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La tomographie d’emission de positons couplee a la tomodensitometrie (TEP/TDM) est une modalite d’imagerie medicale qui fournit la distribution tridimensionnelle d’une molecule marquee par un emetteur de positons et l’anatomie associee. L’acquisition est realisee par un ensemble de detecteurs repartis autour du patient. Les detecteurs sont bases sur un scintillateur qui est choisi en fonction de nombreuses proprietes pour ameliorer l’efficacite et le rapport signal sur bruit. Le circuit de coincidence mesure les deux photons d’annihilation de 511 keV emis dans des directions opposees qui resultent de l’annihilation du positon. Les coupes sont reconstruites par des algorithmes de plus en plus complexes. La correction des phenomenes physiques fournit une image representative de la distribution du traceur. Un examen TEP/TDM entraine pour le patient une dose efficace de l’ordre de 15 mSv. L’installation d’une TEP/TDM necessite un amenagement des locaux pour assurer la radioprotection du personnel. Cette technique est en evolution permanente, tant au plan du detecteur et du cristal que de celui des algorithmes de reconstruction de l’image. Tous ces developpements font de la TEP/TDM un outil pleinement operationnel, qui a toute sa place au sein de l’imagerie medicale.

Resume La radiopharmacie est une activite de pharmacie hospitaliere qui utilise des sources radioactives non scellees pour la preparation des medicaments radiopharmaceutiques utilises en medecine nucleaire. L’exposition aux rayonnements ionisants et le risque de contamination interne et cutanee lies a cette activite imposent de mettre en œuvre des moyens de radioprotection qui decoulent des regles generales de radioprotection pour la manipulation de sources non scellees. Les modalites pratiques de mise en œuvre doivent etre definies pour chacune des etapes du circuit des medicaments radiopharmaceutiques : reception des produits, preparation des medicaments, controle des preparations, dispensation des doses et gestion des dechets. Par ailleurs, la conduite a tenir en cas d’incident doit etre prevue, qu’il s’agisse d’une contamination de surface ou d’une contamination humaine. Parallelement, les personnels affectes en radiopharmacie doivent faire l’objet d’une surveillance medicale renforcee et d’un suivi dosimetrique, afin de s’assurer de l’efficacite des mesures de radioprotection et du respect des limites d’exposition.

Recemment introduite dans la pratique clinique, la tomographie par emission de positons (TEP) au 18F-fluorodeoxyglucose (FDG) a trouve sa place dans le diagnostic et le bilan d’extension des affections cancereuses en raison de son aptitude a la caracterisation tissulaire des lesions. Son utilisation evolue vers l’evaluation de l’effet anti-tumoral des traitements anticancereux, en raison de la correlation entre la fixation d’un traceur metabolique et la viabilite des cellules malignes. Le fait que les effets metaboliques soient les premiers a etre induits par une chimiotherapie explique la precocite de l’information TEP quant a l’activite d’un traitement. Cependant, l’evaluation de l’efficacite therapeutique par TEP-FDG necessite une methodologie rigoureuse et doit prendre en compte les limites de la methode de quantification par le standardized uptake value (SUV). Par ailleurs, afin de depasser les limites du FDG, des traceurs plus specifiques sont developpes, et leur principale indication pourrait justement concerner l’evaluation de l’efficacite therapeutique. Les proprietes des emetteurs de positons permettent d’envisager le marquage des molecules therapeutiques elles-memes afin de tester in vivo les produits avant leur utilisation chez un patient donne. Ces perspectives constituent les bases d’une veritable personnalisation des traitements en cancerologie. Elles ouvrent un champ de recherche clinique immense, mais contribuer a ce mouvement impose de disposer des moyens necessaires pour l’imagerie et surtout pour la production des traceurs radioactifs. Compte tenu des performances actuelles des systemes TEP, le point reellement critique est la disponibilite des equipements permettant la conception et la synthese des radiopharmaceutiques de l’avenir.

Gli esami di medicina nucleare, in quanto tecniche di imaging funzionale e metabolico, hanno un ruolo sempre piu grande nell’arsenale diagnostico a disposizione del medico otorinolaringoiatra (ORL). La tomografia a emissione di positroni (PET), ormai sistematicamente accoppiata alla TCX, con fluorodesossiglucosio (FDG) rivoluziona il trattamento dei pazienti portatori di affezioni neoplastiche, specialmente in ORL, dove la percentuale dei carcinomi epidermoidi e predominante. Molto efficace nel bilancio di estensione linfonodale regionale o a distanza, come per la diagnosi delle neoplasie sincrone, il suo ruolo e destinato a divenire fondamentale per la ricerca di lesioni residue e per l’individuazione precoce delle recidive. Anche la valutazione della risposta dei tumori ai trattamenti chemioterapici e l’ottimizzazione dei campi e della dosimetria nella radioterapia risultano essere applicazioni con molte prospettive, tanto piu che la tecnica mediante PET e in costante evoluzione. Riguardo alla medicina nucleare monofotonica, la tecnica del linfonodo sentinella e in pieno sviluppo, in particolare per la gestione delle lesioni della cavita orale senza alcun interessamento linfonodale clinico o radiologico. Permette di evitare uno svuotamento linfonodale selettivo nei tre quarti dei pazienti, riducendo cosi la morbilita, la durata e il costo del trattamento con la stessa sicurezza oncologica. Infine, altre tecniche piu classiche sono tuttora di attualita, che si tratti della tomoscintigrafia ossea con difosfonati al tecnezio e della scintigrafia al gallio 67 per la valutazione dell’efficacia del trattamento dell’otite maligna esterna, della scintigrafia delle paratiroidi per la ricerca degli adenomi paratiroidei nella valutazione preoperatoria o, ancora, della sialoscintigrafia per la valutazione funzionale delle ghiandole salivari.

Las exploraciones de medicina nuclear en sus variantes de tecnicas de imagen funcional y metabolica ocupan un papel cada vez mayor en el arsenal diagnostico del que dispone el medico otorrinolaringologo (ORL). La tomografia por emision de positrones (PET) (que en la actualidad se acopla de forma sistematica a una tomografia computarizada [TC] de rayos X) con fluorodesoxiglucosa (FDG) ha revolucionado el tratamiento de los pacientes portadores de afecciones neoplasicas, sobre todo ORL, donde la proporcion de los carcinomas epidermoides es predominante. Esta tecnica es muy rentable para el estudio de extension ganglionar regional o a distancia, asi como para la deteccion de neoplasias sincronicas; en el futuro, ocupara un papel primordial para la busqueda de lesiones residuales, asi como para la deteccion precoz de las recidivas. La evaluacion de la respuesta de los tumores a los tratamientos de quimioterapia y la optimizacion de los campos y de la dosimetria en radioterapia tambien son unas aplicaciones con un gran futuro, sobre todo porque la PET esta en evolucion constante. Respecto a la medicina nuclear monofotonica, la tecnica del ganglio centinela esta en pleno auge, sobre todo para el tratamiento de las lesiones de la cavidad bucal sin afectacion ganglionar clinica o radiologica. Permite evitar un vaciamiento ganglionar selectivo en alrededor del 75% de los pacientes, lo que disminuye la morbilidad, la duracion y el coste del tratamiento, con la misma seguridad oncologica. Por ultimo, otras tecnicas mas clasicas siguen de actualidad, como la tomogammagrafia osea con bisfosfonatos marcados con tecnecio y la gammagrafia con galio 67 para la evaluacion de la eficacia del tratamiento de la otitis externa maligna, la gammagrafia de las glandulas paratiroides para la busqueda de adenomas paratiroideos en el estudio preoperatorio o, incluso, la sialogammagrafia para la valoracion funcional de las glandulas salivales.

Key points FDG-PET is now an established diagnostic tool in oncology. Fluorodeoxyglucose is not a specific tracer for malignant lesions but rather for elevated glucose metabolism, present not only in cancer but also in inflammatory and infectious lesions. FDG-PET has thus been suggested for diagnosis of fevers of unknown origin, deep bone or visceral infectious foci, inflammatory vasculitis or sarcoidosis and unknown primary tumors, all frequent situation in internal medicine. The main characteristics of FDG-PET are its ability to rule out focal inflammation or infection with a high degree of certainty when the examination is negative because of its good negative predictive value and its usefulness as an early marker of therapeutic response, compared with anatomy-based or conventional scintigraphic imaging. Large-scale prospective studies are necessary, however, before FDG-PET is integrated into routine clinical use. It should be compared with different techniques already validated (biology, radiology, conventional scintigraphic imaging) and its cost-effectiveness should be evaluated.

DESIGN: This study is a preliminary report on 18F-fluorodeoxyglucose (18F-FDG) uptake for the characterization of hypersecretory or non-hypersecretory adrenocortical masses in patients without known neoplastic disease, thereby minimizing the presence of adrenal metastases, and without phaeochromocytoma, in comparison with computed tomography (CT) scanning and with iodocholesterol scintigraphy. METHODS: Thirteen consecutive patients with an adrenal mass scheduled to have surgery, underwent hormonal exploration, a CT scan for tumour size measurement and an 18F-FDG positron emission tomography scan. Eleven of these patients also had unenhanced density measurement at CT scan and iodocholesterol scintigraphy. RESULTS: CT-scanned adrenal masses ranged in size from 2.2 to 10 cm; attenuation value was 10 HU in nine. All benign lesions demonstrated iodocholesterol uptake. In the case of malignant tumours, results were non-homogeneous: no uptake, uptake and non-informative scintigraphy. All patients with an adrenocortical carcinoma had positive adrenal 18F-FDG uptake (n=3), one had a liver metastasis with positive 18F-FDG uptake, one showed 18F-FDG uptake in an adrenal metastasis from an unknown primary kidney tumour. All patients with a benign adrenocortical lesion had negative 18F-FDG uptake (n=9). Patients' lesions were hypersecretory (n=5), or non-hypersecretory (n=8), regardless of the pathology. CONCLUSION: This short preliminary study indicates that 18F-FDG gave a correct classification of tissue characterization with accurate identification of malignant lesions, as well as the disease stage (metastasis or primary). These promising preliminary results on adrenocortical lesions, seldom studied with 18F-FDG, are to be confirmed in larger series.

Kaposi sarcoma (KS) is a tumor caused by human herpesvirus 8, also known as KS-associated herpesvirus. Epidemiological varieties are represented by an epidemic form, strongly associated with AIDS, classic form, endemic form, and transplant-related form in association with severely immunosuppressive drug regimens, pointing to a role for immunodeficiency in the development of KS. We report the case of a woman who had preexisting immune system damage because of recurrent Hodgkin's lymphoma and presented with KS of the pelvis with high FDG uptake on PET/CT mimicking nodal relapse. Clinicians and nuclear medicine physicians should be aware that KS can present as intense FDG uptake. Moreover, our case emphasizes the importance of obtaining a biopsy.

L'essor des techniques d'imagerie fonctionnelle depuis une quinzaine d'annees a profondement modifie la maniere d'aborder la cartographie fonctionnelle du cerveau humain. Il a conduit a l'emergence de vastes projets confrontes a la manipulation d'enormes quantites de donnees anatomo-fonctionnelles. Ces projets impliquent la possibilite de comparer des individus et de thesauriser les resultats obtenus en matiere de localisation anatomique par rapport a un referentiel.

An 82-year-old woman was followed up for an uterine cervical adenocarcinoma treated by surgery. A whole-body fluorodeoxyglucose positron emission tomography study revealed a pathologic fluorodeoxyglucose uptake located in the umbilicus associated to peritoneal carcinomatosis. Biopsy of the umbilical nodule demonstrated an umbilical metastasis from the uterine adenocarcinoma, the so-called "Sister Mary Joseph's nodule."

Context: Most adrenal incidentalomas are nonfunctioning adrenocortical adenomas (ACAs). Adrenocortical carcinomas (ACCs) are rare but should be recognized at an early stage. Objective: The objective of the study was to evaluate the usefulness of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) to predict malignancy in patients without a previous history of cancer. Design: This was a prospective, multicenter study from 2001 to 2006. Setting: The study was conducted at a network of seven university hospitals in Paris. Patients: Seventy-seven patients were included. All underwent surgery because of hypersecretory and/or growing benign lesions (n = 18), obvious ACCs (n = 21), or radiologically indeterminate lesions (n = 38). Main Outcome Measure: The degree of 18F-FDG PET uptake [maximum standardized uptake value (maxSUV)] was related to the pathological findings serving as a reference, and its diagnostic value was compared with that of computerized tomography (CT) scan. Results: Pathology eventually diagnosed 43 ACAs, 22 ACCs, and 12 nonadrenocortical lesions. Using a cutoff value above 1.45 for adrenal to liver maxSUV ratio, the sensitivity and specificity to distinguish ACAs from ACCs were, respectively, 1.00 (95% confidence interval 0.85–1.00) and 0.88 (95% confidence interval 0.75–0.96). Among the 38 indeterminate lesions at CT scan, we could analyze a subgroup of 16 adrenocortical tumors with high unenhanced density (>10 HU) and an inappropriate washout: 18F-FDG PET correctly predicted the benignity in 13 of 15 ACAs. Conclusions: In a multidisciplinary team approach, 18F-FDG PET helps to manage suspicious CT scan lesions. An adrenal to liver maxSUV ratio less than 1.45 is highly predictive of a benign lesion.

Granulocytic sarcoma (GS) is a rare disease corresponding to extramedullary tumor mostly associated with acute myelogenous leukemia. Despite the aggressiveness of leukemic cells, F-18-FDG PET is not recommended for leukemia but it may have relevance for these tumors with solid and malignant

This prospective and bi-centric study was conducted in order to determine the impact of antidiabetic treatments (AD) on (18)F-FDG bowel uptake in type 2 diabetic patients.Fifty-five patients with previously diagnosed and treated type 2 diabetes mellitus (group 1) were divided in two subgroups: AD treatment including metformin (n=32; group 1a) and AD treatment excluding metformin (n=23; group 1b). The 95 patients without diabetes mellitus made up controls (group 2). (18)F-FDG uptake in small intestine and colon was visually graded and semi-quantitatively measured using the maximum standardized uptake value.(18)F-FDG bowel uptake was significantly increased in AD patients (group 1) as compared to controls (group 2) (p0.001). Bowel uptake was significantly higher in AD patients including metformin (group 1a) as compared to AD patients excluding metformin (group 1b) (p0.01), whose bowel uptake was not significantly different from controls (group 2). A metformin treatment was predictive of an increased bowel uptake in the small intestine (odds ratio OR=16.9, p0.0001) and in the colon (OR=95.3, p0.0001), independently of the other factors considered in the multivariate analysis. Bowel uptake pattern in the patients treated with metformin was typically intense, diffuse and continuous along the bowel, strongly predominant in the colon, in both the digestive wall and lumen.This study emphasizes that metformin significantly increases (18)F-FDG uptake in colon and, to a lesser extent, in small intestine. It raises the question of stopping metformin treatment before an (18)F-FDG PET/CT scan is performed for intra-abdominal neoplasic lesion assessment.

Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) represent 15 – 20% of all malignancies in children [1]. One of the major problems for clinicians is the presence of radiological or clinical res...

63 Background: Circulating tumor cells (CTCs) and FCH PET/CT are both promising tools for treatment monitoring in CRPC pts. In this study, we assessed prostate specific antigen (PSA), CTC and FCH PET/CT for monitoring treatment response in metastatic CRPC pts receiving recently approved abiraterone acetate therapy after chemotherapy. Methods: Twenty nine metastatic CRPC pts progressing after docetaxel chemotherapy received abiraterone acetate 1,000 mg daily with prednisone 5 mg twice daily in continuous 28-day cycles. Pts were evaluated monthly for efficacy and safety. CTCs counts (using the CellSearch assay) and FCH PET/CT were performed at baseline and at 4 weeks (PERCIST criteria and SUV Peak). Results: After one month of treatment, 12 pts (41%) had a PSA rise and 17 pts (59%) had a PSA decline. At baseline, 18 pts had detectable CTCs (at least 5 CTCs), and 6 of them (33%) had a decline from at least 5 to less than 5 CTCs after 4 weeks of treatment. 10 of 29 pts (34%) had a > or = 30% decline in CTCs. Amongst 22 pts who were evaluable by FCH PET/CT, response assessment was as follows: response (n=8), stable disease (n=12), progression (n=1). PSA decline and CTCs levels correlated in 16 of 29 pts (55%), and were discordant in 13 of 29 pts (45%). In all 12/29 pts (41%) with a 50% or more decline in PSA both a CTCs response and a FCH PET/CT response was observed. In patients with a PSA rise while on abiraterone acetate, 8 pts did not have a CTCs increase or a CTC conversion from unfavourable to favorable, and 7 of 8 pts had a PSA decline at 3 months or a FCH PET/CT response. No flare phenomenon on FCH PET/CT was observed. Conclusions: Monitoring pts with CRPC who receive abiraterone using both CTCs and metabolic imaging indicate discrepancy in 45% with response assessment using PSA. Association between CTC drop, early FCH PET/CT response and clinical benefit is currently under study.