Impact de la tomographie par émission de positons au 18F-Fluorodéoxyglucose dans la prise en charge des patients suivis pour mélanome malin (étude rétrospective de 82 cas au CHU de Brest)

BREST-BU Médecine-Odontologie (290192102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Intérêt de la scintigraphie au technétium 99 métastable ( 99m Tc) pour la prise en charge des ostéonécroses liées aux bisphosphonates

International audienc

Hotspot on 18F-FET PET/CT to Predict Aggressive Tumor Areas for Radiotherapy Dose Escalation Guiding in High-Grade Glioma

The standard therapy strategy for high-grade glioma (HGG) is based on the maximal surgery followed by radio-chemotherapy (RT-CT) with insufficient control of the disease. Recurrences are mainly localized in the radiation field, suggesting an interest in radiotherapy dose escalation to better control the disease locally. We aimed to identify a similarity between the areas of high uptake on O-(2-[18F]-fluoroethyl)-L-tyrosine (FET) positron emission tomography/computed tomography (PET) before RT-CT, the residual tumor on post-therapy NADIR magnetic resonance imaging (MRI) and the area of recurrence on MRI. This is an ancillary study from the IMAGG prospective trial assessing the interest of FET PET imaging in RT target volume definition of HGG. We included patients with diagnoses of HGG obtained by biopsy or tumor resection. These patients underwent FET PET and brain MRIs, both after diagnosis and before RT-CT. The follow-up consisted of sequential brain MRIs performed every 3 months until recurrence. Tumor delineation on the initial MRI 1 (GTV 1), post-RT-CT NADIR MRI 2 (GTV 2), and progression MRI 3 (GTV 3) were performed semi-automatically and manually adjusted by a neuroradiologist specialist in neuro-oncology. GTV 2 and GTV 3 were then co-registered on FET PET data. Tumor volumes on FET PET (MTV) were delineated using a tumor to background ratio (TBR) ≥ 1.6 and different % SUVmax PET thresholds. Spatial similarity between different volumes was performed using the dice (DICE), Jaccard (JSC), and overlap fraction (OV) indices and compared together in the biopsy or partial surgery group (G1) and the total or subtotal surgery group (G2). Another overlap index (OV’) was calculated to determine the threshold with the highest probability of being included in the residual volume after RT-CT on MRI 2 and in MRI 3 (called “hotspot”). A total of 23 patients were included, of whom 22% (n = 5) did not have a NADIR MRI 2 due to a disease progression diagnosed on the first post-RT-CT MRI evaluation. Among the 18 patients who underwent a NADIR MRI 2, the average residual tumor was approximately 71.6% of the GTV 1. A total of 22% of patients (5/23) showed an increase in GTV 2 without diagnosis of true progression by the multidisciplinary team (MDT). Spatial similarity between MTV and GTV 2 and between MTV and GTV 3 were higher using a TBR ≥ 1.6 threshold. These indices were significantly better in the G1 group than the G2 group. In the FET hotspot analysis, the best similarity (good agreement) with GTV 2 was found in the G1 group using a 90% SUVmax delineation method and showed a trend of statistical difference with those (poor agreement) in the G2 group (OV’ = 0.67 vs. 0.38, respectively, p = 0.068); whereas the best similarity (good agreement) with GTV 3 was found in the G1 group using a 80% SUVmax delineation method and was significantly higher than those (poor agreement) in the G2 group (OV’= 0.72 vs. 0.35, respectively, p = 0.014). These results showed modest spatial similarity indices between MTV, GTV 2, and GTV 3 of HGG. Nevertheless, the results were significantly improved in patients who underwent only biopsy or partial surgery. TBR ≥ 1.6 and 80–90% SUVmax FET delineation methods showing a good agreement in the hotspot concept for targeting standard dose and radiation boost. These findings need to be tested in a larger randomized prospective study

Hotspot on 18F-FET PET/CT to Predict Aggressive Tumor Areas for Radiotherapy Dose Escalation Guiding in High-Grade Glioma

The standard therapy strategy for high-grade glioma (HGG) is based on the maximal surgery followed by radio-chemotherapy (RT-CT) with insufficient control of the disease. Recurrences are mainly localized in the radiation field, suggesting an interest in radiotherapy dose escalation to better control the disease locally. We aimed to identify a similarity between the areas of high uptake on O-(2-[18F]-fluoroethyl)-L-tyrosine (FET) positron emission tomography/computed tomography (PET) before RT-CT, the residual tumor on post-therapy NADIR magnetic resonance imaging (MRI) and the area of recurrence on MRI. This is an ancillary study from the IMAGG prospective trial assessing the interest of FET PET imaging in RT target volume definition of HGG. We included patients with diagnoses of HGG obtained by biopsy or tumor resection. These patients underwent FET PET and brain MRIs, both after diagnosis and before RT-CT. The follow-up consisted of sequential brain MRIs performed every 3 months until recurrence. Tumor delineation on the initial MRI 1 (GTV 1), post-RT-CT NADIR MRI 2 (GTV 2), and progression MRI 3 (GTV 3) were performed semi-automatically and manually adjusted by a neuroradiologist specialist in neuro-oncology. GTV 2 and GTV 3 were then co-registered on FET PET data. Tumor volumes on FET PET (MTV) were delineated using a tumor to background ratio (TBR) ≥ 1.6 and different % SUVmax PET thresholds. Spatial similarity between different volumes was performed using the dice (DICE), Jaccard (JSC), and overlap fraction (OV) indices and compared together in the biopsy or partial surgery group (G1) and the total or subtotal surgery group (G2). Another overlap index (OV’) was calculated to determine the threshold with the highest probability of being included in the residual volume after RT-CT on MRI 2 and in MRI 3 (called “hotspot”). A total of 23 patients were included, of whom 22% (n = 5) did not have a NADIR MRI 2 due to a disease progression diagnosed on the first post-RT-CT MRI evaluation. Among the 18 patients who underwent a NADIR MRI 2, the average residual tumor was approximately 71.6% of the GTV 1. A total of 22% of patients (5/23) showed an increase in GTV 2 without diagnosis of true progression by the multidisciplinary team (MDT). Spatial similarity between MTV and GTV 2 and between MTV and GTV 3 were higher using a TBR ≥ 1.6 threshold. These indices were significantly better in the G1 group than the G2 group. In the FET hotspot analysis, the best similarity (good agreement) with GTV 2 was found in the G1 group using a 90% SUVmax delineation method and showed a trend of statistical difference with those (poor agreement) in the G2 group (OV’ = 0.67 vs. 0.38, respectively, p = 0.068); whereas the best similarity (good agreement) with GTV 3 was found in the G1 group using a 80% SUVmax delineation method and was significantly higher than those (poor agreement) in the G2 group (OV’= 0.72 vs. 0.35, respectively, p = 0.014). These results showed modest spatial similarity indices between MTV, GTV 2, and GTV 3 of HGG. Nevertheless, the results were significantly improved in patients who underwent only biopsy or partial surgery. TBR ≥ 1.6 and 80–90% SUVmax FET delineation methods showing a good agreement in the hotspot concept for targeting standard dose and radiation boost. These findings need to be tested in a larger randomized prospective study

Feasibility of Systematic Respiratory-Gated Acquisition in Unselected Patients Referred for 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

ObjectiveRespiratory motion in 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) induces blurred images, leading to errors in location and quantification for lung and abdominal lesions. Various methods have been developed to correct for these artifacts, and most of current PET/CT scanners are equipped with a respiratory gating system. However, they are not routinely performed because their use is time-consuming. The aim of this study is to assess the feasibility and quantitative impact of a systematic respiratory-gated acquisition in unselected patients referred for FDG PET/CT, without increasing acquisition time.MethodsPatients referred for a FDG PET/CT examination to the nuclear medicine department of Brest University Hospital were consecutively enrolled, during a 3-month period. Cases presenting lung or liver uptakes were analyzed. Two sets of images were reconstructed from data recorded during a unique acquisition with a continuous table speed of 1 mm/s of the used Biograph mCT Flow PET/CT scanner: standard free-breathing images, and respiratory-gated images. Lesion location and quantitative parameters were recorded and compared.ResultsFrom October 1 2015 to December 31 2015, 847 patients were referred for FDG PET/CT, 741 underwent a respiratory-gated acquisition. Out of them, 213 (29%) had one or more lung or liver uptake but 82 (38%) had no usable respiratory-gated signal. Accordingly, 131 (62%) patients with 183 lung or liver uptakes were analyzed. Considering the 183 lesions, 140 and 43 were located in the lungs and the liver, respectively. The median (IQR) difference between respiratory-gated images and non-gated images was 18% (4−32) for SUVmax, increasing to 30% (14−57) in lower lobes for lung lesions, and −18% (−40 to −4) for MTV (p < 0.05). Technologists’ active personal dosimetry and mean total examinations duration were not statistically different between periods with and without respiratory gating.ConclusionThis study showed that a systematic respiratory-gated acquisition without increasing acquisition time is feasible in a daily routine and results in a significant impact on PET quantification. However, clinical impact on patient management remains to be determined

Identification of patients with indolent B cell lymphoma sensitive to rituximab monotherapy.

International audienceThe potential predictive value of tumor bulk, genetic, and immunological variants in patients with low-grade non-Hodgkin's lymphoma to respond to treatment with rituximab (RTX) monotherapy was evaluated. Thus, the value of assessing the effect of 18-fluoro-desoxy-D-glucose (FDG) uptake on PET scan, polymorphisms in Fc gamma receptor (FcγR) IIIa-158, FcγRIIa-131, and C1qA-276 genes in predicting the response to treatment were evaluated in 50 low-grade non-Hodgkin's lymphoma patients. The influence of RTX pharmacokinetics, plasma levels of the B cell-activating factor (BAFF), and human antichimeric antibodies was also investigated. The therapeutic response was evaluated 10 weeks after treatment using revised Cheson's criteria. Lower maximal standardized uptake values (SUV(max)) at baseline were predictive of complete response. FcγRIIIa-158 polymorphism was also associated with complete response to RTX confirming previous findings, whereas polymorphisms in the FcγRIIa-131 and C1qA-276 genes were not. Lower blood levels of RTX were observed in males, but the effectiveness of RTX in males and females was the same. BAFF was not detectable in plasma before or after treatment, and no patients developed human antichimeric antibodies. Low-grade non-Hodgkin's lymphoma patients with a low SUV(max) at baseline and an FcγRIIIa-158 V/V genotype generally had a complete response to RTX

Prognostic value of dual-time-point 18F-FDG PET-CT imaging in patients with head and neck squamous cell carcinoma.

International audienceOBJECTIVE: The objective of this study was to investigate the independent prognostic value of dual-time-point F-fluorodeoxyglucose (F-FDG) PET-CT imaging in patients with head and neck squamous cell carcinoma (HNSCC). METHODS: Patients referred to our department to undergo F-FDG PET-CT for staging of HNSCC were prospectively included. Each patient was scanned using a Philips Gemini PET-CT system 1 h (early acquisition) and 2 h (delayed acquisition) after injection. An intratumoral retention index (RI) of F-FDG was measured for each examination by the dual-time-point method. Event-free survival (EFS) and overall survival (OS) were determined by the Kaplan-Meier method and compared with the conventional maximum standardized uptake value (SUVmax) at 60 min, SUVmax at 120 min, and RI in univariate and multivariate analyses including the usual prognostic factors such as age, sex, primary site, SCC histologic grade, and American Joint Committee on Cancer stage (I, II, III, and IV). RESULTS: Sixty-six consecutive patients (60 men and six women; mean age=61±9 years) were included in the study. In univariate analysis, besides age and stage, RI was predictive of EFS (P=0.01) but not of OS (P=0.1), whereas SUVmax at 60 min was not predictive of EFS (P=0.18) or OS (P=0.08) and SUVmax at 120 min was predictive of OS (P=0.02) but not of EFS (P=0.05). In multivariate analysis, RI persisted as an independent predictive factor for EFS (P=0.02) but not SUVmax at 120 min for OS (P=0.12). CONCLUSION: Our results suggest an additional prognostic interest of RI measured by dual-time-point F-FDG PET-CT, independent of usual prognostic factors, in patients with HNSCC

Comparison of F-18-Choline PET/CT and MRI functional parameters in prostate cancer

International audienc

Diagnosis of pulmonary embolism: planar images generated from V/Q SPECT are not a reliable substitute for traditional planar V/Q scan.

International audienceOBJECTIVES: The use of summed planar images generated from single-photon emission computed tomography (SPECT) ventilation/perfusion (V/Q) scintigraphy has been proposed as a substitute for planar V/Q scans in order to use the revised PIOPED interpretation criteria when only SPECT acquisition is performed in patients with suspected pulmonary embolism. The aim was to evaluate the accuracy of angular summed planar scans in comparison with true planar images. METHODS: Patients included in the 'SPECT study' assessing the diagnostic performance of V/Q SPECT were analysed. Angular summed planar images were generated from SPECT acquisition data and compared with true planar scans. RESULTS: Angular summed planar images were successfully generated for 246 patients. Regarding interobserver variability, the interpretation result was different for 15 (6%) summed planar scans with an excellent degree of agreement (κ=0.92; 95% confidence interval 0.88-0.96). With regard to intermodality interpretation variability between conventional planar and angular summed images, the result was different for 63 (26%) of 246 patients with an intermodality degree of agreement of κ=0.66 (95% confidence interval 0.58-0.73). CONCLUSION: Planar images generated from SPECT V/Q scintigraphy are not a reliable substitute for true planar V/Q images

Comparison of choline influx from dynamic F-Choline PET/CT and clinicopathological parameters in prostate cancer initial assessment

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