Mimicry of Rhabdomyosarcoma by Tonsillar Actinomycosis: Case Report.

Actinomycosis is a rare infectious disease characterized by slowly progressive, chronic suppurative lesions, often mistaken for malignancies due to its ability to mimic them. It is caused by Actinomyces bacteria, which are part of the normal flora of the human oropharynx, gastrointestinal, and urogenital tracts. This case report describes a 51-year-old male with a history of mandibular rhabdomyosarcoma presenting with severe shoulder and hip pain, dysphagia, and headaches, initially suspected to be a cancer recurrence. However, after further investigation, including a PET-CT and tonsillectomy, the diagnosis of actinomycosis was confirmed through histopathological examination. The case highlights the diagnostic challenges of actinomycosis, especially in patients with complex clinical histories, emphasizing the importance of considering it as a differential diagnosis in similar presentations. The patient was treated with long-term antibiotic therapy, predominantly beta-lactams, demonstrating the necessity of a comprehensive diagnostic approach and the implications of a delayed diagnosis. This case underscores the critical need for high clinical suspicion and awareness among healthcare professionals regarding the potential for actinomycosis to mimic more common diseases, ensuring timely and accurate treatment.

Neuroinflammation and Mitochondrial Dysfunction in Parkinson's Disease: Connecting Neuroimaging with Pathophysiology.

There is a pressing need for disease-modifying therapies in patients suffering from neurodegenerative diseases, including Parkinson's disease (PD). However, these disorders face unique challenges in clinical trial designs to assess the neuroprotective properties of potential drug candidates. One of these challenges relates to the often unknown individual disease mechanisms that would, however, be relevant for targeted treatment strategies. Neuroinflammation and mitochondrial dysfunction are two proposed pathophysiological hallmarks and are considered to be highly interconnected in PD. Innovative neuroimaging methods can potentially help to gain deeper insights into one's predominant disease mechanisms, can facilitate patient stratification in clinical trials, and could potentially map treatment responses. This review aims to highlight the role of neuroinflammation and mitochondrial dysfunction in patients with PD (PwPD). We will specifically introduce different neuroimaging modalities, their respective technical hurdles and challenges, and their implementation into clinical practice. We will gather preliminary evidence for their potential use in PD research and discuss opportunities for future clinical trials.

Synthesis of a 2-nitroimidazole derivative N-(4-[18F]fluorobenzyl)-2-(2-nitro-1H-imidazol-1-yl)-acetamide ([18 F]FBNA) as PET radiotracer for imaging tumor hypoxia.

BACKGROUND: Tissue hypoxia is a pathological condition characterized by reducing oxygen supply. Hypoxia is a hallmark of tumor environment and is commonly observed in many solid tumors. Non-invasive imaging techniques like positron emission tomography (PET) are at the forefront of detecting and monitoring tissue hypoxia changes in vivo. RESULTS: We have developed a novel 18F-labeled radiotracer for hypoxia PET imaging based on cytotoxic agent benznidazole. Radiotracer N-(4-[18F]fluorobenzyl)-2-(2-nitro-1H-imidazol-1-yl)acetamide ([18F]FBNA) was synthesized through acylation chemistry with readily available 4-[18F]fluorobenzyl amine. Radiotracer [18F]FBNA was obtained in good radiochemical yields (47.4 ± 5.3%) and high radiochemical purity (> 95%). The total synthesis time was 100 min, including HPLC purification and the molar activity was greater than 40 GBq/µmol. Radiotracer [18F]FBNA was stable in saline and mouse serum for 6 h. [18F]FBNA partition coefficient (logP = 1.05) was found to be more lipophilic than [18F]EF-5 (logP = 0.75), [18F]FMISO (logP = 0.4) and [18F]FAZA (logP = - 0.4). In vitro studies showed that [18F]FBNA accumulates in gastric cancer cell lines AGS and MKN45 under hypoxic conditions. CONCLUSIONS: Hence, [18F]FBNA represents a novel and easy-to-prepare PET radioligand for imaging hypoxia.

Characterization of the serotonin 2A receptor selective PET tracer (R)-[18F]MH.MZ in the human brain.

PURPOSE: The serotonin receptor subtype 2A antagonist (5-HT2AR) (R)-[18F]MH.MZ has in preclinical studies been identified as a promising PET imaging agent for quantification of cerebral 5-HT2ARs. It displays a very similar selectivity profile as [11C]MDL 100907, one of the most selective compounds identified thus far for the 5-HT2AR. As [11C]MDL 100907, (R)-[18F]MH.MZ also displays slow brain kinetics in various animal models; however, the half-life of fluorine-18 allows for long scan times and consequently, a more precise determination of 5-HT2AR binding could still be feasible. In this study, we aimed to evaluate the potential of (R)-[18F]MH.MZ PET to image and quantify the 5-HT2AR in the human brain in vivo. METHODS: Nine healthy volunteers underwent (R)-[18F]MH.MZ PET at baseline and four out of these also received a second PET scan, after ketanserin pretreatment. Regional time-activity curves of 17 brain regions were analyzed before and after pretreatment. We also investigated radiometabolism, time-dependent stability of outcomes measures, specificity of (R)-[18F]MH.MZ 5-HT2AR binding, and performance of different kinetic modeling approaches. RESULTS: Highest uptake was determined in 5-HT2AR rich regions with a BPND of approximately 1.5 in cortex regions. No radiometabolism was observed. 1TCM and 2TCM resulted in similar outcome measure, whereas reference tissue models resulted in a small, but predictable bias. (R)-[18F]MH.MZ binding conformed to the known distribution of 5-HT2AR and could be blocked by pretreatment with ketanserin. Moreover, outcomes measures were stable after 100-110 min. CONCLUSION: (R)-[18F]MH.MZ is a suitable PET tracer to image and quantify the 5-HT2AR system in humans. In comparison with [11C]MDL 100907, faster and more precise outcome measure could be obtained using (R)-[18F]MH.MZ. We believe that (R)-[18F]MH.MZ has the potential to become the antagonist radiotracer of choice to investigate the human 5-HT2AR system.

Coronary microvascular dysfunction in women with nonobstructive ischemic heart disease as assessed by positron emission tomography.

Traditional approaches for risk assessment of ischemic heart disease (IHD) are based on the physiological consequences of an epicardial coronary stenosis. Of note, normal coronary arteries or nonobstructive coronary artery disease (CAD) is a common finding in women with signs and symptoms of ischemia. Therefore, assessment of risk based on a coronary stenosis approach may fail in women. Positron emission tomography (PET) quantifies absolute myocardial blood flow (MBF) which may help to elucidate other mechanisms involved such as endothelial dysfunction and alterations in the smooth muscle cell relaxation responsible for IHD in women. The objective of the present review is to describe the current state of the art of PET imaging in assessing IHD in women with nonobstructive CAD.

Imaging for pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide due to its aggressiveness and the challenge to early diagnosis. Complete surgical resection is the only curative option, but fewer than 20% of patients have potentially resectable disease at the time of the diagnosis. Radiologists can assess whether PDAC is resectable, borderline resectable, locally advanced or metastatic based on current imaging tests. This review will outline the role of imaging in both the diagnosis and staging of PDAC, with the goal of assisting the multidisciplinary team in tailoring the best treatment for patients.

A novel non-Hodgkin lymphoma murine model closer to the standard clinical scenario.

BACKGROUND: Non-Hodgkin lymphomas (NHL) are the most frequent hemato-oncological malignancies. Despite recent major advances in treatment, a substantial proportion of patients relapses highlighting the need for new therapeutic modalities. Promissory results obtained in pre-clinical studies are usually not translated when moving into clinical trials. Pre-clinical studies are mainly conducted in animals with high tumor burden; instead patients undergo chemotherapy as first line of treatment and most likely are under remission when immunotherapies are applied. Thus, an animal model that more closely resembles patients' conditions would be a valuable tool. METHODS: BALB/c mice were injected subcutaneously with A20 lymphoma cells and after tumor development different doses of chemotherapy were assessed to find optimal conditions for minimal residual disease (MRD) establishment. Tumor growth and survival, as well as drugs side effects, were all evaluated. Complete lymphoma remission was monitored in vivo using positron emission tomography (PET), and the results were correlated with histology. Immunological status was assessed by splenocytes proliferation assays in NHL-complete remission mice and by analyzing tumor cell infiltrates and chemokines/cytokines gene expression in the tumor microenvironment of animals with residual lymphoma. RESULTS: Two cycles of CHOP chemotherapy at days 25 and 35 post-tumor implantation induced complete remission for around 20 days. PET showed to be a suitable follow-up technique for MRD condition with 85.7 and 75% of sensibility and specificity respectively. Proliferative responses upon mitogen stimulation were similar in animals that received chemotherapy and wild type mice. Tumors from animals with residual lymphoma showed higher numbers of CD4+ and CD8+ and similar numbers of NK, neutrophils and Tregs infiltrating cells as compared with non-treated animals. Gene expression of several cytokines as well as an array of chemokines associated with migration of activated T cells to tumor sites was upregulated in the tumor microenvironment of animals that received chemotherapy treatment. CONCLUSIONS: We established a NHL-B pre-clinical model using standard chemotherapy to achieve MRD in immunocompetent animals. The MRD condition is maintained for approximately 20 days providing a therapeutic window of time where new immunotherapies can be tested in conditions closer to the clinics.

Impact of Single-Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) and Positron Emission Tomography/Computed Tomography (PET/CT) in the Diagnosis of Traumatic Brain Injury (TBI): Case Report.

Traumatic brain injury (TBI) is defined as damage to the brain resulting from an external force. TBI, a global leading cause of death and disability, is associated with serious social, economic, and health problems. In cases of mild-to-moderate brain damage, conventional anatomical imaging modalities may or may not detect the cascade of metabolic changes that have occurred or are occurring at the intracellular level. Functional nuclear medicine imaging and neurophysiological parameters can be used to characterize brain damage, as the former provides direct visualization of brain function, even in the absence of overt behavioral manifestations or anatomical findings. We report the case of a 30-year-old Hispanic male veteran who, after 2 traumatic brain injury events, developed cognitive and neuropsychological problems with no clear etiology in the presence of negative computed tomography (CT) findings.

Accuracy of positron emission tomography and positron emission tomography-CT in the detection of differentiated thyroid cancer recurrence with negative (131) I whole-body scan results: A meta-analysis.

BACKGROUND: The purpose of this review was to present a meta-analysis aimed to evaluate the accuracy of positron emission tomography (PET) and PET-CT for detecting recurrence of differentiated thyroid carcinoma (DTC) not identified by (131) I whole-body scintigraphy. METHODS: MEDLINE, EMBASE, LILACS, and Cochrane databases were searched for studies published between January 1985 and March 2012. Systematic methods were used to select and evaluate the quality of studies. Pooled sensitivity and specificity for conventional PET and PET-CT was estimated using random effects model. RESULTS: Twenty studies were included in the systematic review; the data of 18 studies were used in the meta-analysis. The combined sensitivity and specificity for conventional PET were both found to be 84%; for PET-CT, they were 93% and 81%, respectively. The overall accuracies were 91% and 93%, respectively. CONCLUSION: (18) Fluorodeoxyglucose (FDG)-PET and PET-CT are highly accurate diagnostics tools for DTC recurrence in patients who present a negative whole-body scintigraphy and could impact the clinical and therapeutic management of DTC.

Myocardial blood flow assessment with 82rubidium-PET imaging in patients with left bundle branch block

OBJECTIVES: Perfusion abnormalities are frequently seen in Single Photon Emission Computed Tomography (SPECT) when a left bundle branch block is present. A few studies have shown decreased coronary flow reserve in the left anterior descending territory, regardless of the presence of coronary artery disease. OBJECTIVE: We sought to investigate rubidium-82 (82Rb) positron emission tomography imaging in the assessment of myocardial blood flow and coronary flow reserve in patients with left bundle branch block. METHODS: Thirty-eight patients with left bundle branch block (GI), median age 63.5 years, 22 (58%) female, 12 with coronary artery disease (≥70%; GI-A) and 26 with no evidence of significant coronary artery disease (GI-B), underwent rest-dipyridamole stress 82Rb-positron emission tomography with absolute quantitative flow measurements using Cedars-Sinai software (mL/min/g). The relative myocardial perfusion and left ventricular ejection fraction were assessed in 17 segments. These parameters were compared with those obtained from 30 patients with normal 82Rb-positron emission tomography studies and without left bundle branch block (GII). RESULTS: Stress myocardial blood flow and coronary flow reserve were significantly lower in GI than in GII (p<0.05). The comparison of coronary flow reserve between GI-A and GI-B showed that it was different from the global coronary flow reserve (p<0.05) and the stress flow was significantly lower in the anterior than in the septal wall for both groups. Perfusion abnormalities were more prevalent in GI-A (p=0.06) and the left ventricular ejection fraction was not different between GI-A and GI-B, whereas it was lower in GI than in GII (p<0.001). CONCLUSION: The data confirm that patients with left bundle branch block had decreased myocardial blood flow and coronary flow reserve and coronary flow reserve assessed by 82Rb-positron emission tomography imaging may be useful in identifying coronary artery disease in patients with left bundle branch block.

[Positron emission tomography with (18)F-FDG in the evaluation of patients with rheumatoid arthritis--a systematic review]. / Tomografia por emissão de pósitrons com FDG-(18)F na avaliação de pacientes com artrite reumatoide--revisão sistemática.

INTRODUCTION: Rheumatoid arthritis (RA) is a disease characterized by inflammation of the synovial membrane. Several authors have investigated the role of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose ((18)F-FDG) in RA. OBJECTIVES: To systematically review the current literature on the role of (18)F-FDG PET in the diagnosis, determination of disease activity and assessment of treatment response in patients with RA. METHODS: Searches were conducted in Medline, Cochrane Library, Lilacs, Pubmed and Scopus in Portuguese, English and Spanish languages, using the keywords "rheumatoid arthritis", "synovitis", "FDG", "PET", "glycolytic metabolism" and "disease activity". RESULTS: 142o articles were initially identified, of which only 40 were related directly to the subject. Twelve original articles and three case reports that met the inclusion criteria were selected. DISCUSSION: The presence of activated macrophages and fibroblasts in pannus are responsible for the intense periarticular uptake of (18)F-FDG. The uptake patterns do not allow the differential diagnosis with other arthritides. The uptake intensity and the number of joints involved are metabolic parameters of disease activity that correlate well with the composite indices. Longitudinal studies of PET have proven useful in assessing the response to treatment with anti-TNF. When performed early, PET can predict the therapeutic response. CONCLUSION: Although the actual role of this new technique for the investigation of RA is not yet established, (18)F-FDG PET is a promising tool in determining the activity and prediction of response to treatment of patients with RA.

Tomografia por emissão de pósitrons com FDG-18F na avaliação de pacientes com artrite reumatoide - revisão sistemática / Positron emission tomography with 18F-FDG in the evaluation of patients with rheumatoid arthritis - a systematic review

Introdução A artrite reumatoide (AR) é uma doença caracterizada pela inflamação da membrana sinovial. Diversos autores têm investigado o papel da tomografia por emissão de pósitrons (PET) com flúor-18 (FDG-18F) na AR. Objetivos Revisão sistemática da literatura atual sobre o papel do PET com FDG-18F no diagnóstico, determinação da atividade da doença e avaliação da resposta ao tratamento em pacientes com AR. Métodos Foram realizadas buscas nas bases de dados Medline, Biblioteca Cochrane, Lilacs, Pubmed e Scopus nos idiomas português, inglês e espanhol, utilizando as palavras-chave «artrite reumatoide¼, «sinovite¼, «FDG¼, «PET¼, «metabolismo glicolítico¼ e «atividade da doença¼. Resultados 142 artigos foram inicialmente identificados, dos quais apenas 40 relacionavam-se diretamente ao tema. Foram selecionados 12 artigos originais e três relatos de caso que preenchiam os critérios de inclusão. Discussão A presença de fibroblastos e macrófagos ativados no pannus é responsável pela intensa captação periarticular de FDG-18F. Os padrões de captação não permitem o diagnóstico diferencial com outras artrites. A intensidade de captação e o número de articulações envolvidas são parâmetros metabólicos de atividade da doença que apresentam boa correlação com os índices compostos. Estudos longitudinais de PET têm se mostrado úteis na avaliação da resposta ao tratamento com anti-TNF. Quando realizado precocemente, PET pode predizer a resposta terapêutica. Conclusão Embora o real papel dessa nova técnica na investigação da AR ainda não esteja estabelecido, PET com FDG-18F é uma ferramenta ...

Introduction Rheumatoid arthritis (RA) is a disease characterized by inflammation of the synovial membrane. Several authors have investigated the role of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (18F-FDG) in RA. Objectives To systematically review the current literature on the role of 18F-FDG PET in the diagnosis, determination of disease activity and assessment of treatment response in patients with RA. Methods Searches were conducted in Medline, Cochrane Library, Lilacs, Pubmed and Scopus in Portuguese, English and Spanish languages, using the keywords «rheumatoid arthritis¼, «synovitis¼, «FDG¼, «PET¼, «glycolytic metabolism¼ and «disease activity¼. Results One hundred and forty-two articles were initially identified, of which only 40 were related directly to the subject. Twelve original articles and three case reports that met the inclusion criteria were selected. Discussion The presence of activated macrophages and fibroblasts in pannus are responsible for the intense periarticular uptake of 18F-FDG. The uptake patterns do not allow the differential diagnosis with other arthritides. The uptake intensity and the number of joints involved are metabolic parameters of disease activity that correlate well with the composite indices. Longitudinal studies of PET have proven useful in assessing the response to treatment with anti-TNF. When performed early, PET can predict the therapeutic response. Conclusion Although the actual role of this new technique for the investigation of RA is not yet established, 18F-FDG PET is a promising tool in determining the activity and prediction of response to treatment of patients with RA. .

Processamento de estruturas tridimensionais de Medicina Nuclear na modalidade PET / Processing of three-dimensional structures of Nuclear Medicine in PET modality

A Medicina Nuclear, como especialidade de obtenção de imagens médicas é um dos principais procedimentos utilizados hoje nos centros de saúde, tendo como grande vantagem a capacidade de analisar o comportamento metabólico do paciente. Este projeto está baseado em imagens médicas obtidas através da modalidade PET (Positron Emission Tomography). Para isso, foi desenvolvida uma estrutura de processamento de imagens tridimensionais PET, constituída por etapas sucessivas que se iniciam com a obtenção das imagens padrões (gold standard), sendo utilizados para este fim volumes simulados do Ventrículo Esquerdo do Coração criadas como parte do projeto, assim como phantoms gerados com o software NCAT-4D. A seguir, nos volumes simulados é introduzido ruído Poisson que é o ruído característico das imagens PET. Na sequência é executada uma etapa de pré-processamento, utilizando alguns filtros 3D tais como o filtro da mediana, o filtro da Gaussiana ponderada e o filtro Anscombe/Wiener. Posteriormente é aplicada a etapa de segmentação, processo baseado na teoria de Conectividade Fuzzy sendo implementadas quatro diferentes abordagens 3D: Algoritmo Genérico, LIFO, kTetaFOEMS e Pesos Dinâmicos. Finalmente, um procedimento de avaliação conformado por três parâmetros (Verdadeiro Positivo, Falso Positivo e Máxima Distância) foi utilizado para mensurar o nível de eficiência e precisão do processo. Constatou-se que o par Filtro - Segmentador constituído pelo filtro Anscombe/Wiener junto com o segmentador Fuzzy baseado em Pesos Dinâmicos proporcionou os melhores resultados, com taxas de VP e FP na ordem de 98,49 ± 0,27% e 2,19 ± 0,19%, respectivamente, para o caso do volume do Ventrículo Esquerdo simulado. Com o conjunto de escolhas feitas ao longo da estrutura de processamento, encerrou-se o projeto analisando um número reduzido de volumes pertencentes a um exame PET real, obtendo-se a quantificação dos volumes.

The Nuclear medicine, as a specialty to obtain medical images is very important, and it has became one of the main procedures utilized in Health Care Centers to analyze the metabolic behavior of the patient. This project was based on medical images obtained by the PET modality (Positron Emission Tomography). Thus, we developed a framework for processing Nuclear Medicine three-dimensional images of the PET modality, which is composed of consecutive steps that start with the generation of standard images (gold standard) by using simulated images of the Left Ventricular Heart, such as phantoms obtained from the NCAT-4D software. Then, Poisson quantum noise was introduced into the whole volume to simulate the characteristic noises in PET images. Subsequently, the pre-processing step was executed by using specific 3D filters, such as the median filter, the weighted Gaussian filter, and the Anscombe/Wiener filter. Then the segmentation process, which is based on the Fuzzy Connectedness theory, was implemented. For that purpose four different 3D approaches were implemented: Generic, LIFO, kTetaFOEMS, and Dynamic Weight algorithm. Finally, an assessment procedure was used as a measurement tool to quantify three parameters (True Positive, False Positive and Maximum Distance) that determined the level of efficiency and precision of our process. It was found that the pair filter - segmenter formed by the Anscombe/Wiener filter together with the Fuzzy segmenter based on Dynamic Weights provided the best results, with VP and FP rates of 98.49 ± 0.27% and 2.19 ± 0.19%, respectively, for the simulation of the Left Ventricular volume. Along with the set of choices made during the processing structure, the project was finished with the analysis of a small number of volumes that belonged to a real PET test, thus the quantification of the volumes was obtained.

Adequação de modelo compartimental para exames de tomografia por emissão de pósitrons / Adequacy of compartmental model for positron emission tomography examinations

O presente trabalho objetiva a seleção do modelo compartimental mais adequado ao estudo da dinâmica fisiológica em exames de tomografia por emissão de pósitrons (PET). Para tanto, propõe-se utilizar o critério de informação de Akaike para a seleção do modelo, e a metodologia de equações de sensibilidade e o algoritmo de Levenberg-Marquardt para a tarefa de estimação de parâmetros característicos e, consequentemente, do erro residual da estimativa. São consideradas três estruturas compartimentais compostas, respectivamente, por dois compartimentos e duas constantes características, três compartimentos e quatro constantes características e quatro compartimentos e seis constantes características. Os dados considerados neste trabalho foram sintetizados preocupando-se em reunir as principais características de um exame de tomografia real, tais como tipo e nível de ruído e morfologia de função de excitação do sistema. Aplicando-se a metodologia proposta em três níveis de ruído (baixo, médio e alto), obteve-se concordância do melhor modelo em graus forte e considerável (com índices de Kappa iguais a 0,95, 0,93 e 0,63, respectivamente). Observou-se que, com elevado nível de ruído e modelos mais complexos (quatro compartimentos), a classificação se deteriora devido ao pequeno número de dados para a decisão. Foram desenvolvidos programas e uma interface gráfica que podem ser utilizados na investigação, elaboração, simulação, estimativa de parâmetros e identificação do modelo compartimental para apoio e análise de diagnósticos clínicos e práticas científicas.

The objective of this work is the determination of the most adequate compartmental model for the study of physiological dynamics based on positron emission tomography (PET) exams. We propose the use of Akaike’s information criterion for the optimal model selection, and Levenberg-Marquardt algorithm with sensitivity equations for the task of estimating the characteristic parameters of the differential equations describing the models. We have considered three compartmental structures represented, respectively, by two compartments and two characteristic constants, three compartments and four characteristic constants and four compartments and six characteristics constants. The data considered in this work were synthesized taking into account key features of a real tomography exam, such as type and level of noise and morphology of the input function of the system. Applying the proposed methodology with three noise levels (low, medium and high), we obtained agreement of the best model with strong and considerable degrees (with Kappa indexes equal to  0.95, 0.93 and  0.63, respectively). It was observed that, with high noise level and more complex models (four compartments), the classification is deteriorated due to lack of data for the decision. Programs have been developed and a graphical interface that can be used in research, development, simulation and parameter identification of compartmental models, supporting analysis of clinical diagnostics and scientific practices.

PET imaging in differentiated thyroid cancer: where does it fit and how do we use it?

Positron emission tomography (PET) is a rapidly evolving imaging modality that has gained widespread acceptance in oncology, with several radionuclides applicable to thyroid cancer. Thyroid cancer patients have been studied most commonly using 18F-Fluorodeoxyglucose (FDG)-PET, with perhaps the greatest utility being the potential localization of tumor in differentiated thyroid cancer (DTC) patients who are radioiodine whole body scan (WBS) negative and thyroglobulin (Tg) positive. Also of value is the identification of patients unlikely to benefit from additional 131I therapy and identification of patients at highest risk of disease-specific mortality, which may prompt more aggressive therapy or enrollment in clinical trials. Emerging data suggest that PET/CT fusion studies provide increased accuracy and modify the treatment plan in a significant number of DTC cases when compared to PET images alone. However, studies documenting improvements in survival and tumor recurrence attributable to FDG-PET imaging in thyroid cancer patients are lacking. Specific case examples of thyroid cancer patients who appear to have benefited from FDG-PET imaging do exist, while less data are available in the setting of anaplastic or medullary thyroid carcinoma. This article reviews the utility and limitations of FDG-PET in DTC management, and offers practical recommendations.

Positron emission tomography (PET) é uma modalidade de imagem que vem evoluindo rapidamente e tem ganho ampla aceitação na oncologia em geral e no câncer da tiróide em particular, graças a uma série de radionuclídeos. Pacientes com doenças da tiróide têm sido estudados principalmente com 18F-Fluorodeoxiglicose (FDG)-PET, cuja maior utilidade talvez seja a de poder localizar tumor em pacientes negativos na pesquisa de corpo inteiro e com tireoglobulina positiva. Também é útil na identificação de pacientes que não devem se beneficiar de terapia adicional com 131I e de pacientes de alto risco que podem se beneficiar de terapias mais agressivas ou testes clínicos com drogas alvo-dirigidas. Dados recentes sugerem que a fusão PET/CT aumenta a acurácia e modifica o plano terapêutico de um número significativo de casos de CDT comparada com as imagens de PET apenas. Entretanto, ainda não existem estudos que documentem melhora na sobrevida e na recorrência decorrentes da imagem por FDG-PET em pacientes com câncer da tiróide. Existem exemplos específicos de casos de CDT que aparentemente se beneficiaram do FDG-PET, mas há menos dados relativos ao carcinoma anaplásico ou ao medular. Este artigo revê a utilidade e as limitações do FDG-PET no tratamento do CDT e oferece recomendações práticas.

Evaluación de nódulos y masas pulmonares con PET FDG de alta resolución / 18-Fluorodeoxyglucose positron emission tomography in patients with pulmonary nodules

Introducción: El diagnóstico y etapificación de pacientes portadores de lesiones pulmonares con PET-FDG permite optimizar el manejo y seleccionar la terapia más adecuada para cada uno. Objetivo: Analizar nuestra experiencia preliminar con PET-FDG en la caracterización metabólica de nódulos o masas pulmonares, correlacionándolo con histología cuando estaba disponible y evaluando el impacto en la conducta terapéutica. Material y Método: Se analizaron 58 pacientes referidos para evaluación de nódulo o masa pulmonar (62±7 años de edad; 48% sexo masculino; 40% fumadores). Los PET se realizaron en ayunas, utilizando 13 mCi de FDG-F18, con glicemia preinyección de 101± 5 mg/dl. Se adquirieron imágenes de cuerpo entero con análisis visual de cortes coronales, sagitales y transaxiales e imágenes 3D, así como análisis cuantitativo del índice de captación estandarizada SUV. Los estudios se compararon con histología y seguimiento clínico. Resultados: En 22 pacientes (38%), las lesiones pulmonares fueron hipermetabólicas y en 64%, no hubo evidencias de actividad tumoral. En 24% de los pacientes, se encontraron además lesiones extrapulmonares no sospechadas por otras técnicas de imágenes. El rango de tamaño de los nódulos/masas pulmonares era de 0,5 a 7 cm; en el grupo de PET positivo, el tamaño era mayor a 0,8 cm. Se obtuvo histología en 16/58: en 12 de ellos, se confirmó la presencia de neoplasia (75%), correspondiendo la mayoría a adenocarcinoma. Dos pacientes fueron falsos positivos, demostrándose en uno, un schwanoma abscedado y en el otro, un hamartoma. En 2 pacientes con nódulos sin actividad hipermetabólica al PET (estudio normal), sometidos a cirugía por las características del nódulo al TC, se corroboraron lesiones benignas. En los restantes pacientes con lesiones negativas, el seguimiento clínico no ha demostrado eventos hasta la fecha. Un paciente referido por nódulo pulmonar no fue incluido en el análisis debido a que en el PET presentaba ...

Background: The diagnosis and staging of pulmonary lesions with positron emission tomography (PET) with 18fluorodeoxyglucose (FDG) helps in the selection of the optimal therapy. Aim: To analyze the usefulness of FDG PET in the characterization of pulmonary nodules. Patients and Methods: Fifty eight patients referred for the assessment of a pulmonary nodule or mass (aged 62 ± 7 years, 28 males, 40% smokers), were studied. The imaging study was perfomed in the fasting state injecting 13 mCi of 18FDG. Pre injection blood glucose was 101 ± 5 mg/dl. Whole body images were acquired with visual analysis of coronal, sagittal and trans axial slices and three dimensional images. The standardized uptake value (SUV) was also calculated. Results: Pulmonary lesions were hypermetabolic in 22 patients (38%) and in the rest, there was no evidence of tumor activity. Extrapulmonary lesions were detected in 24% of patients. The size of the nodules ranged from 0.5 to 7 cm. in diameter. Those with positive PET had lesions over 0.8 cm diameter. In 12 of 16 patients with pathological study, the presence of cancer was confirmed. Two patients had false positive images. One had an abscessed Schwanoma and the other, a hamartoma. Two patients with PET images not suspicious of tumor, were operated and the pathology confirmed the absence of cancer. In the rest of patients with a negative study, the clinical follow up has been uneventful. In one patient with multiple hypermetabolic lesions with a pattern suggestive of sarcoidosis, the diagnosis was pathologically confirmed. Conclusions: FDG PET is useful for the characterization of pulmonary lesions and nodules.