Apport de la TEP-FDG dans le staging initial des cancers du sein localement avancés traités par chimiothérapie néo-adjuvante

Axillary lymph node and distant metastases are unfavourable prognostic factors in breast cancer. The aim of our study was to evaluate the performance of PET-FDG in the staging of locally advanced breast cancer (LABC) treated with neoadjuvant chemotherapy (NAC) and surgery, and to compare the findings of pretherapeutic PET to those of axillary nodal status obtained by surgery after NAC (Sataloff classification). This retrospective study involved 89 patients with LABC explored at presentation by PET in addition to conventional clinical and imaging staging (CS). Breast cancer excision and axillary dissection were performed after NAC. PET and CS found an axillary involvement in 58 patients (65%) and 39 patients (44%), respectively. Compared to the histology of post-NAC axillary dissection, PET had sensitivity and specificity of 80% and 63%, respectively. PET revealed an extra-axillary lymph node involvement, not suspected by the CS, in 25 patients (28%). Bone and lung metastases, not suspected by the CS were found in two and one patients, respectively. A case of false-positive PET in the liver was observed (adenomatosis). This study confirms the value of PET in the initial staging of LABC, especially in assessing extra-axillary nodal status. In the determination of axillary status, PET has a high positive predictive value, cases of doubtful interpretation suggesting to perform ultrasound-guided fine needle aspiration in addition.     

Rôle de la TEP au 18F-FDG dans l’évaluation des volumes cibles chez des patients atteints de CBNPC traités par radiochimiothérapie

Currently ¹⁸F-FDG-PET is the gold standard to evaluate tumor response after chemotherapy in patients with advanced or metastatic non-small cell lung cancer (NSCLC). PET can also determine the volumes to be treated by radiotherapy, in inoperable patients. The aim of our mixed (prospective and retrospective) study concerned 28 patients with NSCLC, was to quantify the variation of the metabolic activity of lesions and their volumes after chemotherapy. We also studied the impact of change of these volumes on the definition of radiotherapy target volumes. Patients with stage II–IV and inoperable NSCLC were included. Two PET scans were performed: before treatment (PET1), then after two to six courses of chemotherapy (PET2). Of the 28 patients included, we observed complete metabolic response in six patients (21%), partial metabolic response in 13 patients (46%), stable disease in seven patients (25%), and progressive metabolic disease in two patients (7%), according to the PERCIST criteria. We observed significant variation (P < 0.001) of metabolic activity (estimated by SULpeak or SUVmax) for primary tumor as well as for overall lesions between the two PET scans. Thus, the target volumes of radiotherapy decreased significantly (P < 0.01) in PET2. Our results confirm that ¹⁸F-FDG-PET is not only a powerful technique for treatment evaluation but also a useful tool for radiotherapy planning after chemotherapy, in the context of personalized treatments.     

Apport de la TEP/TDM au 18FDG dans la stadification initiale et l’évaluation précoce de la réponse thérapeutique des rhabdomyosarcomes pédiatriques

PurposeThe objective of this study was to retrospectively evaluate the impact of positron emission tomography/computed tomography (PET/CT) using fluorine-18-fluorodeoxyglucose (FDG), in comparison with conventional imaging modalities (CIM), for initial staging and early therapy assessment in paediatric rhabdomyosarcoma.Patients and methodsPrior to treatment, 18 patients (age range, 9 months to 18 years) with histologically proven rhabdomyosarcoma underwent FDG PET/CT in addition to CIM (magnetic resonance imaging of primary site, whole body CT and bone scintigraphy). After three courses of chemotherapy, 12 patients underwent FDG PET/CT in addition to CIM. RECIST criteria and visual analysis of FDG uptake were used for assessment of response. The standard of reference was determined by an interdisciplinary tumor board based on imaging material, histopathology and follow-up data (median = 5 years).ResultsPET/CT sensitivity was superior to CIM's concerning lymph node involvement (100% versus 83%, respectively) and metastases detection (100% versus 50%, respectively). PET/CT results changed therapeutic management in 11% of cases. After three courses of chemotherapy, the rate of complete response was 66% with PET/CT versus 8% with CIM. Five percent of patients relapsed during follow-up (median = 5 years).ConclusionThis study confirms that PET/CT depicts important additional information in initial staging of paediatric rhabdomyosarcomas and suggests a superior prognostic value of PET/CT in early response to chemotherapy assessment.     

Intérêt complémentaire de la TEP/TDM au FDG et de l’imagerie conventionnelle dans le bilan initial et le suivi post-thérapeutique des cancers des VADS : recommandations et perspectives

Functional imaging by ¹⁸fluorodesoxyglucose (FDG) positron emission tomography (PET) and morphological imaging by computed tomography (CT) and magnetic resonance imaging (MRI) hold an important and complementary role in characterization of head and neck squamous cell carcinoma (HNSCC). Based on an exhaustive literature, the recommendations and perspectives of their use in the initial assessment and the post-therapeutic management of HNSCC are presented.     

Découverte fortuite de fixations colorectales focales du FDG en TEP/TDM : corrélation aux données de la coloscopie

PurposeFDG-PET is an established tool for the diagnosis of recurrent or metastatic colorectal carcinoma. Several case series suggest that FDG-PET often detects incidental adenomatous polyps or colorectal adenocarcinomas. The aim of this study was to correlate unexpected colorectal foci of FDG uptake to pathology findings after systematic colonoscopy.Patients and methodsWe reviewed the records of 3541 patients who underwent FDG PET/CT in our institution over a 30-month period for the assessment of a known or suspected malignancy. In 85 of them, incidental, nodular shaped and well-circumscribed foci of abnormal uptake were identified in the area of the colon or rectum. Patients with segmental or diffuse abnormal colorectal uptake were excluded, as well as patients with known benign or malignant colorectal disease. Colonoscopy and complete pathology report was available in 29 patients. Maximal standardized uptake value (SUV_max) was measured in all lesions.ResultsUnexpected colorectal foci of FDG uptake were associated with colonoscopic abnormalities in 23 patients (true positive rate: 79 %). Adenocarcinomas were found in six patients (SUV_max = 7.3 ± 2.6), tubulous adenomas in four patients (SUV_max = 7.3 ± 4.9) and tubulovillous adenomas in 12 patients (SUV_max = 4.2 ± 1.1). Hyperplasic polyps with no sign of dysplasia were found in the last patient (SUV_max = 3.3). Concomitant CT abnormalities were found on PET/CT fusion in eight patients and consisted of wall thickening (n = 5) or nodular mass (n = 3). Conversely, PET was falsely positive in six patients (21 %), with no concomitant CT abnormalities and no abnormal findings at endoscopy (SUV_max = 6.2 ± 2.8, no significant difference with true positive lesions).ConclusionOur findings emphasize the need to perform a colonoscopy in front of incidental nodular colorectal foci of FDG uptake because malignant or pre-malignant neoplasms, which are not clinically apparent, are found in more than three-quarter of cases.     

Place de la TEP au FDG dans le bilan des épilepsies pharmacorésistantes

The work-up of drug-resistant partial epilepsy is intended to localize epileptogenic foci in the purpose of a possible surgery. We aimed to assess the role of fluorodeoxyglucose Positron Emission Tomography (FDG PET) in this scope. This study involved 34 patients who underwent brain FDG PET, with a final diagnosis in 21. The value of FDG PET for lateralisation and localisation of the epileptogenic focus was evaluated by a blinded interpretation, and compared with the value of standard investigations. The impact of FDG PET was assessed by the means of a questionary intended for the neurologist in each case. All the epilepsy types together, FDG PET lateralised and localised the foci in 65 and 47% of the 34 subjects respectively. Among the 19 subjects with final diagnosis (patients with bilateral foci excluded), lateralisation was correct in 84% and localisation in 63% (and the values were greater for temporal epilepsy than for extratemporal foci). PET frequently provided additional information compared with MRI, but not with EEG. FDG PET was useful in 82.5% of cases (confirming management in 65% and changing it in 17.5% of the patients). Our experience corroborated the value of FDG PET for lateralisation and localisation of epileptogenic foci, and its role in case of normal MRI. However, FDG PET appears as a confirmation tool rather than an examination resulting in a change in management rate.     

Apport du 68Ga-PSMA-TEP dans la prise en charge initiale par radiothérapie des cancers de la prostate

Radiotherapy is one of major modality for prostate cancer treatment. Technical improvements allow to deliver higher doses to the tumor, and improve protection of healthy tissues. Those improvements are enlarging indications and change treatment modalities for prostate cancer patients, on primary staging or at time of relapse (local or metastatic). Accounting to recent publications, 68Ga-PSMA PET should have an impact on radiotherapy treatment planning for those patients, especially in case of intermediate to high risk tumor. In case of metastatic disease, early detection of metastasis allows selection of patients with oligo-metastatic cancer for whom local treatments are in development. For localized prostate cancer, diagnosis of nodal extension permit volumes and doses modifications for radiotherapy. An accurate detection of the dominant intra-prostatic lesion gives the possibility of a focalized dose escalation to this significant cancer (“index lesions”). This new treatment strategies coming from technical progress are currently evaluated to assess their clinical benefit.     

Bilan initial d’imagerie de l’adénocarcinome pancréatique : données de la littérature sur la place actuelle de la tomographie par émission de positons au 18F-fluorodéoxyglucose (TEP FDG)

In pancreatic adenocarcinoma, initial imaging is essential to better select patients for surgery. Recent literature analysis of F18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET) in pancreatic adenocarcinoma is summarized in the present article. Performances of FDG PET in the fields of lymph node involvement, metastatic involvement and therapeutic efficacy assessment are described for its correct use in pancreatic adenocarcinoma.     

Les carcinomes papillaires de la thyroïde révélés par examen TEP/TDM au 18F-FDG : à propos de deux cas et revue de la littérature

The authors report the cases of two patients followed up for Hodgkin lymphoma, whose control PET/CT during chemotherapy revealed incidental papillary thyroid carcinoma as hypermetabolic thyroid foci. These incidental uptakes of ¹⁸F-FDG in the thyroid gland are rarely encountered in day-to-day practice of oncological PET/CT. However, they deserve an exploration to determine their etiology.     

Analyse texturale en TEP au FDG des cancers pulmonaires non à petites cellules de stade localement avancé : valeur pronostique de l’entropie

IntroductionIn the current context of personalized medicine, textural analysis promises to be an accurate approach of cancer prognosis. The lack of standardization and the multitude of textural indices limited radiomics studies reproducibility as an obstacle of introduction of textual analysis into clinical practice. Our study assessed the prognostic value of entropy in 18F-FDG PET/CT in locally advanced non-small cell lung cancer (NSCLC).MethodPatients who performed 18F-FDG PET/CT for lung cancer staging between September 2015 and April 2017 in 2 hospitals were included for conventional and textural PET parameters extraction. A retrospective analysis of patient was performed over 24 months to determine the progression-free survival and overall survival.ResultsForty-two patients were included. Progression-free survival was significantly correlated with entropy on multivariate regression (cut-off at 8.4) with a hazard ratio of 3.04 (95 % CI 1.13–8.16) (P = 0.03), as MTV (P < 0.001). Neither conventional PET parameters nor entropy was a significant association with overall survival.ConclusionThese results confirmed the external validity and robustness of FDG PET entropy as an independent prognostic factor of progression-free survival in patients with locally advanced NSCLC, in addition to Conventional PET.     

Comparaison IRM de diffusion corps entier et TEP/TDM au 18FDG dans le diagnostic de myélome symptomatique

IntroductionOur work aims to compare whole-body diffusion MRI (DWMRI) and ¹⁸FDG PET/CT in the diagnosis of symptomatic myeloma.Patients and methodFrom November 2008 till May 2010, 19 patients were investigated by DWMRI and by ¹⁸FDG PET/CT. The patients were classified according to the criteria of the International Myeloma Working Group in eight non-symptomatic myelomas and 11 symptomatic myelomas. The sensitivity and the specificity of two methods of imaging were studied by retaining the presence or the absence of a diffuse infiltration (ID), focal lesions (FL), or both parameters (FL + ID), in both modalities of imaging. We compared the concordance between two techniques for every patient by using these signs using a weighted kappa test.ResultsThe performances of both modalities seem comparable, with superior diagnostic performances for the FL (Se = 100% and Sp = 75% in DWMRI and Se = 91% and Sp = 75% for ¹⁸FDG PET/CT). By combining both parameters, the ¹⁸FDG PET/CT seems more specific, but the sensitivity is comparable in both modalities (Se = 100% in MRI and Se = 100% in ¹⁸FDG PET/CT; Sp = 37% in DWMRI and Sp = 62% for ¹⁸FDG PET/CT). The concordance between both techniques is better by taking into account the FL than the other parameters (weighted kappa = 0.61 for FL, 0.5 for the FL + ID and 0.16 for ID alone).ConclusionDiagnostic performances of whole-body diffusion MRI and ¹⁸FDG PET/CT seem equivalent, but concordance between both techniques is imperfect. Further studies are necessary to understand this discrepancy.     

Utilité de la TEP au 18FDG dans l’épilepsie. Méthodes et indications

Positron emission tomography (PET) using ¹⁸fluorodeoxyglucose (¹⁸FDG) is currently used in presurgical work-up for drug-resistant partial epilepsies in children as in adults, in addition to MRI. Recent cameras with less than 5 mm spatial resolution allow to obtain thin slices (about 2 mm thickness) in 3D planes. ¹⁸FDG is intravenously injected at the mean dose of 3 MBq/kg of body weight in interictal and resting state, in a quiet, dimly lit environment and careful monitoring for head movements and ictal events. In children, sedation may be necessary. Image acquisition starts 30 min after injection and ended 15 to 20 min later. Semiquantitative analysis is visually assessed in clinical practice using colour scales. PET sensibility is improved by superimposition of metabolic imaging on MRI. Statistical analysis with SPM may be useful but comparison with health subjects database is required. In medial temporal lobe epilepsy associated with hippocampal sclerosis, hypometabolism ipsilateral to the epileptogenic focus is found in 70 to 90% of the cases and is predictive of surgical outcome. In other types of temporal and extratemporal epilepsy with negative MRI, focal hypometabolism can be detected, allowing identification of minor gyral abnormalities corresponding to focal cortical dysplasias. In such MRI negative cases, PET findings may improve surgical outcome.