Valeur pronostique de la TEP/TDM dans le bilan initial du cancer du col utérin : SUVmax de la tumeur primitive et stadification ganglionnaire

PurposeWe investigated the prognostic significance of F-18 fluorodeoxyglucose (FDG) uptake measured as maximum Standardized Uptake Value (SUV_max) in primary tumor by positron emission tomography/computed tomography (PET/CT) in cervical cancer. The secondary objective was to determine the accuracy of the PET/CT for detecting pelvic lymph node (PLN) and para-aortic lymph node (PALN) metastases.MethodsThis retrospective study included 49 consecutive patients with stage IB1 to IVB cervical cancer. Univariate analysis was performed to determine the relationships between SUV_max value and pathological prognostics factors. Survival was estimated by Kaplan-Meier method. The gold standard of LN metastases was histologic.ResultsA significant difference in SUV_max was observed between stage I and stage II, stage I and stage IV and tumor size ≤ 4 cm and > 4 cm (P = 0.0001). There was a significant correlation between the SUV_max and tumor maximal size (r = 0.597) (P < 0.0001). PLN metastasis was found to be predictive of progression-free survival (P = 0.0007). The negative predictive value (NPV) of the PET/CT for PALN was 100% for locally advanced cervical carcinoma in 24 patients. The specificity and NPV of the PET/CT for PLN in eight early-stage cervical cancer were 100% and 87.5% (7/8) respectively. The PET/CT false-negative PLN measured less than 2 mm.ConclusionOur results demonstrate a correlation between SUV_max and tumor maximal size, which represents an indicator of tumor aggressiveness. PET/CT is effective to predict the absence of PALN in locally advanced cervical carcinoma. PET/CT is not sufficient to predict PLN in early-stage cancer without lymphadenectomy.     

La TEP-TDM au 18FDG a-t-elle un intérêt dans la stadification ganglionnaire des mélanomes malins cutanés cervicofaciaux bénéficiant de la technique du ganglion sentinelle ? À propos de 22 cas

Background and objectivesIn N0 cutaneous head and neck melanoma, sentinel lymph node biopsy (SLNB) is less reliable and accurate than in trunk or extremities melanoma (false negative cases and spotting failure). The aim of our study was to assess the utility of PET-CT ¹⁸FDG in a specific group of N0 patients, combined with SLNB.Patients and methodsTwenty-two patients with N0 cutaneous head and neck melanoma were retrospectively reviewed. All of them had underwent PET-CT and SLNB before surgery. Average follow-up time was 17 months (1–44).ResultsAt least one sentinel lymph node (SLN) was identified in 20 patients. Ten patients (50%) had metastatic SLN. Among these 10 N+ patients, PET-CT was positive for occult nodal metastases for only two patients. During follow-up, two patients had cervical nodal recurrence, whereas SLNB was negative. PET-CT was also negative for these two patients. SLNB and PET-CT sensitivity were respectively 83 and 18%. PET-CT specificity was 84% (regarding neck sides).ConclusionIn this specific population with N0 cutaneous head and neck melanoma, PET-CT sensitivity is too low and failed to detect occult nodal metastases in two patients with false negative SLNB. Consequently, PET-CT seems to be not useful for nodal staging N0 cutaneous head and neck melanomas, in which SLNB is the most accurate technique.     

Apport de la TEMP/TDM pour la détection du ganglion sentinelle dans les cancers du col utérin et de l’endomètre

The sentinel lymph node procedure is still under evaluation for the management of cervical and endometrial carcinomas. The aim of our study was to determine the diagnostic accuracy of single-photon emission computed tomography/computed tomography (SPECT/CT) for preoperative sentinel lymph node mapping in uterine cancers. Sixty-eight patients with cervical (n = 42) or endometrial carcinoma (n = 26) underwent preoperative lymphoscintigraphy for sentinel node mapping. Sentinel node detection rate with conventional planar imaging was similar to that of SPECT/CT (87.1 versus 91.8 %) in the whole cohort. However, SPECT/CT detected a higher number of sentinel nodes in more than one third of patients, affected by either cervical or endometrial carcinoma. The rate of non or insufficiently contributive procedures (lack of uptake or unilateral uptake) in endometrial carcinomas was 47 % with conventional planar imaging, and 30 % with SPECT/CT. Sensitivity of both procedures for the detection of metastatic nodes was 81.8 %, compared to 100 % for the intraoperative combined detection (gamma probe sonde and blue dye). The impact of SPECT/CT for the sentinel lymph node detection in cervical and endometrial carcinomas needs further evaluation. Nevertheless, SPECT/CT may provide additional information when conventional planar imaging detects only unilateral uptake, may improve identification of atypical localizations, and facilitate surgical approach.     

Performances de la TEP au 18F-FDG dans la caractérisation initiale de la lésion primitive du cancer du sein

Objective¹⁸F-FDG PET/CT is for the moment not recommended for stage T of the TNM classification of breast cancer. The aim of our study was to evaluate the performance of ¹⁸F-FDG PET/CT in the initial staging of breast tumors. Tumor size, skin involvement and inflammation as well as the relationship between primary tumor maximum standardized uptake value (SUVmax) and histopathological grade (SBR), molecular tumor subtypes (luminal A and B, Her2 enriched, triple negative), estrogen receptors (ER), progesterone receptors (PR) and focality were evaluated.MethodsHistological reports of patients operated for breast cancer, without neoadjuvant chemotherapy, were compared to preoperative ¹⁸F-FDG PET/CT.ResultsSeventy-four patients who underwent surgery in 2016 were included. ¹⁸F-FDG PET/CT was able to visualize primary tumors in 91% and to correctly classify the T stage of the TNM classification in 81% of the cases, to detect multifocality in 73% and cutaneous and inflammatory breast cancers in 100%. The uptake intensity of ¹⁸F-FDG (SUVmax) was significantly correlated with histo-prognostic factors such as SBR grade (P = 0.02), lack of expression of estrogen receptors (ER) (P = 0.01) and progesterone (PR) (P = 0.02), positive HER2 status (P = 0.01) or triple negative subtype tumors (P = 0.02).Conclusion¹⁸F-FDG PET/CT provides relevant elements for local assessment, in particular, tumor focality and inflammatory character in addition to ensuring the regional and extension assessment.     

Intérêt de la TEP/TDM au 18FDG dans les sous-types histologiques agressifs de cancers thyroïdiens (oncocytaire et peu différencié)

IntroductionThe objective of our study was to evaluate the performance of ¹⁸FDG PET/CT in aggressive histological subtypes of differentiated cancer of the thyroid and its therapeutic impact.MethodThirty-three patients (22 Hürthle cell carcinoma and 11 poorly differentiated carcinoma) who underwent FDG PET/CT were retrospectively included. Nine scans have been performed for initial staging, 16 for suspicion of recurrence (with 11 having a rising Tg), 3 for the reassessment of metastatic disease under systemic treatment and 30 systematically during follow-up. The results of PET/CT were confronted with histological data and follow-up results.ResultsThirteen out of 18 positive scans were confirmed (8 locoregional recurrences and 5 distant metastases). The majority of them were performed for a suspicion of recurrence (8) or for initial staging (2). The sensitivity, specificity, PPV, and NPV were respectively 81.2%, 88.1%, 72.2% and 92.5%. For Hürthle cell carcinoma and poorly differentiated carcinoma, the sensitivity and specificity were respectively 100% vs. 57% and 86% vs. 93%. Systematic PET scans were most of the time negative (26/30) and in accordance with histological and follow-up results. It was the same in case of scans performed for undetectable initial Tg (16/22). PET/CT modified patient management in 14% of the cases.ConclusionThis study confirms the good performances of ¹⁸FDG PET/CT for initial staging and in case of elevated Tg during the follow-up of aggressive histological subtypes of thyroid cancer. It does not seem relevant in the absence of a suspicion of recurrence or in the case of undetectable initial Tg.     

Syndromes paranéoplasiques : intérêt de la tomographie par émission de positons (TEP) au 18F-fluoro-déoxyglucose (FDG)

BackgroundWe evaluated the performance of ¹⁸F-fluorodeoxyglucose (¹⁸FDG) positon emission tomography (PET) in the diagnosis of underlying malignancy in cases of suspected paraneoplastic syndrome (PS).Methods¹⁸FDG-PET was performed in 31 patients, clinically suspected to have PS. The PS were 34, among which 12 neurological diseases, eight endocrine, seven rheumatological, one dermatological and six vascular. We compared computed tomography (CT), iodine-enhanced most of the time, and ¹⁸FDG-PET reports to clinicians definitive conclusion at the end of the work-up and a follow-up period of, at least, two months.ResultsWe obtained a histological diagnosis of cancer for ten patients, but could only identify the primary site of malignancy for nine of them. ¹⁸FDG-PET showed six primary sites among which three were not seen on CT. CT disclosed four primary sites, among which one was not seen on ¹⁸FDG-PET. In one case, ¹⁸FDG-PET disclosed regional lymph node metastases whereas these were not identified by CT. Eleven non-neoplasic causes were evidenced, among which ¹⁸FDG-PET played a major role in three cases. Ten causes were still undetermined at the end of the study.ConclusionWhole-body ¹⁸FDG-PET study plays an important role in the identification of underlying malignancy in clinically suspected paraneoplastic syndromes; either by identifying the primary tumor or by directing biopsy of metastases. Furthermore, it can identify non-neoplasic causes.     

Intérêt du dosage de la testostérone biodisponible dans les dysérections

Is serum non-sex hormone binding globulin-bound (non-SHBG-bound) testosterone more sensitive than total testosterone (T) in men presenting érectile dysfonction? Non-SHBG-bound testosterone level has been shown to undergo decrease whereas SHBG level increases in middle-aged men without érectile dysfonction. Serum SHBG increase has been found in secondary organic etiology of érectile dysfonction. The aim of this work was to study hormonal status in men presenting érectile dysfonction. Serum SHBG, T, bioavailable T, luteinizing hormone (LH) and folliculin stimulating hormone (FSH) levels were measured in 40 men presenting érectile dysfonction. They were divided into four groups according to their etiology: psychogenic, vasculogenic, iatrogenic, and unknown etiologies. In order to consider the effect of the age, each group was compared with age-related healthy controls without any érectile dysfonction. Non-SHBG-bound-T decreased with age and SHBG increased, while serum T was similar in young and elderly control subjects. In the vasculogenic subjects, SHBG was higher than in the controls, but not significantly. In the patients with érectile dysfonction of unknown etiologies, non-SHBG-bound-T was lower than in the controls without increase of SHBG. In the psychogenic patients, SHBG was higher than in the controls while total T was similar in both groups. This study allowed to investigate androgen status of men suffering of érectile dysfonction according to their etiology. The following step would be to study the rate of success of appropriate hormonal therapy in patients in which peripheral hypogonadism occurs.     

Influence de la rhTSH sur la fixation du 18 FDG dans une population de 42 patients avec cancer différencié de la thyroïde suspect de récidive

PurposeThe role of positron emission tomography with 18 fluoro-deoxy-glucose (FDG-PET) in case of differentiated thyroid carcinoma recurrence is established. However, the influence of TSH levels on 18 FDG is still discussed. Our study aims at comparing respective performances of FDG-PET performed at low TSH levels and under rhTSH stimulation, when a recurrence of a thyroid carcinoma is suspected.Material and methodsForty-two patients have been included, in a prospective way; each of them has been explored by FDG-PET at low (PET1) and high TSH levels with Thyrogen^® (PET2). The number of hypermetabolic foci, the intensity of uptake, both visual and with Standardized Uptake Values (SUV) have been compared.ResultsPET1: 82 foci were detected, including 75 true positive (TP) and seven false positive (FP). Sensitivity by lesion is 85.23 and 58.6% on a patient basis. Twelve pathological sites, not visualized (false negative) in PET1, were seen under stimulation. PET2: 89 foci were detected, including 87 TP and two FP; two tumoral sites visualized with PET1 are not detected. Sensitivity by lesion is 97.75 and 75.9% on a patient basis. SUV are significantly higher under stimulation. In three patients, therapeutic strategy has been modified, based on PET2 data.ConclusionStimulation by rhTSH improves FDG-PET performances. Therefore, it is justified to resort to it in case of recurrence of differentiated thyroid carcinoma, when the usual workup is negative.     

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.     

Effets de la fluorescence résiduelle dans les tissus biologiques sur les signaux de fluorescence résolus temporellement par la méthode des éléments finis

A computational model based on finite element method is derived to examine how the simulated time-dependent signals are related to the presence of residual fluorescence in biological media surrounding a fluorescent object. We apply a subtraction technique on recorded data when imperfect uptake of fluorescing agent into the tumor is considered. We show the limits of the subtracting method for low target: background fluorescent absorption contrast by extracting the time to reach the half maximum and analyzing the maximum of the time-resolved signals versus target depth.     

Le MorphoTEP au FDG est un examen utile dans les cancers différenciés de la thyroïde avec élévation des anticorps antithyroglobuline

AimAssessment of the clinical impact of a PET/CT with FDG for the follow-up of differentiated thyroid cancer (DTC) with rising or positive thyroglobulin autoantibodies (AbTg) level and negative or inconclusive conventional imaging work-up.MethodologyThis retrospective study involves 15 patients seen in follow-up with confirmed DTC primarily treated with total thyroidectomy and Iodine-131. Patients presenting increased AbTg and a negative or non informative conventional workout were included. The results of the PET/CT were correlated with histology and/or clinical follow-up. The clinical impact was determined on a change of intention to treat, which was decided upon in multidisciplinary meetings, based on the PET/CT result.ResultsWe observed 10 true positive exams confirmed via histology in seven patients and via clinical follow-up in three on the average 33 months (20–53 months), three real negative exams with negative follow up of on the average 39.5 months (30–47 months), one false positive and one false negative. The intention to treat was modified in 73.3 % (11/15 patients). PET/CT showed sensitivity, specificity, positive predictive value, negative predictive value and accurancy of 91, 75, 90, 75, 86.6% respectively. There was a large and comparable dispersion of the AbTg values in both the true positive and the true negative groups, the kinetic of AbTg evolution could have a predictive value of a positive PET.Discussion/ConclusionPET/CT with FDG seems to be very useful in the therapeutic management of DTC in the case of AbTg increased or positive, in particular for the patients with N1 in the initial staging. Further studies are suggested to confirm the very promising negative predictive value and specificity of this exam in a larger number of patients.     

Impact de la méthode de segmentation dans la caractérisation des adénocarcinomes pulmonaires en TEP-TDM au 18FDG

ObjectiveThe treatment of lung adenocarcinomas is conditioned by the presence of certain genetic abnormalities. Certain quantitative parameters obtained from FDG PET-CT, at the voxel scale, provide tumour shape and texture characteristics and might predict their mutational status. Our objective was to determine the impact of the segmentation method in the characterization of lung adenocarcinomas in FDG PET-CT.MethodsForty-nine patients with pulmonary adenocarcinomas were retrospectively included, with their initial FDG PET-CT image. The studied tumours were big, heterogeneous and difficult to segment automatically. The automatic FLAB algorithm was used with and without manual adjustment. The parameters were extracted and compared to the ALK, PDL1, and KRAS status, in order to compare the performances of the two segmentation methods. Their performance was determined by the ROC curve method.ResultsSeveral parameters were significant to predict genetic status (AUC > 0.65). The best performing parameters were different according to the genes studied and according to the resampling methods used. The results were less dependent on resampling in automatic segmentation without manual adjustment. The best performing parameters were volume dependent parameters for segmentation with manual adjustment, and texture parameters for automatic segmentation without adjustment.ConclusionThe study of texture parameters is more efficient in automatic segmentation that is not manually adjusted, and it is advantageous to use a manual adjustment when studying volume-dependent parameters in the case of very heterogeneous tumors.