caso clínico: Se presenta el caso de una paciente de 15 años en seguimiento desde los 9 años por enfermedad celiaca. A los 13 años se detectó anemia de trastornos crónicos, elevación de proteína C reactiva y velocidad de sedimentación globular. La paciente permaneció en todo momento asintomática. Tras descartar otros procesos, se solicitó tomografía computarizada por emisión de positrones (PET-TC), donde se detectaron lesiones compatibles con vasculitis de grandes vasos. La valoración por Cardiología evidenció un aneurisma en coronaria derecha. Se realizó angio-TC, que sugirió arteritis de Takayasu tipo III. Conclusiones: Es frecuente un retraso en el diagnóstico de la arteritis de Takayasu en los pacientes pediátricos. En este caso se encontraron lesiones de la fase II sin la presencia de síntomas correspondientes a la fase I. El PET-TC permitió el diagnóstico de vasculitis, clave para el diagnóstico de la paciente.

Abstract Background: Takayasu arteritis is a large-vessel vasculitis which affects large-caliber elastic arteries, primarily the aorta and its main branches. It mainly affects women between 20-30 years, so it is rare in children. Case report: We describe the case of a 15-year-old female who was followed up since she was 9 years old due to celiac disease. At the age of 13, anaemia of chronic disorders associated to elevated C-reactive protein and erythrocyte sedimentation were detected. The patient remained asymptomatic. After excluding other diseases, we requested a positron emission computed tomography (PET-CT); lesions compatible with large-vessel vasculitis were detected. Cardiology evaluation showed an aneurysm in the right coronary artery. Angio-CT suggested Takayasu type III arteritis. Conclusions: The delay in the diagnosis of Takayasu arteritis in pediatric patients is quite common. In this case, we have found phase II lesions, with no previous phase I symptoms. However, PET-CT allowed the diagnosis of vasculitis, key to the diagnosis of the patient.

Estudio preclínico en primate no-humano con [18F]Fluorotimidina. dosimetría y biodistribución / [18F]Fluorothymidine preclinical study in non-human primate. Dosimetry and biodistribution

Resumen En el linfoma Hodgkin, la tomografía por emisión de positrones (PET-TC) forma parte de los nuevos algoritmos diagnósticos y de valoración de respuesta al tratamiento como método eficaz para evaluar supervivencia y pronóstico de la enfermedad, ya sea a través del PET-TC interino con 2-[18F]fluoro- 2-desoxi-D-glucosa, ([18F]FDG), como también del PET-TC al final de la terapéutica. Sin embargo, la [18F]FDG presenta una baja especificidad en linfoma no Hodgkin de grandes células B. Ante la aprobación en nuestro país del radiotrazador 3´-desoxi-3´-[18F]fluorotimidina, [18F]FLT, indicador de proliferación celular de fase S, éste resultaría un prometedor radiofármaco de uso diagnóstico frente a [18F]FDG. Por lo tanto, el objetivo de este estudio fue valorar la utilización de [18F]FLT mediante un modelo animal en primates no humanos Sapajus cay. Se obtuvieron imágenes de cuerpo entero para evaluar la biodistribución y realizar un cálculo dosimétrico en la médula ósea, dado que este es un órgano crítico por la permanencia del radiofármaco. Para órganos de inte rés, se trazaron curvas de actividad en función del tiempo y se calculó la actividad acumulada normalizada. La dosis media absorbida en la médula ósea se determinó aplicando el esquema conocido como Medical Internal Radiation Dosimetry (MIRD). La dosis media obtenida en el modelo animal por unidad de actividad administrada fue de 8.7 μGy/MBq. Este resultado se extrapoló a un modelo humano adulto resultando en 32 μGy/MBq, de lo que se desprende que PET-TC con [18F]FLT es una herramienta segura para uso diagnóstico y de seguimiento en pacientes con enfermedad oncológica linfoproliferativa u otros tumores sólidos.

Abstract Positron emission tomography-computed tomography (PET-CT) is part of the new diagnostic and therapeutic algorithms for Hodgkin lymphoma. PET-CT is a valuable tool for the assessment of treatment response and prognosis, both by means of interim PET-CT with 2-[ 18F]fluoro-2-deoxy-D-glucose ([18F]FDG) as well as end of treatment (EOT) PET-CT. Given the low specificity of [ 18F]FDG for the diffuse large B cell lymphoma (DLBCL), there is an emerging need for a more specific radiopharmaceutical agent. The recent approval of the radiotracer 3´-deoxy-[18F]-3´-flourothymidine ([18F]FLT), a phase-S mitosis cell proliferation marker, for clinical application in our country, shows as a promising radiopharmaceutical for diagnostic use with incremental value over [18F]FDG. In this study, non-human primates (Sapajus cay) were studied. PET-CT study was performed after the injection of [18F]FLT. Whole-body images were obtained to evaluate the biodistribution and to calculate the dosimetry of bone marrow, as this is a critic organ to this radiotracer. Time-activity curves were traced, normalized activity uptake of the organs of interest were calculated, and mean absorbed dose was also calculated using the established Medical Internal Radiation Dosimetry (MIRD) scheme. The mean dose obtained in the animal model per unit of activity administered was 8.7 μGy/MBq. This result was extrapolated to an adult human model resulting in 32 μGy/MBq, thereby suggesting that [18F]FLT is a secure diagnostic tool to be used on the tracing of patients with DLBCL.

Prognostic value of 18F-FDG PET/CT parameters and histopathologic variables in head and neck cancer / Valor prognóstico de parâmetros de PET/TC com 18F-FDG e variáveis histopatológicas em câncer de cabeça e pescoço

Abstract Introduction 18F-fluorodeoxyglucose positron emission tomography/computed tomography parameters such as; maximum standardized uptake values, standard metabolic tumor volume and otal lesion glycosis are important prognostic biomarkers in cancers. Objective To investigate the prognostic value of these parameters in patients with head and neck cancers. Methods We performed a retrospective study including 47 patients with head and neck cancer who underwent18F-fluorodeoxyglucose positron emission tomography/computed tomography prior to treatment. Standard metabolic tumor volume, otal lesion glycosis and standardized uptake were measured for each patient. The prognostic value of quantitative 18F-fluorodeoxyglucose positron emission tomography/computed tomography parameters and clinicopathologic variables on disease free survival and overall survival were analyzed. Results The median (range) standard metabolic tumor volume and otal lesion glycosis and standardized uptake were 7.63 cm3 (0.6-34.3), 68.9 g (2.58-524.5 g), 13.89 (4.89-33.03 g/mL), respectively. Lymph node metastases and tumour differentiation were significant variables for disease free survival and overall survival, however, all 18F-fluorodeoxyglucose positron emission tomography/computed tomography parameters were not associated with disease- free survival and overall survival. Conclusion Pretreatment quantities positron emission tomography parameters did not predict survival in head and neck cancer.

Resumo Introdução Os parâmetros da tomografia por emissão de pósitrons/tomografia computadorizada com 18F-fluordesoxiglicose, como os máximos valores de captação padronizados, o volume metabólico tumoral padrão e a glicólise total da lesão são importantes biomarcadores prognósticos de câncer. Objetivo Investigar o valor prognóstico desses parâmetros em pacientes com câncer de cabeça e pescoço. Método Fizemos um estudo retrospectivo que incluiu 47 pacientes com câncer de cabeça e pescoço e que foram submetidos à tomografia por emissão de pósitrons/tomografia computadorizada com 18F-fluordesoxiglicose antes do tratamento. Volume metabólico tumoral, glicólise total da lesão e valores de captação padronizados foram aferidos em cada paciente. O valor prognóstico de parâmetros quantitativos da tomografia por emissão de pósitrons/tomografia computadorizada com 18F-fluordesoxiglicose e das variáveis clínico-patológicas sobre a sobrevida livre de doença e a sobrevida geral foi analisado. Resultados A média (intervalo) de volume metabólico tumoral e glicólise total da lesão e valores de captação padronizados foram 7,63 cm3 (0,6-34,3), 68,9 g (2,58-524,5) e 13,89 g/mL (4,89-33,03), respectivamente. Metástase nos nódulos linfáticos e diferenciação tumoral foram variáveis significativas de sobrevida livre de doença e sobrevida geral; contudo, nenhum parâmetro da tomografia por emissão de pósitrons/tomografia computadorizada com 18F-fluordesoxiglicose estava associado a sobrevida livre de doença e sobrevida geral. Conclusão As quantidades dos parâmetros da tomografia por emissão de pósitrons pré-tratamento não previram a sobrevida em câncer de cabeça e pescoço.

Hipoglucemia hiperinsulinémica congénita persistente, reporte de un caso / Persistent congenital hyperinsulinemic hypoglucemia, case report

Resumen La placenta y el hígado son los encargados del metabolismo de los carbohidratos. La glucosa es fundamental para el metabolismo cerebral. La hipoglucemia se define con valores < 47 mg/dl. La hipoglicemia que persiste más de 7 días se atribuye a problemas metabólicos o endocrinológicos y requiere un flujo de glucosa > 12 mg/kg/min para alcanzar normo-glicemia. La hipoglicemia hiperinsulinémica congénita persistente (HHCP) es poco común (1:50,000 nacidos vivos), es la causa más común de hipoglicemia persistente secundaria a una secreción inadecuada de insulina, que puede afectar el neurodesarrollo. Hay una forma difusa y una focal, con manifestaciones clínicas idénticas, pero con mecanismos patológicos diferentes. El tratamiento médico es a base de diazóxido y ocreótide. En el 95% de los casos no hay respuesta al tratamiento médico, requiriendo pancreatectomía subtotal. Se utilizó ocreótide y nifedipino. La tomografía computada con emisión de positrones (PET/TC 18F-DOPA) encontró incremento en la capación pancreática de insulina, se realizó pancreactectomía. Se egresó sin complicaciones y en seguimiento pediátrico sin alteraciones neurológicas.

Abstract The placenta and liver are responsible for the metabolism of carbohydrates. The glucose is fundamental for brain metabolism. Hypoglycaemia is defined as values < 47 mg/dl. Hypoglycaemia that persists for more than 7 days is attributed to metabolic or endocrine problems and requires glucose flow > 12 GKM to reach normoglycemia. Persistent congenital hyperinsulinemic hypoglycemia (PCHH) is uncommon (1:50,000 live births) is the most common cause of persistent hypoglycemia secondary to inadequate insulin secretion, can significantly affect neurodevelopment. There is a diffuse and a focal form, with identical clinical manifestations, but with different pathological mechanisms. The medical treatment is diazoxide and ocreotide. In 95% of cases there is no response to medical treatment, requiring subtotal pancreatectomy. Ocreotide and nifedipine were used. Positron emission computed tomography (PET/CT 18F-DOPA) found an increase in pancreatic insulin capacity, a pancreactectomy was performed. He was discharged without complications and in pediatric follow-up without neurological alterations.

Utilidad de la 18f-colina pet/tc en hiperparatiroidismo primario persistente o recurrente: experiencia inicial / Usefulness of 18f-choline pet / tc in persistent or recurrent primary hyperparathyroidism: initial experience

El hiperparatiroidismo persistente/recurrente representa un desafío en la localización del tejido paratiroideo hiperfuncionante. En esta subpoblación, los métodos convencionales ofrecen un menor rédito diagnóstico. La 18F-colina PET/TC podría ser una buena alternativa dada su mejor resolución espacial, capacidad de detectar glándulas ectópicas y la conjunción de la imagen molecular y anatómica. Sin embargo, la evidencia en este subgrupo de pacientes es escasa. Objetivo: evaluar la utilidad de la 18F-colina PET/TC como método de localización en el hiperparatiroidismo persistente o recurrente. Materiales y métodos: se analizaron los pacientes con 18F-colina PET/TC para hiperparatiroidismo entre diciembre de 2015 y enero de 2018 en un centro terciario de alto volumen. Se analizaron el número de lesiones, su localización, tamaño y el Standard Uptake Value máximo (SUV max) en las imágenes tempranas y tardías. Se compararon los resultados con los métodos convencionales. Resultados: 7 de 15 pacientes habían sido operados previamente (persistentes/recurrentes). La 18F-colina PET/TC detectó 6/7 casos (83,33%), la ecografía cervical 1/4 (25%) y el SPECT de paratiroides y la resonancia nuclear magnética 2/5 (40%). El SUV max obtenido fue variable, en la mitad de los casos a los 10 minutos y en los restantes a la hora; el tamaño promedio de las lesiones fue 8,61 mm (6-12 mm). Conclusiones: la 18F-colina PET/TC muestra una alta tasa de detección en los pacientes con hiperparatiroidismo persistente/recurrente. La combinación del comportamiento biológico del PET con los hallazgos morfológicos aportados por la TC con contraste endovenoso le ofrecería ventajas sobre otros estudios que podrían posicionarlo como método de primera línea en esta subpoblación. (AU)

Persistent or recurrent hyperparathyroidism represents a challenge regarding the localization of the hyper-functioning parathyroid tissue. In this subpopulation of hyperpharathyroid patients, conventional methods have a low diagnostic yield. The 18F-choline PET /CT could be a good alternative given its better spatial resolution, ability to detect ectopic glands, and the conjunction of the molecular and anatomical image. However, the evidence in this subgroup of patients is limited. Objective: to evaluate the utility of 18F-choline PET/ CT as a localization method in persistent or recurrent hyperparathyroidism. Materials and methods: patients with 18F-choline PET / CT for hyperparathyroidism between December 2015 and January 2018 in a high-volume tertiary center were included. The number of lesions, and their location, size, and maximum Standard Uptake Value (SUV) in the early and late images were analyzed. The results were compared to conventional methods. Results: 7 of 15 patients had been previously operated (persistent/recurrent). 18F-choline PET / CT detected 6/7 cases (83,33%), cervical ultrasound 1/4 (25%) and parathyroid SPECT and magnetic resonance 2/5 (40%). The maximum SUV was variable, one half at 10 minutes and the other half at 60 minutes; the average size of the lesions was 8.61 mm (6-12 mm). Conclusions: 18F-Choline PET / CT shows a high detection rate in patients with persistent / recurrent hyperparathyroidism. The combination of the biological behavior of PET with the morphological findings provided by CT with intravenous contrast would offer advantages over other studies that could position it as a first line method in this subpopulation. (AU)

Hallazgo de Tumor Maligno/Premaligno Insospechado en Estudios 18 F-FDG PET/TC en Pacientes Oncológicos: Incidental Malignant/Premalignant Tumor Detection in Oncological Patients / 18 f-fdg pet/ct

Objetivo Determinar la frecuencia y el tipo de tumor maligno/premaligno insospechado como hallazgo en estudios 18 F-FDG PET/TC en pacientes oncológicos. Material y Métodos Se revisaron retrospectivamente (de enero de 2014 a marzo de 2017), informes de estudios 18 F-FDG PET/TC de pacientes oncológicos, identificando aquellos pacientes con hallazgo de lesión sospechosa de otro tumor maligno como hallazgo incidental. La información fue obtenida a partir de determinadas "palabras clave" en la base de datos del Centro. Los hallazgos se confirmaron mediante histopatología y/o seguimiento clínico y paraclínico de como mínimo seis meses. Resultados De 4.086 pacientes oncológicos estudiados con 18 F-FDG PET/TC, se encontró lesión sospechosa de otro tumor maligno en 130 (3,2%), de los cuales 72 eran mujeres y 58 hombres, con edad media de 61 años. Los tumores primarios más frecuentes (aquellos que motivaron el pedido del examen PET/CT inicialmente), fueron de mama (n = 27), pulmón (n = 27) y colo-recto (n = 20). Se confirmaron por histopatología 49 (1,2%) nuevos tumores malignos/premalignos y dos lesiones metastásicas. La localización del segundo tumor primario correspondió a: colon (n = 18), pulmón (n = 6), mama (n = 6), linfoma (n = 3), ovario (n = 2), endometrio/cuello uterino (n = 2), tiroides (n = 2) y otros (n = 10). Resultaron 28 hallazgos falsos positivos, 31 pacientes no se estudiaron por progresión lesional y 20 pacientes se perdieron de seguimiento. Discusión La prevalencia de neoplasia primaria maligna múltiple (NPMM) es variable entre 0,7 y 11,7%. En nuestra serie, se encontró lesión sospechosa de segundo tumor en 130 casos (3,2%), de los cuales se confirmaron 49 segundos tumores (1,2%), similar a Conclusiones La tasa de detección de tumor maligno insospechado confirmado histológicamente fue de 1,2%. Todo hallazgo incidental sospechoso de malignidad en 18 F-FDG PET/TC debe ser estudiado, ya que puede corresponder a un segundo tumor maligno no sospechado con posibilidad de tratamiento curativo.

Purpose To determine the frequency and type of unexpected malignant/ premalignant tumor as a finding in 18 F-FDG PET/CT studies in oncological patients. Material and Methods Reports of 18 F-FDG PET/CT studies of oncological patients were reviewed retrospectively (from January 2014 to March 2017), with the finding of suspicious lesion of another malignant tumor. The information was obtained from certain "keywords" in the Center's database. The findings were confirmed by histopathology when possible and with clinical and paraclinical follow-up for at least six months. Results Of 4086 oncological patients, studied with 18 F-FDG PET/CT, a suspicious lesion of another malignant tumor was found in 130 (3.2%), 72 female and 58 male sex, average age 61 years. The most frequent primary tumors were: breast (n = 27), lung (n = 27) and colo-rectum (n = 20). 49 (1.2%) new malignant/premalignant tumors and two metastatic lesions were confirmed by histopathology. The location of the second primary tumor was: colon (n = 18), lung (n = 6), breast (n = 6), lymphoma (n = 3), ovary (n = 2), endometrium/cervix (n = 2), thyroid (n = 2) and others (n = 10). There were 28 false positive findings, 31 patients were not studied for progression and 20 patients were lost to follow-up. Discussion The prevalence of multiple malignant primary neoplasia (MMPN) is variable between 0.7 and 11.7%. In our series, a suspicious second tumor lesion was found in 130 cases (3.2%), of which 49 second tumors (1.2%) were confirmed, similar to that reported by other authors. Conclusions The detection rate of unsuspected malignant tumor was 1.2%, coincident with the literature. Any incidental finding suspicious of malignancy in 18 F-FDG PET/CT should be studied since in most cases it corresponds to early diagnosis with the possibility of curative treatment.

Carcinoma del uraco / Urachal Carcinoma

Objetivo Revisar la patología tumoral del uraco, haciendo énfasis en su clínica, los métodos diagnósticos empleados y el manejo terapéutico. Métodos Presentamos el caso de un varón de 39 años con carcinoma del uraco que simuló clínicamente un absceso umbilical. Resultados Los hallazgos en la TC fueron sospechosos de patología del uraco. El examen anatomopatológico reveló células atípicas y la PET-TC demostró extensión a pared abdominal y epiplón, requiriéndose la resección completa. Conclusiones El carcinoma del uraco es una neoplasia muy poco frecuente, que tiene su origen en el epitelio que recubre la luz del uraco, un vestigio de la alantoides que conecta la vejiga con el ombligo y normalmente involuciona en la etapa embrionaria. La clínica insidiosa hace que el diagnóstico sea tardío y el pronóstico pobre. Las pruebas de imagen tienen un papel fundamental en su sospecha, así como en la definición de la relación con la pared vesical y posible extensión local o a distancia. Una vez confirmado el diagnóstico histológicamente, está indicada la resección quirúrgica completa.

Objective To review tumoral pathology of urachus, emphasizing its clinical manifestations, diagnostic methods and therapeutic management. Method We present the case of a 39-year-old male with urachal carcinoma who clinically mimicked an umbilical abscess. Result CT findings were suspected of urachus pathology. Histologic analysis of the resected specimen demonstrated atypical cells, and PET-CT showed extension to the abdominal wall and omentum, requiring complete resection. Conclusions Urachal carcinoma is a very rare neoplasm that originates in the epithelium that covers the lumen of the urachus, a vestige of the allantois that connects the bladder with the navel and normally involves in the embryonic stage. The insidious clinic makes late diagnosis and poor prognosis. Imaging tests play a fundamental role in their suspicion, as well as in the definition of the relationship with the bladder wall and possible local or distant extension. Once the diagnosis has been confirmed histologically, complete surgical resection is indicated.

PET-TC, rol y fundamentos de su uso en la especialidad de otorrinolaringología y cirugía de cabeza y cuello / PET-CT, role and fundamentals of its use in the specialty of otolaryngology and head and neck surgery

RESUMEN El PET-TC es un examen de alto costo y que expone a los pacientes a altas dosis de radiación comparado con las imágenes que habitualmente solicitamos, es por esto que hemos revisado la literatura, explicamos las bases de este tipo de examen, los rendimientos esperados, falsos positivos y negativos, asi como las recomendaciones internacionales para su correcto uso en los pacientes con cáncer de cabeza y cuello.

ABSTRACT The PET-CT is a high cost test that exposes patients to high doses of radiation compared to the images that we usually request, this is why we have reviewed the literature, we explain the bases of this type of examination, the expected, false positive and negative results, as well as international recommendations for its correct use in patients with head and neck cancer.

Custo-efetividade do uso da tomografia de emissão de pósitrons na detecção de recorrência do câncer diferenciado de tireoide / Cost-effectiveness of the use of positron emission tomography in the detection of recurrence of differentiated thyroid cancer

Avaliou-se a custo-efetividade da adição da tomografia de emissão de pósitrons (18FDG-PET-TC) aos métodos convencionais na detecção de recorrência de cânceres diferenciados de tireoide. O modelo analítico de decisão representou coorte hipotética de pacientes adultos, de alto risco pela estratificação inicial, submetidos a tireoidectomia total e ablação com I131. A estratégia convencional de detecção foi comparada à adição da 18FDG-PET-TC aplicada aos indivíduos com resultados de cintigrafia com I131 negativos. O horizonte temporal foi de dez anos. Utilizou-se a perspectiva do Sistema Único de Saúde (SUS) e, como medida de efetividade, os casos adicionais diagnosticados pela inclusão da PET-TC. Foram considerados apenas os custos médicos diretos. O custo do PET-TC foi estimado por microcustos; os demais custos foram obtidos das tabelas de pagamento de procedimentos do SUS. Custos e benefícios foram descontados em 5%. Realizaram-se análises de sensibilidade determinística univariada e probabilística. Detectaram-se 1.875 casos de recorrência com a estratégia convencional. Uso da 18FDG-PET-TC permitiu a detecção adicional de 13 casos, com custo de R$477.633,05/caso detectado. Os parâmetros de maior impacto na análise foram: medidas de acurácia dos métodos convencionais, custo do PET-TC e taxa de desconto. Os custos da adição da PET-TC mostram-se significativos e sua introdução não é custo-efetiva.

The positron emission tomography (18FDG-PET/CT) was recently introduced in Brazilian health care for many oncology indications but accompanied by higher costs. In our study we performed a cost-effectiveness analysis of the addition of PET/CT to the conventional diagnostic work-up to detect recurrent differentiated thyroid cancers. The analytical decision model represented a hypothetical cohort of adults, thyroid cancer patients with high risk by initial stratification, submitted to total thyroidectomy and ablation with I131. The addition of PET/CT was applied to subjects with negative results on I131scintigraphy. The model was designed from the perspective of the Brazilian public health care system, with a time horizon of 10 years. Effectiveness was measured by the additional recurrent cases detected. Only direct medical costs were considered. Costs and benefits were discounted by 5%. Univariate deterministic and probabilistic sensitivity analyzes were performed to explore the uncertainties. The PET/CT diagnosed 13 additional cases compared to conventional strategy (1,888 vs 1,875) by a cost of R$477,633.05 per case detected. The parameters of greatest impact in the sensitivity analysis were the accuracy of conventional tests, cost of PET/CT and the discount rate. The costs of adding PET/CT seems significant and its introduction is not cost-effective on the Brazilian perspective.

Prevalence of exclusive lower extremity metastases at 18F-NaF PET/CT / Prevalência de metástases exclusivas em membros inferiores em exames de PET/TC com 18F-NaF

Abstract Objective: To evaluate the prevalence of exclusive lower extremity metastases, specifically in the femur and below the knee, observed at 18F-NaF PET/CT. Materials and Methods: One thousand consecutive PET/CT studies were retrospectively evaluated for the presence of exclusive uptake in lower extremities suggesting metastatic involvement. The presumptive diagnoses based on such uptakes were subsequently obtained by evaluation of other imaging studies. Results: No exclusive uptake suggestive of metastasis below the femur was observed in the present series. Exclusive uptake was observed in the proximal femur with a presumptive diagnosis of metastasis in two patients. Conclusion: The prevalence of exclusive metastasis below the femur is low and scanning from head to knees is appropriate in most cases. .

Resumo Objetivo: Avaliar a prevalência de metástases exclusivas em membros inferiores, subdivididas em lesões femorais e abaixo dos joelhos, em exames de PET/TC com 18F-NaF. Materiais e Métodos: Mil exames consecutivos foram retrospectivamente avaliados para a presença de captações exclusivas em membros inferiores sugestivas de comprometimento metastático. Os diagnósticos presuntivos dessas captações foram posteriormente obtidos pela avaliação de outros exames realizados. Resultados: Não foram observadas captações exclusivas sugestivas de metástases abaixo dos fêmures na nossa casuística. Foi observada captação exclusiva no terço superior do fêmur com diagnóstico de metástase em dois pacientes. Conclusão: A prevalência de metástase exclusiva abaixo dos fêmures é baixa e a realização do exame da cabeça até os joelhos é adequada na maioria dos casos. .

Utilidad de 11C-metionina PET/CT en neurooncología / Utility of 11C-methionine PET/CT in neuro-oncology

La tomografía por emisión de positrones con metionina carbono 11 (11C-metionina PET/TC) se utiliza en la evaluación de los tumores primarios del sistema nervioso central. Describimos nuestra experiencia sobre los primeros 4 pacientes con tumores de la serie glial estudiados con 11C-metionina PET/TC. Este es un estudio descriptivo, observacional y prospectivo. Se presentan 4 pacientes entre 38-50 años de edad con diagnóstico de gliomas (clasificación de la OMS). A todos se les realizó RM y 11C-metionina PET/TC para evaluar actividad tumoral y diferenciar progresión tumoral de pseudoprogresión. Caso 1, gliomatosis cerebri grado II posradioterapia. Caso 2, glioblastoma grado IV postratamiento RT + temozolomida. Caso 3, oligodendroglioma grado II posradioterapia en 1993. Caso 4, oligoastrocitoma anaplásico grado III postratamiento RT + temozolomida. El patrón de captación de la 11C-metionina comparativamente con la RM, demostró progresión tumoral en los casos 1, 3 y 4; en el caso 2 mostró captación aunque el diagnóstico final fue pseudoprogresión. A diferencia del PET con 18fluordeoxiglucosa, la captación de 11C-metionina en el tejido cerebral normal y en la pseudoprogresión es baja, y los gliomas se visualizan como áreas metabólicamente activas. En los casos presentados, el 11C-metionina PET/TC proveyó información valiosa sobre el comportamiento y extensión de la lesión, aunque en uno de los casos presentados no diferenció progresión tumoral de pseudoprogresión. El 11C-metionina PET/TC sería una herramienta útil en el estudio y seguimiento de los pacientes con gliomas.

Positron emission tomography (PET) with 11C-methionine (11C-methionine PET/CT) is a new technique used to evaluate primary central nervous system (CNS) tumors. We describe our experience regarding the first 4 patients with glial tumors and 11C-methionine PET/CT. This is a descriptive, observational and prospective study of 4 patients between 38-50 years of age, with different gliomas (WHO classification). MRI and 11C-methionine PET/CT were performed in all cases. Case 1, gliomatosis cerebri grade II post-radiotherapy. Case 2, oligodendroglioma grade II diagnosed and treated with radiotherapy in 1993. Case 3, glioblastoma grade IV post-radiotherapy + temozolomide. Case 4, anaplastic oligoastrocytoma grade III post-radiotherapy + temozolomide. The pattern of 11C-methionine uptake compared with MRI showed tumor progression in cases 1, 3 and 4, and in case 2 showed uptake although the final diagnosis was pseudoprogression. Unlike 18fluordeoxiglucose PET/TC, 11C-methionine uptake in normal brain tissue and pseudoprogression is low, and gliomas are displayed as metabolically active areas. The 11C-methionine PET/CT provided valuable information on the tumoral behavior and extension, although in one case presented did not differentiate tumor progression from pseudoprogression. 11C-methionine PET/CT could be a useful tool in the study and follow-up to patients with gliomas.

Melanoma metastático causando intussuscepção do intestino delgado: diagnóstico por 18F-FDG PET/TC / Metastatic melanoma causing small bowel intussusception: diagnosis by 18F-FDG PET/CT

Melanoma maligno é uma doença comum e agressiva que frequentemente causa metástase para o intestino delgado. Este estudo ilustra um caso de intussuscepção do intestino delgado causada por uma lesão metastática de melanoma visualizada à 18F-FDG PET/TC em uma paciente de 48 anos idade que realizou exame de reestadiamento.

Malignant melanoma is a common and aggressive disease that frequently causes metastases to the small bowel. This study illustrates a case of small bowel intussusception secondary to metastatic melanoma visualized at 18F-FDG PET/CT in a 48-year-old woman who had this examination for restaging purposes.

PET-TC en Endocrinología / PET-CT in Endocrinology

El examen PET-TC ha ganado un lugar en el estudio de los tumores de origen endocrino. El marcador metabólico 18F-FDG es el más empleado internacionalmente y el único por el momento en nuestro medio. Las principales limitaciones del método en Endocrinología incluyen la alta diferenciación y baja agresividad de la mayoría de los tumores endocrinos, dificultad en la identificación de lesiones de escasa celularidad y el pequeño tamaño. Las indicaciones para su empleo deben ser precisas debido a que no todos los tumores presentan sustancial avidez por este compuesto por una parte y poder extraer la máxima eficacia diagnóstica del método con adecuadas indicaciones por la otra. La indicación más importante es en pacientes con cáncer diferenciado de tiroides (CDT) con valores de Tg elevados y barridos con 131I negativos. Es aconsejable su indicación con valores de Tg mayores a los 10 ng/ml y con TSH estimulada (endógena o exógena). El objetivo es la localización de las recidivas y metástasis para su exéresis o el empleo de otras terapias alternativas al 131I. Tiene alto valor pronóstico ya que es mayor la fijación de FDG en las lesiones más agresivas. Un paciente con Tg elevada, barrido con 131I negativo y FDG positivo obliga al clínico a actuar más agresivamente para eliminar los focos patológicos, mientras que con FDG negativo puede tener una conducta expectante con controles posteriores. La introducción de otros marcadores emisores de positrones específicos como el 124I, isótopo del Iodo, seguramente aportarán mejores imágenes y diagnósticos. En los tumores neuroendocrinos la FDG tiene limitada aplicación, salvo cuando hay un grado significativo de desdiferenciación. En el cáncer medular de tiroides (CMT) es conveniente indicarlo cuando los niveles de calcitonina superan los 1000 pg/ml con el objeto de localizar el/los sitios de su producción. Con la introducción de radiofármacos más específicos de las diferentes líneas celulares que componen el espectro de los tumores neuroendocrinos con emisores de positrones, tales como 18F-DOPA, 68Ga DOTA, 11C metomidato, 11C-5-hidroxitriptofano, etc., se podrá estudiar con mayor precisión el comportamiento metabólico-molecular de estos tumores.

PET/CT scans have reached an important place in the evaluation of endocrine tumors. The metabolic marker 18F-FDG is the most widespread over the world, and, for the time being, it is the only one available in our country. The limitations of this technique in Endocrinology include high differentiation and low aggressiveness of most endocrine tumors, and low detection rate for low cellularity and/or small lesions. Indications for PET/CT scan in these tumors should be precise, due to the fact that not all of these lesions are significantly glucose-avid and to extract the maximum diagnostic efficacy of this modality to achieve the optimum diagnostic accuracy. The most important indication is DTC with high Tg levels and negative 131I scans. It is advisable to indicate a PET/CT scan in patients with Tg > 10 ng/ml and stimulated TSH (endogenous or exogenous). The aim is to locate recurrencies and metastases in order to remove them, either surgically or by any other therapy alternative to 131I. Due to higher uptake in more aggressive lesions, this study has a high prognostic value. In patients with high Tg levels, negative I-131 scan, and abnormal FDG uptake, the practitioner must act more aggressively in order to remove the pathologic foci, while with a negative FDG -PET scan, the conduct can be expectant, with periodic follow-up. The introduction of other positron-emitting tracers like 124-Iodine, is likely to yield superior quality images and provide better diagnoses. FDG has a limited efficiency in neuroendocrine tumors, unless they show a significant level of desdiffer-entiation. The scan is indicated in MTC, when calcytonin levels are above 1000 pg/ml, in order to locate the tumor sites. With the introduction of more specific positron-emitting radiopharmaceuticals, such as 18F-DOPA, 68Ga DOTA, 11C metomidate, 11C-hidroxytriptophan and others, it will be possible to study the metabolic-molecular behavior of these tumors with a more accurate approach.

PET e PET/TC em câncer de mama / PET and PET/TC in breast cancer

Nos últimos anos, a aplicação da tomografia por emissão de pósitrons (PET) com fluordesoxiglicose-18F (FDG-18F) tem melhorado significativamente a condução de pacientes com diferentes neoplasias malignas. Já se demonstrou que a associação das imagens metabólicas da PET com imagens de métodos anatômicos, como TC, pode aumentar a acurácia da PET isolada. Em nosso meio, esses equipamentos híbridos de PET/TC têm-se tornado cada vez mais disponíveis, ampliando a aplicação dessa metodologia em pacientes oncológicas. Nesta revisão, os possíveis impactos da PET e da PET/TC no manejo de pacientes com câncer de mama no diagnóstico primário, estadiamento pré-operatório, reestadiamento e na avaliação da resposta ao tratamento serão abordados. Apesar de alguns estudos terem demonstrado sua acurácia na detecção do tumor primário e no estadiamento axilar, as suas aplicações clínicas mais importantes têm sido na detecção e na definição da extensão do câncer de mama recorrente ou metastático e para a avaliação da resposta à terapia. No estadiamento, PET tem sido usada de forma complementar aos métodos convencionais de estadiamento, já que apresenta maior sensibilidade para a detecção de metástases linfonodais e osteolíticas; no entanto, não deve ser considerado um substituto para os estudos convencionais que incluem TC e cintilografia óssea.

Over the last few years, the widespread use of positron emission tomography has improved markedly the management of patients with various malignancies. It has been demonstrated, meanwhile, that the co-registration or fusion of the metabolic images obtained by PET with morphological images, such as computed tomography, improves the accuracy of stand alone PET imaging. These hybrid PET / CT equipments are becoming more and more available in Brazil, therefore increasing the use of this methodology in oncologic patients among us. In this review, we evaluate the possible impact of PET and PET / CT on the management of patients with breast cancer, with respect to primary diagnosis, preoperative staging, disease re-staging and treatment monitoring. Although studies have already proven the accuracy of PET in detecting the primary breast tumor and in axillary staging, its most important clinical applications are in re-staging, in the detection of distant metastases and in treatment monitoring. In tumor staging, PET has been used as a complementary tool to conventional imaging modalities due to its increased sensitivity in detecting nodal and lytic bone metastases; however, it should not be regarded as a substitute to conventional staging methods, including CT and bone scan.