A Importância de estudos dinâmicos em PET/CT para avaliação de doenças oncológicas

A Medicina Nuclear (MN) permite investigar o estado fisiológico dos tecidos de forma minimamente invasiva, usando radiofármacos (rf’s), moléculas compostas por um análogo biológico específico desses processos fisiológicos e um marcador radioativo (radionuclídeo). PET/CT (do acrónimo inglês Positron Emission Tomography/Computed Tomography), uma das modalidades de imagem em MN, está a expandir-se rapidamente em muitos Países. As imagens obtidas revelam a biodistribuição dos rf’s usados e permitem conhecer a sua distribuição precisa no organismo. 18F-Fluorodesoxiglicose (FDG), um análogo da glicose, é o rf mais comumente utilizado, isto porque em neoplasias as células são geralmente caracterizadas pelo aumento do metabolismo da glicose. A quantificação realizada em imagens de PET, tem por base uma estimativa quantitativa do metabolismo da glicose no tumor, utilizando o índice de captação estandardizado, SUV (do acrónimo inglês Standard Uptake Value). A realização de estudos dinâmicos em PET/CT, isto é, realizados em sequência temporal imediatamente após a administração endovenosa do rf e, durante um período de tempo pré-determinado (por exemplo, 15 minutos) permite que o registo da cinética inicial dos rf’s seja estudado. A análise dos dados obtidos com o estudo dinâmico permite compreender o grau e a perfusão tumoral. Habitualmente, quanto maior a captação de 18F-FDG num tumor, maior é a sua atividade metabólica glicolítica, o que tem sido traduzido em maior agressividade tumoral. Nesta investigação, realizaram-se estudos dinâmicos num grupo restrito de patologias oncológicas, nomeadamente: carcinoma da bexiga, carcinoma do colo do útero, carcinoma colorretal, carcinoma do endométrio, metástases hepáticas e adenocarcinoma pancreático. Realizaram-se estudos dinâmicos durante cerca de 10/15 minutos, com 1minuto por frame. O objetivo desta Investigação é tentar compreender se, tumores com maior perfusão respondem melhor à Radioterapia (RT), ou se, a resposta é independente da perfusão. Para avaliar os valores de SUV’s ao longo tempo, realizaram-se ROI’s (do acrónimo inglês Region of Interest), nas artérias femorais ou aorta e na lesão tumoral. Com estes dados, criaram-se gráficos de atividade/tempo onde, no eixo das abcissas é representado o tempo e no eixo das ordenadas os valores de SUV. A partir destes gráficos e dos dados neles contidos, calculou-se o Índice de Perfusão Tumoral através de 2 métodos: A, Método Trapezoidal de Aproximação que relaciona a razão entre a área perfusional do tumor e a área de fluxo arterial, até ao momento do cruzamento das curvas; B, mais simples, calculando o Índice de Perfusão do Tumor através da razão entre o valor de SUV máximo da curva tumoral e da curva arterial até ao momento do cruzamento das curvas. O Método de Comparação de Métodos de Altman&Bland, revelou que tanto o método A como o método B são semelhantes para o cálculo do Índice de Perfusão Tumoral. Em conclusão, apesar do número reduzido de indivíduos estudados, os dados apresentados indicam que existe uma tendência para que haja melhor resposta à RT por parte dos tumores com maior índice metabólico e maior índice de perfusão. Os tumores com menor índice metabólico e menor grau perfusional parece que respondem pior à RT.

18FDG uptake during induction chemoradiation for oesophageal cancer fails to predict histomorphological tumour response

To determine whether [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) could predict the pathological response in oesophageal cancer after only the first week of neoadjuvant chemoradiation. Thirty-two patients with localised oesophageal cancer had a pretreatment PET scan and a repeat after the first week of chemoradiation. The change in mean maximum standardised uptake value (SUV) and volume of metabolically active tissue (MTV) was compared with the tumour regression grade (TRG) in the final histology. Those who achieved a TRG of 1 and 2 were deemed responders and 3-5 nonresponders. In the responders (28%), the SUV fell from 12.6 (±6.3) to 8.1 (±2.9) after 1 week of chemoradiation (P = 0.070). In nonresponders (72%), the results were 9.7 (±5.4) and 7.1 (±3.8), respectively (P = 0.003). The MTV in responders fell from 36.6 (±22.7) to 22.3 (±10.4) cm3 (P = 0.180), while in nonresponders, this fell from 35.9 (±36.7) to 31.9 (±52.7) cm3 (P = 0.405). There were no significant differences between responders and nonresponders. The hypothesis that early repeat FDG-PET scanning may predict histomorphologic response was not proven. This may reflect an inflammatory effect of radiation that obscures tumour-specific metabolic changes at this time. This assessment may have limited application in predicting response to multimodal regimens for oesophageal cancer. © 2006 Cancer Research UK.

Epigenetic regulation of glucose transporters in non-small cell lung cancer

Due to their inherently hypoxic environment, cancer cells often resort to glycolysis, or the anaerobic breakdown of glucose to form ATP to provide for their energy needs, known as the Warburg effect. At the same time, overexpression of the insulin receptor in non-small cell lung cancer (NSCLC) is associated with an increased risk of metastasis and decreased survival. The uptake of glucose into cells is carried out via glucose transporters or GLUTs. Of these, GLUT-4 is essential for insulin-stimulated glucose uptake. Following treatment with the epigenetic targeting agents histone deacetylase inhibitors (HDACi), GLUT-3 and GLUT-4 expression were found to be induced in NSCLC cell lines, with minimal responses in transformed normal human bronchial epithelial cells (HBECs). Similar results for GLUT-4 were observed in cells derived from liver, muscle, kidney and pre-adipocytes. Bioinformatic analysis of the promoter for GLUT-4 indicates that it may also be regulated by several chromatin binding factors or complexes including CTCF, SP1 and SMYD3. Chromatin immunoprecipitation studies demonstrate that the promoter for GLUT-4 is dynamically remodeled in response to HDACi. Overall, these results may have value within the clinical setting as (a) it may be possible to use this to enhance fluorodeoxyglucose (18F) positron emission tomography (FDG-PET) imaging sensitivity; (b) it may be possible to target NSCLC through the use of HDACi and insulin mediated uptake of the metabolic targeting drugs such as 2-deoxyglucose (2-DG); or (c) enhance or sensitize NSCLC to chemotherapy. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

Anterior temporal cortex and semantic memory : reconciling findings from neuropsychology and functional imaging

Studies of semantic impairment arising from brain disease suggest that the anterior temporal lobes are critical for semantic abilities in humans; yet activation of these regions is rarely reported in functional imaging studies of healthy controls performing semantic tasks. Here, we combined neuropsychological and PET functional imaging data to show that when healthy subjects identify concepts at a specific level, the regions activated correspond to the site of maximal atrophy in patients with relatively pure semantic impairment. The stimuli were color photographs of common animals or vehicles, and the task was category verification at specific (e.g., robin), intermediate (e.g., bird), or general (e.g., animal) levels. Specific, relative to general, categorization activated the antero-lateral temporal cortices bilaterally, despite matching of these experimental conditions for difficulty. Critically, in patients with atrophy in precisely these areas, the most pronounced deficit was in the retrieval of specific semantic information.

Synthesis of a multimodal molecular imaging probe based on a hyperbranched polymer architecture

Molecular imaging is utilised in modern medicine to aid in the diagnosis and treatment of disease by allowing its spatiotemporal state to be examined in vivo. This study focuses on the development of novel multimodal molecular imaging agents based on hyperbranched polymers that combine the complementary capabilities of optical fluorescence imaging and positron emission tomography-computed tomography (PET/CT) into one construct. RAFT-mediated polymerisation was used to prepare two hydrophilic hyperbranched polymers that were differentiated by their size and level of branching. The multiple functional end-groups facilitated covalent attachment of both near infrared fluorescent dyes for optical imaging, as well as a copper chelator allowing binding of 64Cu as a PET radio nuclei. In vivo multimodal imaging of mice using PET/CT and planar optical imaging was first used to assess the biodistribution of the polymeric materials and it was shown that the larger and more branched polymer had a significantly longer circulation time. The larger constructs were also shown to exhibit enhanced accumulation in solid tumours in a murine B16 melanoma model. Importantly, it was demonstrated that the PET modality gave rise to high sensitivity immediately after injection of the agent, while the optical modality facilitated extended longitudinal studies, thus highlighting how the complementary capabilities of the molecular imaging agents can be useful for studying various diseases, including cancer.

Stem cell transplantation in brain tumors: a new field for molecular imaging?

Neural stem cells have been proposed as a new and promising treatment modality in various pathologies of the central nervous system, including malignant brain tumors. However, the underlying mechanism by which neural stem cells target tumor areas remains elusive. Monitoring of these cells is currently done by use of various modes of molecular imaging, such as optical imaging, magnetic resonance imaging and positron emission tomography, which is a novel technology for visualizing metabolism and signal transduction to gene expression. In this new context, the microenvironment of (malignant) brain tumors and the blood-brain barrier gains increased interest. The authors of this review give a unique overview of the current molecular-imaging techniques used in different therapeutic experimental brain tumor models in relation to neural stem cells. Such methods for molecular imaging of gene-engineered neural stem/progenitor cells are currently used to trace the location and temporal level of expression of therapeutic and endogenous genes in malignant brain tumors, closing the gap between in vitro and in vivo integrative biology of disease in neural stem cell transplantation.

Diagnosis and workup of 522 consecutive patients with neuroendocrine neoplasms in Switzerland.

BACKGROUND: Neuroendocrine neoplasms (NENs) are difficult to diagnose. We used SwissNET data to characterise NEN patients followed in the two academic centres of western Switzerland (WS), and to compare them with patients followed in eastern Switzerland (ES) as well as with international guidelines. METHOD: SwissNET is a prospective database covering data from 522 consecutive patients (285 men, 237 women) from WS (n = 99) and ES (n = 423). RESULTS: Mean ± SD age at diagnosis was 59.0 ± 15.7 years. Overall, 76/522 experienced a functional syndrome, with a median interval of 1.0 (IQR: 1.0-3.0) year between symptoms onset and diagnosis. A total of 51/522 of these tumours were incidental. The primary tumour site was the small intestine (29%), pancreas (21%), appendix (18%) and lung (11%) in both regions combined. In all, 513 functional imaging studies were obtained (139 in WS, 374 in ES). Of these, 381 were 111In-pentetreotide scintigraphies and 20 were 68Ga-DOTATOC PET. First line therapy was surgery in 87% of patients, medical therapy (biotherapy or chemotherapy) in 9% and irradiation in 3% for both regions together. CONCLUSION: Swiss NEN patients appear similar to what has been described in the literature. Imaging by somatostatin receptor scintigraphy (SRS) is widely used in both regions of Switzerland. In good accordance with published guidelines, data on first line therapy demonstrate the crucial role of surgery. The low incidence of biotherapy suggests that long-acting somatostatin analogues are not yet widely used for their anti-proliferative effects. The SwissNET initiative should help improve compliance with ENETS guidelines in the workup and care of NEN patients.

Évaluation pré-clinique du (–)-[18F]FEOBV: Profil métabolique plasmatique.

Introduction. Plusieurs maladies neurodégénératives bénéficieraient de meilleures ap-proches diagnostiques, dont la maladie d’Alzheimer. Celle-ci affecte en particulier les systèmes cholinergiques du SNC, et de nombreuses études d’imagerie ont tenté d’évaluer la dégénérescence de ce système à des fins diagnostiques, à l’aide de ligands radioactifs de diverses composantes du système ACh. En définitive, la plupart de ces études ne se sont pas montrées satisfaisantes. À la recherche de meilleures approches dans ce domaine, nous avons décidé d’évaluer les possibilités offertes par le (-)-[18F]Fluoroethoxy-benzovesamicol ((-)-[18F]FEOBV), un agent émetteur de positons se liant au VAChT de façon spécifique et réversible. Avant d’en arriver à une utilisation humaine cependant, une validation animale en plusieurs étapes s’avère nécessaire, mais celle-ci nous est apparue justifiée à la lumière de résultats d’études préliminaires en TEP chez le rat, qui se sont montrées très prometteuses. Nous nous sommes donc attaqués à la caractérisation du métabolisme de cet agent. Ceci a exigé, dans un premier temps, la mise au point d’une méthode chromatographique d’analyse des métabolites sanguins et, dans un deuxième temps, l’évaluation de ces métabolites et de leur cinétique chez le rat. Ces données permettront ultérieurement, chez l’humain, de procéder à des études quantitatives en TEP. Étude #1: Une fois les paramètres chromatographiques optimisés, le TR du (–)-FEOBV fut établi à 7.92 ± 0.18 minutes. Étude #2 : Le métabolisme in vivo s’est montré très rapide et temporellement variable, mais un seul métabolite hydrophile a été identifié. La fonction d’apport au cerveau du (–)-[18F]FEOBV a pu être établie après correction pour la présence du métabolite détecté. Conclusion. Dans l’ensemble, le (–)-[18F]FEOBV semble très prometteur en tant que marqueur biologique du système cholinergique pré-synaptique.

SPECT (Single photon emission tomography): Gama câmara, reconstrução tomográfica e características funcional

The SPECT (Single Photon Emission Computed Tomography) systems are part of a medical image acquisition technology which has been outstanding, because the resultant images are functional images complementary to those that give anatomic information, such as X-Ray CT, presenting a high diagnostic value. These equipments acquire, in a non-invasive way, images from the interior of the human body through tomographic mapping of radioactive material administered to the patient. The SPECT systems are based on the Gamma Camera detection system, and one of them being set on a rotational gantry is enough to obtain the necessary data for a tomographic image. The images obtained from the SPECT system consist in a group of flat images that describe the radioactive distribution on the patient. The trans-axial cuts are obtained from the tomographic reconstruction techniques. There are analytic and iterative methods to obtain the tomographic reconstruction. The analytic methods are based on the Fourier Cut Theorem (FCT), while the iterative methods search for numeric solutions to solve the equations from the projections. Within the analytic methods, the filtered backprojection (FBP) method maybe is the simplest of all the tomographic reconstruction techniques. This paper's goal is to present the operation of the SPECT system, the Gamma Camera detection system, some tomographic reconstruction techniques and the requisites for the implementation of this system in a Nuclear Medicine service

Optimal Timing for Assessment of Tumor Response to Neoadjuvant Chemoradiation in Patients With Rectal Cancer: Do All Patients Benefit From Waiting Longer Than 6 Weeks?

Purpose: To estimate the metabolic activity of rectal cancers at 6 and 12 weeks after completion of chemoradiation therapy (CRT) by 2-[fluorine-18] fluoro-2-deoxy-D-glucose-labeled positron emission tomography/computed tomography ([18 FDG] PET/CT) imaging and correlate with response to CRT. Methods and Materials: Patients with cT2-4N0-2M0 distal rectal adenocarcinoma treated with long-course neoadjuvant CRT (54 Gy, 5-fluouracil-based) were prospectively studied (ClinicalTrials. org identifier NCT00254683). All patients underwent 3 PET/CT studies (at baseline and 6 and 12 weeks fromCRT completion). Clinical assessment was at 12 weeks. Maximal standard uptakevalue (SUVmax) of the primary tumor wasmeasured and recorded at eachPET/CTstudy after 1 h (early) and3 h (late) from 18 FDGinjection. Patientswith an increase in early SUVmax between 6 and 12 weeks were considered " bad" responders and the others as "good" responders. Results: Ninety-one patients were included; 46 patients (51%) were "bad" responders, whereas 45 (49%) patients were " good" responders. " Bad" responders were less likely to develop complete clinical response (6.5% vs. 37.8%, respectively; PZ. 001), less likely to develop significant histological tumor regression (complete or near-complete pathological response; 16% vs. 45%, respectively; PZ. 008) and exhibited greater final tumor dimension (4.3cmvs. 3.3cm; PZ. 03). Decrease between early (1 h) and late (3 h) SUVmax at 6-week PET/CTwas a significant predictor of " good" response (accuracy of 67%). Conclusions: Patients who developed an increase in SUVmax after 6 weeks were less likely to develop significant tumor downstaging. Early-late SUVmax variation at 6-week PET/CT may help identify these patients and allow tailored selection of CRT-surgery intervals for individual patients. (C) 2012 Elsevier Inc.

A tomografia por emissão de pósitrons com 2-[18F]-fluoro-2-desoxi-D-glicose é custo-efetiva em pacientes com câncer de pulmão não pequenas células no Brasil

OBJETIVO: Comparar a acurácia e a custo-efetividade do estadiamento metabólico (EM) com o FDG-PET em relação ao estadiamento convencional (EC) no estadiamento inicial de pacientes com câncer de pulmão não pequenas células (CPNPC). MATERIAIS E MÉTODOS: Noventa e cinco pacientes com diagnóstico inicial de CPNPC foram estadiados antes do início do tratamento. Os resultados do EC e EM foram comparados quanto a definição do tratamento e incidência de toracotomia fútil em cada estratégia. RESULTADOS: O EM com FDG-PET classificou 48,4% dos pacientes como estádio mais avançado e 5,3% como menos avançado. O resultado do EM modificaria o tratamento em 41% dos pacientes. A toracotomia foi considerada fútil em 47% dos pacientes com EC e em 19% dos casos com EM. O custo das toracotomias fúteis em oito pacientes no EM foi de R$ 79.720, enquanto em 31 pacientes no EC seria de R$ 308.915. Apenas esta economia seria mais que suficiente para cobrir os custos de todos os exames de FDG-PET nos 95 pacientes (R$ 126.350) ou de FDG-PET/CT (R$ 193.515). CONCLUSÃO: O EM com FDG-PET tem maior acurácia que o EC em pacientes com CPNPC. A FDG-PET e FDG-PET/CT são custo-efetivas e sua utilização se justifica economicamente na saúde pública no Brasil.

Studio di fattibilità della produzione diretta di tc-99m mediante ciclotrone

Le caratteristiche del 99mTc e la possibilità per gli ospedali di produrlo in loco quotidianamente grazie ai generatori, hanno reso questo radioisotopo il più utilizzato della fisica medica: è richiesto in circa l’80% delle procedure di medicina nucleare con circa 7 milioni di somministrazioni all’anno in Europa e 8 milioni negli USA. Inoltre il campo di applicabilità del 99mTc è molto vasto: viene infatti utilizzato per scintigrafie ossee, epatiche, renali, celebrali, tiroidee e per il controllo della funzionalità epatica. A causa del notevole incremento dell’insorgenza di patologie oncologiche e dell’aumento della popolazione, la richiesta di 99mTc è sempre cresciuta negli anni ed è ancora destinata a crescere nei prossimi; l’unico fattore attenuante è lo sviluppo di altre tecniche di diagnostica funzionale come la PET ( Positron Emission Tomography ). Nonostante la creazione del 99mTc da generatori di 99Mo sia ancora oggi il metodo di produzione più efficiente, si sta ponendo recentemente la necessità di ricercare nuove tecniche di produzione dell’isotopo per soddisfare le grandi quantità richieste dal mercato globale. Questo accade perché malgrado l’utilizzo del 99mTc sia in forte crescita, la produzione di 99Mo è destinata a diminuire in quanto necessita di reattori nucleari: gli ingenti costi delle moderne centrali e le elevate quantità di scorie prodotte, stanno guidando la politica mondiale verso una denuclearizzazione che renderà in pochi anni impossibile soddisfare la richiesta di 99Mo della medicina nucleare. Questo lavoro di tesi si colloca in questo contesto, cioè nella ricerca di un metodo alternativo per la produzione di 99mTc: l’irraggiamento con protoni di un target di 100Mo arricchito, in un ciclotrone ad uso medicale. L’obbiettivo che si vuole raggiungere è fornire una stima attendibile su tale produzione, valutare la qualità dell’isotopo e mettere in luce eventuali problematiche riscontrabili.

Development and optimisation of novel 68 Ga-folates - towards early diagnosis of ovarian cancer

Der Folsäure-basierte Radiotracer Etarfolatide (99mTc-EC 20) hat in der Vergangenheit sehr vielversprechende Ergebnisse im Bereich der frühzeitigen Diagnostik von Ovarialkarzinomen gezeigt. Einzelphotonen-Emissionscomputertomographie (SPECT) erlaubt dabei eine Visualisierung der Krankheit in einem sehr frühen Stadium – ermöglicht wird dies durch Folsäure, welche als Target Vektor dient. Um das erfolgreiche Prinzip der Radiofolate auf die Positronen-Emissionstomographie (PET) zu übertragen, welche eine noch höhere räumliche Auflösung ermöglicht, wurden in den letzten fünf Jahren bereits 18F-folate entwickelt. Deren hepatobiliären Exkretionsmuster, verursacht durch die relativ hohe Lipophilie der Strukturen, entsprachen jedoch nicht den Anforderungen. Eine optimierte Bioverteilung der Tracer in vivo kann durch eine generelle Erhöhung der Polarität erfolgen. Die Kombination aus einem polaren 68Ga-Komplex mit Folsäure als Target Vektor stellte den Fokus dieses Projektes dar. Ziel war die Entwicklung eines Radiofolates mit der Tendenz einer raschen renalen Ausscheidung und verringerter hepatobiliärer Anreicherung. Dazu wurde Folsäure regiospezifisch über ihre y-Säure an verschiedene bifunktionelle Chelatoren (BFCs) gekoppelt. Vier verschiedene Reaktionstypen wurden gewählt und durchgeführt: Cu-katalysierte sowie Cu-freie Click Reaktion, Amindbindung und Thioharnstoff Bildung. Es wurden sechs verschiedene Derivate erhalten und mit 68Ga radiomarkiert.

Glykopolymere für biomedizinsche Anwendungen : Synthese von mannosylierten N-(2-Hydroxyprpyl)methacrylamid Polymersystemen für die Adressierung von Zellen des Immunsystems

Das Ziel dieser Arbeit lag darin mannosylierte Polymersysteme hauptsächlich auf der Basis von N-(Hydroxy)propylmethacrylat zu synthetisieren, um gezielt Zellen des Immunsystems zu adressieren. Dazu wurden zunächst verschiedene Reaktivesterpolymere auf der Basis von Pentafluorophenylmethacrylat (PFPMA) unter Verwendung der RAFT-Polymerisation mit enger Molekulargewichtsverteilung und unterschiedlichen Anteilen an LMA (Laurylmethacrylat) hergestellt.rnUm eine genaue Aussage über den Aufbau eines statistischen PFPMA-LMA Copolymers treffen zu können, wurde die Copolymerisation von PFPMA und LMA mittels Echtzeit 1H-NMR Kinetikmessungen untersucht. Dies ermöglichte es, die Copolymerisationsparameter zu berechnen und genaue Aussagen über den Aufbau eines statistischen PFPMA-LMA Copolymers zu treffen. Die so erhaltenen Reaktivesterpolymere wurden dann in einer polymeranalogen Reaktion unter Erhalt des Polymerisationsgrades in die gewünschten HPMA-Polymere umgewandelt. Um die quantitative Umsetzung ohne auftretende Nebenreaktionen zu untersuchen, wurden verschiedene Reaktionsbedingungen gewählt und unterschiedliche Analysemethoden verwendet. Damit konnte gezeigt werden, dass es möglich ist, über den Reaktivesteransatz qualitativ hochwertige amphiphile Polymersysteme herzustellen, die auf anderen Wegen schwer zu synthetisieren und charakterisieren sind. Ein weiterer Vorteil dieser Syntheseroute ist, dass gleichzeitig sowohl Marker für die Visualisierung der Polymere in vitro und in vivo, als auch Targetliganden für die Adressierung bestimmter Zellen eingeführt werden können. Dafür wurde hauptsächlich Mannose als einfache Zuckerstruktur angebunden, da bekannt ist, dass mannosylierte Polymersysteme von Zellen des Imunsystems aufgenommen werden. Zusätzlich konnten die mannosylierten Polymere mit hydrophobem Wirkstoff beladen werden, wobei die Stabilität von beladenen Mizellen anhand der Einlagerung eines hydrophoben radioaktiven Komplexes genauer untersucht werden konnte.rnAnschließende in vitro Experimente der mannosylierten Polymermizellen an dendritischen Zellen zeigten wie erwartet eine mannosespezifische und verstärkte Aufnahme. Für eine mögliche Untersuchung dieser Systeme in vivo mittels PET konnte gezeigt werden, dass es möglich ist HPMA Polymere radioaktiv zu markieren, wobei auch erste Markierungsversuche mit einem langlebigen Radionuklid für Langzeitbiodistributionsstudien durchgeführt werden konnte.rn

18F-fluorodeoxyglucose uptake of bone and soft tissue sarcomas in pediatric patients

A high (18)F-fluorodeoxyglucose (FDG) uptake by positron emission tomography/computed tomography (PET/CT) imaging in sarcomas of adults has been reported. The current study aimed at defining the degree of (18)F-FDG uptake of pediatric sarcomas. This retrospective study included 29 patients (23 males, 6 females; mean age 14 ± 5 years) with soft tissue (n = 9) or bone (n = 20) sarcomas. Twenty-two patients (76%) underwent (18)F-FDG PET/CT and 7 (24%) had dedicated (18)F-FDG PET studies. Tumor (18)F-FDG uptake was quantified by standard uptake value (SUV)(max) and tumor-to-liver ratios (SUV ratios; tumor SUV(max)/liver SUV(mean)). Tumor SUV(max) and SUV ratios were correlated with tumor Ki-67 expression. SUV(max) ranged from 1.4 to 24 g/mL (median 2.5 g/mL) in soft tissue sarcomas and 1.6 to 20.4 g/mL (median 6.9 g/mL) in bone sarcomas (P = .03), and from 1.6 to 9.2 g/mL (median 3.9 g/mL) and 3.5 to 20.4 g/mL (median 12 g/mL) in Ewing sarcoma and osteosarcoma, respectively (P = .009). Tumor SUV ratios ranged from 0.8 to 8.7 (median 1.9) in soft tissue sarcomas and 1.4 to 8.9 (median 3.8) in bone sarcomas (P = .08). Ewing sarcoma had a significantly lower tumor SUV ratio than osteosarcoma (P = .01). Ki-67 expression correlated significantly with the (18)F-FDG uptake in bone but not in soft tissue sarcomas. All sarcomas were visualized by (18)F-FDG PET/CT imaging. A higher (18)F-FDG uptake was observed in osteosarcoma than in Ewing and soft tissue sarcomas. The results of this study suggest that the degree of tumor (18)F-FDG uptake is sufficient to allow for monitoring of therapeutic responses in pediatric sarcomas.