Comparaison de différents indices métaboliques et de la méthode SULTAN dans l’évaluation de la réponse thérapeutique par TEP au 18FDG dans le cancer du sein métastatique

Objective18F-FDG PET is a valuable tool in the evaluation of therapeutic response in breast cancer. This retrospective study was designed to compare the performance of six metabolic indices and to define their optimal thresholds, in patients treated with chemotherapy or hormone therapy for metastatic breast cancer. The performances of a parametric analysis by SULTAN method were also evaluated.MethodsTwenty patients, who underwent from 2 to 7 PET during the follow-up were analyzed. For each target, six indices were measured: SUVmax (maximum Standardized Uptake Value), SUVpeak, SAM (Standardized Added Metabolic activity), metabolic volume (MV), SUVmean using an adaptive threshold, and TLG (total lesion glycolysis). The percentage change of each target between each PET was calculated. A method based on parametric imaging (SULTAN) was also applied to each patient. The results were compared to the gold standard, defined by clinical evaluation, biological and morphological imaging RECIST 1.1 criteria. A per-lesion and per-patient analysis were performed and the optimal thresholds for each indices were calculated.ResultsFor the per-lesion analysis, 61 targets and 111 evolutions with 67 responders (R) and 44 non-responders (NR) were studied. Using ROC curve analysis and intercomparison, SUVmax, SUVpeak and SUVmean were significantly better than SAM, TLG and VM (P < 0.05). Using the optimal thresholds of −21%, –21%, –34%, –48% and –23% for SUVmax, SUVpeak, SUVmean, SAM and TLG respectively, these five indices were significantly correlated with the gold standard. SUVmax, SUVpeak and SUVmean showed the best performances of sensitivity (88%, 87% and 78% respectively), specificity (93%, 93% and 98% respectively) and negative predictive value (NPV) (84%, 69% and 74% respectively). For the per-patient analysis, 42 pairs of PET with 22 R and 20 NR were studied. Only SUVmax and SUVpeak were correlated to gold standard with the 30%-PERCIST-threshold and with optimal thresholds with performances of sensitivity of 73% and 77%, specificity of 95% and NPV of 76% and 79%. Parametric analysis with SULTAN showed excellent performances in the per-lesion and per-patient analysis (sensitivity 84% and 82%, specificity 98% and 90%, NPV 80% and 82%, respectively).ConclusionSUVmax and SUVpeak appeared the best indices to evaluate metabolic response in metastatic breast cancer. The SULTAN method was a reliable method to assist interpretation.     

Apport de la TEP/TDM au FDG en cancérologie de l’intestin grêle

This article focuses on the indication for FDG PET/CT in case of tumours of the small intestine, neuro-endocrine tumours excluded. The adenocarcinomas, lymphomas and sarcomas (including stromal tumours or GIST) are studied. There is no specific recommendation for FDG PET/CT in adenocarcinomas, extremely rare in comparison with colorectal adenocarcinomas. However, the utility of FDG PET/CT has been reported in clinical cases for detection and staging, especially in patients with high risk of developing the disease (Crohn's disease being the most important risk factor). The primary lymphomas of the small gut are also very rare, corresponding in all cases to non-Hodgkin lymphomas, for which the role of FDG PET/CT is recognised in follicular lymphoma, large B-cell lymphoma and Burkitt lymphoma. The stromal tumours correspond to the most frequent sarcomas. Stromal tumours in the small intestine are less frequent in the small intestine than in the stomach. The role of FDG PET/CT is well established in stromal tumours for the staging of the disease and for determining the efficacy of therapy with tyrosine kinase inhibitor. FDG PET is especially effective to evaluate the response since the radiologic criteria are difficult to assess, based not on the decrease of size of the lesions but on the decrease of density and of contrast enhance.     

Comparaison de l’IRM de diffusion et de la TEP/TDM au FDG dans le bilan des lymphomes

PurposeDiffusion weighted MRI (DW-MRI) sequences appear as a promising functional technique supplementary to morphologic MRI for oncology purposes. We evaluated the results of DW-MRI for the staging of lymphomas, compared to FDG PET/CT.MethodsTwenty-seven patients with lymphoma referred for FDG PET/CT (initial staging, relapse or treatment evaluation) were prospectively included. They underwent MRI including free breathing DW and T2 weighted imaging. Lymph node areas and organs involvement were listed for each modality and compared using Cohen's kappa (κ) test. MRI performances were evaluated using FDG PET as the gold standard. The results of PET and MRI were compared (with respect to the final staging by the haematologist).ResultsRegarding the lymph nodes, 154 involved areas were detected by MRI out of the 184 detected by PET, that is an excellent concordance (κ = 0.87), sensitivity of 0.84 and specificity of 1. Concordance and sensitivity were inferior for extranodal disease (notably bone lesions) with 27 lesions detected by MRI out of the 40 viewed with PET. Regarding pre-treatment evaluation, two patients were understaged both with PET and MRI (bone marrow involvement); assessment of stage was concordant for both modalities in 18 patients out of 21.ConclusionsPerformance of MRI including DW images was close to that of FDG PET/CT for lymph node areas involvement. Further studies are needed to assess its sensitivity for extranodal lesions, and its accuracy for determining the stage of the disease.     

Évaluation de la TEP au 18F-FDG dans l’exploration de la récidive des carcinomes colorectaux

PurposeThe aim of the study was to evaluate the diagnostic performance, the prognosis factors and the therapeutic impact of 18F-FDG positron emission tomography (FDG-PET) in the detection of recurrent colorectal cancers.MethodsSixty PET/CT with 18F-FDG and CT were performed in 52 patients, at the Paul Papin cancer center between 2003 and 2005, following suspicion of colorectal cancer relapse. The FDG-PET impact on the clinical management was studied by examination of multidisciplinary concertations results. Survival analysis were realized with a mean follow up of 2.2 years.ResultsRecurrence was confirmed for 50 explorations by histologic (n = 32), radiologic (n = 14) or clinical (n = 4) findings. Twenty patients died during the time of the study. On a patient based analysis, FDG-PET sensitivity, specificity and overall accuracy were 90, 90, 90% respectively compared with 74, 50 and 70% for CT. FDG-PET changed the clinical management in 18 cases (30%). A positive FDG-PET signal, more than one hepatic lesion, more than two lymph node lesions detected on FDG-PET and more than two hepatic lesions on CT were characterized as bad prognostic factors for survival. Multivariate analysis showed that the only independent bad prognostic factor was the FDG-PET detection of more than two liver lesions.ConclusionThese results confirmed the important impact of FDG-PET in the clinical management of patients with a suspected recurrence of colorectal cancer.     

Intérêt de la TEP au 18F-FDG préthérapeutique pour prédire la réponse à la radio-immunothérapie dans les lymphomes non hodgkiniens

PurposeRadioimmunotherapy (RIT) is a new treatment option for patients with non-Hodgkin lymphoma (NHL). Response to RIT currently remains difficult to predict using conventional prognostic factors and could be refined using functional imaging. The goal of this work is to evaluate the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting response to yttrium 90-labeled monoclonal antibodies for patients with NHL.MethodThirty-five patients with NHL who had undergone 18F-FDG PET prior to RIT with either 90Y-ibritumomab tiuxetan or 90Y-epratuzumab tetraxetan were included in this retrospective study. Four functional criteria (SUVmax, SUVmean, volume and the product of the volume and the SUVmean-TLG-) were analyzed on a per-lesion basis.ResultsA total of 154 lesions were analysed. The per-lesion analysis revealed significant differences (P < 0.05) between responders and non-responders for several criteria and above all for the SUV.ConclusionOur results suggest a predictive role of 18F-FDG PET prior to RIT by giving a useful indication of the radiosensitivity of the lymphoma.     

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.     

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.     

Apport de la TEP/TDM au 18FDG dans le bilan préopératoire des phéochromocytomes. Étude rétrospective comparative par rapport à la scintigraphie à la MIBG

Pheochromocytomas (PHEO) are tumors arisen from the adrenal medulla, with a high secretory risk. Malignancy is rare and difficult to establish before metastastic spread. The risk of multifocality becomes greater whether genetic predisposition exists. MIBG scintigraphy is the reference functional imaging of PHEO. The place of 18FDG PET/CT is not well-established in literature. Our study retrospectively analyzes patients operated for a PHEO and who underwent both MIBG and 18FDG PET/CT before surgery, between 2007 and 2015. On the 49 patients included (52 lesions), among them 13 had genetic mutation, MIBG detected 39 lesions (75%) and 18FDG PET/CT forty-eight (92%), enabling a combined sensitivity of 98%. Sensitivity was not affected by the predominant secretion (metanephrine or normetanephrine), whereas MIBG-negative lesions showed a higher proliferation index (Ki67) than MIBG-positive lesions (6.6 vs. 2.8; P = 0.0044). FDG PET/CT semi-quantitative indices vary with the germline mutation status and were significantly higher for Cluster 1 lesions (SDHx, VHL or FH mutations) than for any other lesions (SUVmax = 27.73 vs. 5.92 for the others mutations (Cluster 2), 9.53 for lesions without mutation and 3.78 for undetermined lesions; P = 0.002). In conclusion, because of their capacity to take up FDG, 18FDG PET/CT could be useful in the preoperative imaging of PHEO, especially when MIBG is not contributive or when F-DOPA PET/CT is not available. An intense FDG uptake may orient to a Cluster 1 mutation.     

Place de la TEP au 18FDG dans la localisation de primitifs néoplasiques

Carcinomas of unknown primary site (CUP) and paraneoplastic syndromes have the common characteristic that an extensive conventional biological and imaging analysis fails in some instance to detect the primary tumour. FDG-PET becomes recognized to provide interesting information in the case of “head and neck” CUP as well as in the case of neurological paraneoplastic syndromes biologically well defined. When, either CUP or paraneoplastic syndromes, are less defined, FDG-PET will not provide as much information as in the previous situation, although it can help in the etiologic diagnosis (oncologic or not) in some cases.     

Place de la TEP au FDG (18F) dans l’exploration des syndromes neurologiques paranéoplasiques

Paraneoplastic neurological syndromes (PNS) are rare non-metastatic manifestations of cancer. However, in this family of diseases, to recognize the underlying malignancy is an emergency. The ultimate aim is to treat the patient and try to stabilize or improve the neurological dysfunction, which is frequently the cause of the patient's death. The yield of FDG PET seems to be poor in unselected PNS. In the last decade, neurologists have attempted to provide more rigorous diagnostic criteria for PNS. Thus, “classical” PNS and a panel of “well-characterized” onconeural antibodies have been defined in order to facilitate triage of patients for whom FDG PET would be more sensitive. Currently, given the limited availability of PET cameras in France, this examination should be performed in the presence of either a “classical” PNS with or without onconeuralantibodies positivity or other PNS with onconeural antibodies positivity. The FDG PET should be triggered after a negative conventional imaging work up.     

Rôle de la TEP FDG dans l’évaluation de l’extension locorégionale et à distance du mélanome

FDG PET/CT is a relevant examination for patients with high-risk melanoma. For early stages with thickness ≥ 1 mm, lymph node ultrasound, and when negative, lymphoscintigraphy for determination of sentinel lymph node, remain necessary. For more advanced stages, FDG PET can map the lesions and guide the therapeutic strategy, either with surgical management, or systemic therapy (or sometimes both). In patients with high-risk melanoma, it allows to detect relapses early, including in asymptomatic patients, with a potential impact on therapeutic decisions. Beside the detection of classical secondary localizations, FDG PET has the advantage of allowing whole-body imaging, the identification of soft tissue lesions, frequent in melanomas, as well as rarer sites of involvement, such as those of the gastro-intestinal tract. For the assessment of cerebral and leptomeningeal involvement, MRI remains mandatory. Evolutions in the therapeutic management of advanced melanomas, and the search for biomarkers to guide the therapeutic strategy, ask for more refined analyses of PET, with metabolic tumour volume analysis and radiomics. The combination of metabolic imaging data with biological and molecular data, and the development of new PET tracers may improve the assessment of prognosis and the prediction of response to therapies, in order to tailor the therapeutic strategy to each patient. Further studies are needed to consolidate the role of PET/CT in this disease for which numerous therapeutic innovations are emerging.