Interest of pet imaging in multiple myeloma

The interest of 18Fluoro-deoxyglucose (FDG) positron emission tomography (PET) imaging in the management of patients with multiple myeloma (MM) for the workup at diagnosis and for therapeutic evaluation has recently been demonstrated. FDG-PET is a powerful imaging tool for bone lesions detection at initial diagnosis with high sensitivity and specificity values. The independent pejorative prognostic value on progression-free survival (PFS) and overall survival (OS) of baseline PET-derived parameters (presence of extra-medullary disease (EMD), number of focal bone lesions (FLs), and maximum standardized uptake values [SUVmax]) has been reported in several large independent prospective studies. During therapeutic evaluation, FDG-PET is considered as the reference imaging technique, because it can be performed much earlier than MRI which lacks specificity. Persistence of significant FDG uptake after treatment, notably before maintenance therapy, is an independent pejorative prognostic factor, especially for patients with a complete biological response. So FDG-PET and medullary flow cytometry are complementary tools for detection of minimal residual disease before maintenance therapy. However, the definition of PET metabolic complete response should be standardized. In patients with smoldering multiple myeloma, the presence of at least one hyper-metabolic lytic lesions on FDG-PET may be considered as a criterion for initiating therapy. FDG-PET is also indicated for initial staging of a solitary plasmacytoma so as to not disregard other bone or extra-medullary localizations. Development of nuclear medicine offer new perspectives for MM imaging. Recent PET tracers are willing to overcome limitations of FDG. (11)C-Methionine, which uptake reflects the increased protein synthesis of malignant cells seems to correlate well with bone marrow infiltration. Lipid tracers, such as Choline or acetate, and some peptide tracers, such as (68) Ga-Pentixafor, that targets CXCR4 (chemokine receptor-4, which is often expressed with high density by myeloma cells), are other promising PET ligands. 18F-fludarabine and immuno-PET targeting CD138 and CD38 also showed promising results in preclinical models

Obinutuzumab versus Rituximab in young patients with advanced DLBCL, a PET-guided and randomized phase 3 study by LYSA.

Rituximab plus polychemotherapy is standard of care in diffuse large B-cell lymphoma (DLBCL). GAINED trial compares obinutuzumab to rituximab. GAINED (NCT01659099) is an open-label, randomized phase 3 trial. Transplant-eligible patients (18-60yrs) with untreated aged-adjusted international prognostic index (aaIPI) ≥1 DLBCL were randomized (1:1) between obinutuzumab or rituximab. Patients were stratified by aaIPI (1; 2-3) and chemotherapy regimen (ACVBP; CHOP). Consolidation treatment was determined according to response assessed by centrally reviewed interim semi-quantitative PET. Responders after cycle 2 and 4 (PET2-/PET4-) received planned immuno-chemotherapy consolidation. Responders only after cycle 4 (PET2+/4-) received highdose methotrexate plus transplantation. The primary objective was an 8% improvement (HR=0.73; 80% power; alpha risk 2.5%; one-sided) in 2-year event-free survival (EFS) in the obinutuzumab arm. Events included death, progression, PET 2 or 4 positivity, modification of planned treatment. From September 20, 2012, 670 patients were enrolled (obinutuzumab n=336; rituximab n=334). 383 (57.2%) were aaIPI 2-3, 339 (50.6%) received CHOP and 324 (48.4%) received ACVBP. Median follow-up was 38.7 months. The 2-year EFS were similar in obinutuzumab and rituximab groups (59.8% vs 56.6%; p=0.123; HR=0.88). The 2-year PFS in the whole cohort was 83.1% (95%CI 80–85.8). PET2-/4- and PET2+/4- had similar 2-year PFS and OS (89.9% vs 83.9%) and 94.8% vs 92.8%). The 2-year PFS and OS for PET4+ patients were 62% and 83.1%. Grade 3-5 infections were more frequent in the obinutuzumab arm (21% vs 12%). Obinutuzumab is not superior to rituximab in untreated aaIPI≥1 DLBCL transplant-eligible patients

Fluorinated tracers for imaging tumoral proliferation with positron emission tomography

peer reviewedLe 18F-fluorodeoxyglucose (FDG) est actuellement le seul traceur fluoré utilisé en routine en tomographie par émission de positons (TEP). Le fluor 18 peut être considéré comme le radioisotope TEP idéal avec : 1) une émission positonique de faible énergie (0,64 MeV), limitant l'irradiation reçue par le patient ainsi que le parcours du positon dans les tissus (2,3 mm), avec comme conséquence directe, une haute résolution des images TEP; 2) une période de 110 minutes permettant une radiosynthèse avec un bon rendement, un transport depuis l'établissement de radiopharmacie vers des services de médecine nucléaire distants, et des protocoles d'imagerie pouvant s'étendre sur quelques heures, ce qui facilite les études dynamiques et de processus métaboliques relativement lents. Récemment, la radiosynthèse fluorée à partir de groupes prothétiques précurseurs, qui permet le marquage de molécules bioactives dans de bonnes conditions, a donné un nouvel élan au développement de nombreux traceurs fluorés. En raison de la disponibilité du fluor, ils pourraient occuper dans un avenir proche une place importante en routine. Cet article et une revue de la littérature concernant les traceurs fluorés récemment développés et/ou en cours d'investigation, susceptibles d'être employés pour évaluer la prolifération tumorale

Predictive value of FDG‐PET imaging for relapse in metastatic melanoma patients treated with immunotherapy

International audienceBackground: Anti-PD1 immunotherapy has shown a sustainable clinical activity in patients with metastatic melanoma. However, strong predictive factors of the long-term response or risk of relapse remain to be identified.Objectives: To determine whether FDG-PET imaging could be superior to CT scan in distinguishing residual tumours versus the absence of tumour in patients with a partial response (PR) or stable disease (SD) and whether a complete metabolic response (CMR) was associated with better outcomes.Methods: Retrospective study conducted in all patients with metastatic melanoma treated with anti-PD1 immunotherapy between October 2014 and October 2017 considered to be in complete remission. The primary outcome was the occurrence of a relapse during the follow-up. CT scan and FDG-PET scan had to be performed within a maximum of 2 months of treatment discontinuation. For CT imaging, the Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 were used and included progressive disease (PD), SD, PR and complete response (CR). For FDG-PET imaging, the metabolic responses were classified as progressive metabolic disease, stable metabolic disease, residual FDG avidity (RFA) and CMR.Results: Twenty-six patients were in complete remission after collegial decision. Two patients had a SD on CT scan and a CMR on FDG-PET scan, and none of them relapsed. Ten patients had a PR on CT scan and a CMR on FDG-PET scan, and none of them relapsed. The mean treatment duration to achieve a complete remission was 7 months (3-23). A univariate analysis showed that a RFA assessed on the FDG-PET scan was significantly associated with a relapse (P = 0.00231).Conclusions: Most patients with a PR on the CT scan and a CMR on the FDG-PET scan should be considered with a CR. Our study showed that FDG-PET imaging could play a crucial role in predicting the long-term outcome and help to decide whether treatment should be discontinued

Tomographie pinhole au MIBI-Tc99m dans l’hyperparathyroïdie primaire: comparaison des reconstructions iterative et analytique.

peer reviewe

FDG-PET in Follicular Lymphoma Management

18-Fluoro-deoxyglucose positron emission tomography/computerised tomography (FDG PET/CT) is commonly used in the management of patients with lymphomas and is recommended for both initial staging and response assessment after treatment in patients with diffuse large B-cell lymphoma and Hodgkin lymphoma. Despite the FDG avidity of follicular lymphoma (FL), FDG PET/CT is not yet applied in standard clinical practice for patients with FL. However, FDG PET/CT is more accurate than conventional imaging for initial staging, often prompting significant management change, and allows noninvasive characterization to guide assessment of high-grade transformation. For restaging, FDG PET/CT assists in distinguishing between scar tissue and viable tumors in residual masses and a positive PET after induction treatment would seem to predict a shorter progression-free survival

Maladie de Rosai-Dorfman-Destombes (RDD) multifocale réfractaire associée à un syndrome myélodysplasique. Efficacité du traitement hématologique

International audienc

Intérêt pronostique et prédictif de la TEP-TDM au 18F-FDG au bilan initial des mélanomes de stade IIIB-C-D et IV avant traitement par anti-PD-1

International audiencePurposeThe advent of immunotherapy by checkpoint inhibitor has profoundly changed the prognosis of patients with metastatic melanoma. The objective of our study was to evaluate the prognostic and predictive performance of 18F-FDG PET/CT of the initial extension assessment of stage IIIB-C-D and IV melanomas.MethodsWe retrospectively included 57 patients who had 18F-FDG PET/CT prior to the introduction of anti-PD-1 immunotherapy. The parameters extracted were SUVmax, SUV peak, MTV and TLG of the lesion with highest uptake (MTV LM, TLG LM), as well as MTV total and TLG total, obtained by adaptive segmentation. The18F-FDG PET/CT were dichotomized using the optimal threshold measured according to the area under the curve in the ROC (Receiver Operation Characteristic) curves. These parameters were evaluated using a Cox model. Overall survival and progression-free survival analyses were performed using the Kaplan Meier model.ResultsThe median follow-up was 25.4 months, 38 patients had progressed or recurred, and 20 patients had died. TLG LM>132.59 (P=0.0011), MTV total>12 cm3 (P=0.0139), and TLG>94.17 (P=0.0084) were significantly associated with a shorter progression-free survival. TLG LM>145.92 (P=0.0062), MTV total>10.16 cm3 (P=0.0051), and a metastatic spread>2 organs (P=0.0001) were associated with a shorter overall survival.ConclusionWe confirm the potential prognostic interest of PET-TDM at 18FDG before immunotherapy of stage IIIB-C-D and IV melanomas on progression-free survival and overall survival. The combination of these metabolic markers reflecting tumor burden with clinical and biological prognostic factors could allow early identification of patients at high risk of anti-PD-1 failure.IntroductionL’avènement des immunothérapies par inhibition des points de contrôle a profondément modifié le pronostic des patients atteints de mélanomes métastatiques. L’objectif de notre étude était d’évaluer les performances pronostiques de la TEP-TDM au 18FDG du bilan d’extension initial des mélanomes de stade IIIB-C-D et IV.Matériel et méthodesNous avons inclus rétrospectivement 57 patients ayant bénéficié d’une TEP-TDM au 18FDG avant introduction d’une immunothérapie par anti-PD-1. Les paramètres extraits étaient la SUV max, la SUV peak, le MTV et le TLG de la lésion la plus fixante (MTV LM, TLG LM), ainsi que le MTV et le TLG total, obtenus par segmentation adaptative. Les paramètres TEP-TDM au 18FDG ont été dichotomisés en utilisant le seuil optimal mesuré selon l’aire sous la courbe dans les courbes ROC (Receiver Operation Characteristic). Ces paramètres ont été évalués à l’aide d’un modèle de Cox. Les analyses de survie globale et sans progression ont été réalisées à l’aide du modèle de Kaplan Meier.RésultatLe suivi médian était de 25,4 mois, 38 patients avaient progressé ou récidivé, parmi lesquels 20 étaient décédés. Un TLG LM>132,59 (p=0,0011), un MTV total>12 cm3 (p=0,0139) et un TLG total>94,17 (p=0,0084) étaient significativement associés à une survie sans progression moins longue. Un TLG LM>145,92 (p=0,0062), un MTV total>10,16 cm3 (p=0,0051) et une dissémination métastatique>2 organes (p=0,0001) étaient associés à une survie globale plus courte.DiscussionNous confirmons l’intérêt pronostique potentiel de la TEP-TDM au 18FDG avant immunothérapie des mélanomes de stade IIIB-C-D et IV sur la survie sans progression et la survie globale. La combinaison de ces marqueurs métaboliques reflétant la charge tumorale à des facteurs pronostiques clinicobiologiques pourrait permettre d’identifier précocement les patients à haut risque d’échec des anti-PD-1