False Positive 18F-FDG Positron Emission Tomography Findings in Schwannoma—A Caution for Reporting Physicians

Schwannoma is a rare source of false-positive 18F-fluorodeoxyglucose (18F-FDG) uptake in Positron-emission tomography (PET/CT), inducing potential errors in staging of several solid cancer, with implications for patient management. This clinical case reports the situation of a patient undergoing an 18F-FDG-PET/CT for initial staging of an ovarian adenocarcinoma. We found a high paramediastinal hypermetabolic mass suspicious of remote extension or secondary synchronous primitive tumor. The biopsy finally reveals a histopathology of Schwannoma, allowing the patient to be eligible for a surgical procedure of her ovarian adenocarcinoma by rejecting the hypothesis of malignancy

HLA-DR expression in melanoma: from misleading therapeutic target to potential immunotherapy biomarker

Since the advent of anti-PD1 immune checkpoint inhibitor (ICI) immunotherapy, cutaneous melanoma has undergone a true revolution with prolonged survival, as available 5-year updates for progression-free survival and overall survival demonstrate a durable clinical benefit for melanoma patients receiving ICI. However, almost half of patients fail to respond to treatment, or relapse sooner or later after the initial response to therapy. Little is known about the reasons for these failures. The identification of biomarkers seems necessary to better understand this resistance. Among these biomarkers, HLA-DR, a component of MHC II and abnormally expressed in certain tumor types including melanoma for unknown reasons, seems to be an interesting marker. The aim of this review, prepared by an interdisciplinary group of experts, is to take stock of the current literature on the potential interest of HLA-DR expression in melanoma as a predictive biomarker of ICI outcome

Prognostic Value of Whole-Body PET Volumetric Parameters Extracted from 68Ga-DOTATOC PET/CT in Well-Differentiated Neuroendocrine Tumors

Our objective was to evaluate the prognostic value of somatostatin receptor tumor burden on Ga-68-DOTATOC PET/CT in patients with well-differentiated (WD) neuroendocrine tumors (NETs). Methods: We retrospectively analyzed the 68Ga-DOTATOC PET/CT scans of 84 patients with histologically confirmed WD NETs (51 grade 1, 30 grade 2, and 3 grade 3). For each PET/CT scan, all Ga-68-DOTATO-Cavid lesions were independently segmented by 2 operators using a customized threshold based on the healthy liver SUVmax (LIFEx, version 5.1). Somatostatin receptor-expressing tumor volume (SRETV) and total lesion somatostatin receptor expression (TLSRE = SRETV X SUVmean) were extracted for each lesion, and then whole-body SRETV and TLSRE (SRETVwb and TLSREwb, respectively) were defined as the sum of SRETV and TLSRE, respectively, for all segmented lesions in each patient. Time to progression (TTP) was defined as the combination of disease-free survival in patients undergoing curative surgery (n = 10) and progression-free survival for patients with unresectable or metastatic disease (n = 74). TTP and overall survival were calculated by Kaplan-Meier analysis, log-rank testing, and the Cox proportional-hazards regression model. Results: After a median follow-up of 15.5 mo, disease progression was confirmed in 35 patients (41.7%) and 14 patients died. A higher SRETVwb (>39.1 cm(3)) and TLSREwb (>306.8 g) correlated significantly with a shortermedian TTP (12 mo vs. not reached; P < 0.001). In multivariate analysis, SRETVwb (P = 0.005) was the only independent predictor of TTP regardless of histopathologic grade and TNM staging. Conclusion: According to our results, SRETVwb and TLSREwb extracted from Ga-68-DOTATOC PET/CT could predict TTP or overall survival and might have important clinical utility in the management of patients with WD NETs

Diagnostic Value of FDG PET-CT Quantitative Parameters and Deauville-Like 5 Point-Scale in Predicting Malignancy of Focal Thyroid Incidentaloma

Objective: To evaluate the diagnostic value of FDG PET-CT metabolic parameters and Deauville-like 5 point-scale to predict malignancy in a population of patients presenting focal thyroid incidentaloma (fTI).Design: This retrospective study included 41 fTI, classified according to cytological and histological data as benign (BL) or malignant lesion (ML). FDG PET-CT semi-quantitative parameters (SUVmax, SUVmean, SUVpeak, MTV, TLG), tumor to liver SUVmean ratio (TLRmax and TLRmean), tumor to blood-pool SUVmean ratio (TBRmax and TBRmean) were calculated. Each fTI was also classified on a Deauville-like 5-point scale (DS) currently used in lymphoma. Comparison between BL and ML was performed for each parameter and a ROC analysis was conducted.Results: All quantitative PET metabolic parameters (SUV parameters, volume based parameters and SUV ratio) were higher in ML compared with BL, yet no significant difference was reported. fTI (uptake) malignancy rate according to DS grades 2, 3, 4, and 5 was, respectively, 25% (1 of 4), 28.6% (2 of 7), 8.3% (1 of 12), and 33.3% (6 of 18) with no significant difference between ML and BL groups. Results of ROC analysis showed that mean TBR had the highest AUC in our cohort (0.66 95%CI [0.41; 0.91]) with a cut-off value of 2.2. Specificity of MTV and TLG was 100% (cut-off values: MTV 9.6 ml, TLG 22.9 g) and their sensitivity was 30 and 40%, respectively.Conclusion: Our study did not highlight any FDG PET/CT parameter predictor of fTI malignancy

Hybrid PET- and MR-driven attenuation correction for enhanced ¹⁸F-NaF and ¹⁸F-FDG quantification in cardiovascular PET/MR imaging

Background: The standard MR Dixon-based attenuation correction (AC) method in positron emission tomography/magnetic resonance (PET/MR) imaging segments only the air, lung, fat and soft-tissues (4-class), thus neglecting the highly attenuating bone tissues and affecting quantification in bones and adjacent vessels. We sought to address this limitation by utilizing the distinctively high bone uptake rate constant Ki expected from ¹⁸F-Sodium Fluoride (¹⁸F-NaF) to segment bones from PET data and support 5-class hybrid PET/MR-driven AC for ¹⁸F-NaF and ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) PET/MR cardiovascular imaging. Methods: We introduce 5-class Ki/MR-AC for (i) ¹⁸F-NaF studies where the bones are segmented from Patlak Ki images and added as the 5th tissue class to the MR Dixon 4-class AC map. Furthermore, we propose two alternative dual-tracer protocols to permit 5-class Ki/MR-AC for (ii) ¹⁸F-FDG-only data, with a streamlined simultaneous administration of ¹⁸F-FDG and ¹⁸F-NaF at 4:1 ratio (R4:1), or (iii) for ¹⁸F-FDG-only or both ¹⁸F-FDG and ¹⁸F-NaF dual-tracer data, by administering ¹⁸F-NaF 90 minutes after an equal ¹⁸F-FDG dosage (R1:1). The Ki-driven bone segmentation was validated against computed tomography (CT)-based segmentation in rabbits, followed by PET/MR validation on 108 vertebral bone and carotid wall regions in 16 human volunteers with and without prior indication of carotid atherosclerosis disease (CAD). Results: In rabbits, we observed similar (< 1.2% mean difference) vertebral bone ¹⁸F-NaF SUVmean scores when applying 5-class AC with Ki-segmented bone (5-class Ki/CT-AC) vs CT-segmented bone (5-class CT-AC) tissue. Considering the PET data corrected with continuous CT-AC maps as gold-standard, the percentage SUVmean bias was reduced by 17.6% (¹⁸F-NaF) and 15.4% (R4:1) with 5-class Ki/CT-AC vs 4-class CT-AC. In humans without prior CAD indication, we reported 17.7% and 20% higher ¹⁸F-NaF target-to-background ratio (TBR) at carotid bifurcations wall and vertebral bones, respectively, with 5- vs 4-class AC. In the R4:1 human cohort, the mean ¹⁸F-FDG:¹⁸F-NaF TBR increased by 12.2% at carotid bifurcations wall and 19.9% at vertebral bones. For the R1:1 cohort of subjects without CAD indication, mean TBR increased by 15.3% (¹⁸F-FDG) and 15.5% (¹⁸F-NaF) at carotid bifurcations and 21.6% (¹⁸F-FDG) and 22.5% (¹⁸F-NaF) at vertebral bones. Similar TBR enhancements were observed when applying the proposed AC method to human subjects with prior CAD indication. Conclusions: Ki-driven bone segmentation and 5-class hybrid PET/MR-driven AC is feasible and can significantly enhance ¹⁸F-NaF and ¹⁸F-FDG contrast and quantification in bone tissues and carotid walls

18F-fluorodesoxyglucose positon emission tomography for head and neck squamous cell carcinoma refractory to treatment

Nous avons initialement réalisé une étude prospective évaluant l’intérêt de la TEP-TDM au FDG pour le diagnostic de récidive infra-clinique des carcinomes épidermoïdes des voies aéro-digestives supérieures. Nos résultats ont montré d’excellentes performances de l’examen en surveillance systématique, permettant notamment le diagnostic de récidive chez environ 1/3 des patients cliniquement asymptomatiques 1 an après la fin du traitement. Nous avons ensuite étudié le bénéfice d’une évaluation thérapeutique précoce par TEP-TDM au FDG à 2 cures d’une chimiothérapie néoadjuvante par TPF précédant une radiochimiothérapie sur une cohorte de sujets porteurs d’un cancer localement avancé (stade IIIIVA). Nos résultats ont montré une corrélation statistiquement significative entre la réponse métabolique et la survie sans récidive, suggérant l’intérêt d’un examen intermédiaire pour cibler de façon précoce les patients réfractaires au traitement. Nous avons ensuite analysé prospectivement l’impact pronostique de la TEP-TDM au FDG réalisée en situation préthérapeutique dans le but de sélectionner encore plus précocement cette population à risque de récidive. Les résultats de nos 2 études ont prouvé que l’utilisation de paramètres volumétriques ou cinétiques de la captation intra-tumorale du FDG était prédictive de la survie globale, avec une valeur pronostique indépendante et supérieure à celle du SUVmax. Cette thèse ouvre ainsi des perspectives de nouvelles indications de la TEP-TDM au FDG dans la prise en charge des carcinomes épidermoïdes des VADS, soulève des problématiques de recherche avec notamment l’émergence des nouveaux traceurs permettant de caractériser au mieux la cellule tumorale et s’inscrit dans une volonté actuelle d’une médecine préventive et prédictive personnalisée.We initially conducted a prospective study evaluating diagnostic interest of FDG PET-CT for head and neck squamous cell carcinomas subclinical recurrence. Our results showed FDG PET-CT high performance in systematic monitoring, especially for the diagnosis of recurrence in about one third of clinically asymptomatic patients 1 year after the end of treatment. Secondly, we studied the benefits of early treatment evaluation by FDG PET-CT after 2 cycles of neoadjuvant chemotherapy by DCF (docetaxel, cysplatin, 5-fluorouracil) before chemoradiotherapy in a cohort of patients with locally advanced cancer (stage III-IVA). Our results showed a statistically significant correlation between metabolic tumor response and recurrence-free survival, suggesting the interest of an interim PETscan to early target patients refractory to treatment. Then, we prospectively analyzed the prognostic impact of FDG PET-CT performed at initial staging in order to select earlier this population at risk for recurrence. The results of our two studies proved that the use of volumetric or kinetic parameters of intratumoral FDG uptake was predictive of overall survival, with an independent prognostic value and a higher performance to SUVmax. Thus, this thesis opens new perspectives indications of FDG PET-CT in the management of head and neck squamous cell carcinoma, raises research issues such as the emergence of new tracers to characterize at best the tumor cell and falls within a current commitment to move towards a personalized preventive and predictive medicine

Tomographie par émission de positons au 18F-fluorodesoxyglucose et carcinome épidermoïde des voies aérodigestives supérieures réfractaire au traitement

We initially conducted a prospective study evaluating diagnostic interest of FDG PET-CT for head and neck squamous cell carcinomas subclinical recurrence. Our results showed FDG PET-CT high performance in systematic monitoring, especially for the diagnosis of recurrence in about one third of clinically asymptomatic patients 1 year after the end of treatment. Secondly, we studied the benefits of early treatment evaluation by FDG PET-CT after 2 cycles of neoadjuvant chemotherapy by DCF (docetaxel, cysplatin, 5-fluorouracil) before chemoradiotherapy in a cohort of patients with locally advanced cancer (stage III-IVA). Our results showed a statistically significant correlation between metabolic tumor response and recurrence-free survival, suggesting the interest of an interim PETscan to early target patients refractory to treatment. Then, we prospectively analyzed the prognostic impact of FDG PET-CT performed at initial staging in order to select earlier this population at risk for recurrence. The results of our two studies proved that the use of volumetric or kinetic parameters of intratumoral FDG uptake was predictive of overall survival, with an independent prognostic value and a higher performance to SUVmax. Thus, this thesis opens new perspectives indications of FDG PET-CT in the management of head and neck squamous cell carcinoma, raises research issues such as the emergence of new tracers to characterize at best the tumor cell and falls within a current commitment to move towards a personalized preventive and predictive medicine.Nous avons initialement réalisé une étude prospective évaluant l’intérêt de la TEP-TDM au FDG pour le diagnostic de récidive infra-clinique des carcinomes épidermoïdes des voies aéro-digestives supérieures. Nos résultats ont montré d’excellentes performances de l’examen en surveillance systématique, permettant notamment le diagnostic de récidive chez environ 1/3 des patients cliniquement asymptomatiques 1 an après la fin du traitement. Nous avons ensuite étudié le bénéfice d’une évaluation thérapeutique précoce par TEP-TDM au FDG à 2 cures d’une chimiothérapie néoadjuvante par TPF précédant une radiochimiothérapie sur une cohorte de sujets porteurs d’un cancer localement avancé (stade IIIIVA). Nos résultats ont montré une corrélation statistiquement significative entre la réponse métabolique et la survie sans récidive, suggérant l’intérêt d’un examen intermédiaire pour cibler de façon précoce les patients réfractaires au traitement. Nous avons ensuite analysé prospectivement l’impact pronostique de la TEP-TDM au FDG réalisée en situation préthérapeutique dans le but de sélectionner encore plus précocement cette population à risque de récidive. Les résultats de nos 2 études ont prouvé que l’utilisation de paramètres volumétriques ou cinétiques de la captation intra-tumorale du FDG était prédictive de la survie globale, avec une valeur pronostique indépendante et supérieure à celle du SUVmax. Cette thèse ouvre ainsi des perspectives de nouvelles indications de la TEP-TDM au FDG dans la prise en charge des carcinomes épidermoïdes des VADS, soulève des problématiques de recherche avec notamment l’émergence des nouveaux traceurs permettant de caractériser au mieux la cellule tumorale et s’inscrit dans une volonté actuelle d’une médecine préventive et prédictive personnalisée

Intérêt de la TEP au 18F-FDG dans le bilan de surveillance des patients traités pour carcinome épidermoïde des VADS

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

Intérêt pronostique de la Tomographie par emission de positons au 18F-Fluorodésoxyglucose dans Ie bilan d'extension des carcinomes epidermoïdes des Voies Aérodigestive Supérieures

Le carcinome épidermoide (CE) des voies aero-digestives supérieures (VADS) est une pathologie particuliérement incidente en France et au pronostic relativement sombre. La tomographie par émission de positons (TEP) au 18-Fluorodésoxyglucose (FDG) est une technique d'imagerie fonctionnelle actuellement largement utilisée en oncologie. L'objectif de cette étude a été d'évaIuer l'intérêt pronostique de paramètres cinétiques de diffusion intratumorale du FDG et de les comparer avec des facteurs pronostiques cliniques (age, sexe, stade AJCC) ou biologiques (index Ki67, expression de p53 et Cycline D1) reconnus ou en cours d'évaIuation. La pente initiale de captation de Ia tuméur (CO.k) a été évaluée à partir d une modélisation bicompartimentale sans sortie selon Patlak. La différence de SUV tardif ( SUVmax60 120) a été calculée à partir d'une méthode en 2 points (acquisition 1h et 2h aprés injection). Leur valeur prédictive de Ia survie sans récidive (EFS) et de Ia survie globale (OS) a été recherchée par analyse statistique univariée et multivariée selon un modele de Cox. Ce travail prospectif a inclus 66 patients (60H/6F), de 61 +/- 9 ans d age moyen au diagnostic. En analyse univariée, outre l âge et Ie stade tumoral, Ie SUVmax60-120 était prédictif de I'EFS (p=0.002) et de I OS (p<0.001), alorsque Ie C0.k était prédictif uniquement cle l EFS (p=0.02) et non de l OS (p=0.11). En analyse multivariee, Ie SUVmax60-120 restait un facteur prédictif indépendant de I'EFS (p=0.02) et de I OS (p=0.005), et Ie C0.k de I'EFS (p=0.04). Nos résultats suggérent donc I'interét pronostique de Ia cinétique de captation intratumorale du radiotraceur en TEP-FDG, réalisée dans Ie cadre du bilan d'extension initial des CE des VADS.BREST-BU Médecine-Odontologie (290192102) / SudocSudocFranceF