D. Williaume

Tomographie par émission de positons au (18F)-fluorodésoxyglucose dans les cancers du col utérin : évaluation ganglionnaire et valeur pronostique/prédictive des données de la tumeur primitive

PURPOSE In cervix carcinoma: (a) to evaluate the ability of ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the lymph node detection; (b) to investigate the prognostic and predictive value of the primary cervical PET parameters. PATIENTS AND METHODS Ninety patients treated for cervix carcinoma and evaluated initially by MRI and FGD PET were included. The performances of FDG-PET for lymph node detection (relatively to the lymph node dissection) have been described (sensitivity, specificity, positive predictive value and negative predictive value). PET tumour parameters analyzed were: maximum standard uptake value (SUVmax), the volume and the maximum diameter. The prognostic and predictive values of these parameters were investigated. The tumour response was evaluated on surgical specimens. RESULTS PET detected the cervical tumour with a sensitivity of 97% (mean values: SUVmax=15.8, volume=27 mm(3), maximum diameter=47). For the detection of the lymph nodes, the values of sensibility, specificity, positive predictive value and negative predictive value were: 86, 56, 69 and 78% in the pelvic, and 90, 67, 50 and 95% for the para-aortic area, respectively. The SUVmax was correlated with histologic response (P=0.04). The frequency of partial histological response was significantly higher for tumour SUVmax>10.9 (P=0.017). The maximum PET diameter and pathologic response had an impact on disease-free survival and overall survival in multivariate analysis (P<0.05). CONCLUSION PET has high sensitivity in detecting pelvic and para-aortic lymph nodes. Some primary cervical tumour PET parameters are useful as prognostic and predictive factors.

PD-0356: 18F-FDG PET parameters during radio-chemotherapy to predict tumor recurrence in cervical cancer

These prospective study included 53 patients treated for locally advanced cervical cancer by external beam radiation therapy with concurrent chemotherapy, followed by brachytherapy and + surgery. All patients were evaluated by FDG PET/CT before treatment (PET1) and at 40 Gy (PET2). PET-parameters analysed were: maximum standardized uptake value (SUVmax1, SUVmax2), metabolic tumour volume (MTV1, MTV2), and total lesion glycolysis (TLG1, TLG2). MTV1 and MTV2 were automatically segmented (region-growing) using different thresholds (between 30% and 80% of SUVmax). The recurrence were defined based on clinical examination, MRI and PET imaging. Median follow-up was 30 months [range: 8-60]. A total of 13 patients developed disease recurrence and 7 died of disease. The predictive capabilities of the PET parameters to predict overall recurrence were tested using Cox proportional hazards regression models (p values calculated). Comparisons among different models were done by calculating the Harrel’s C-index (c).

Treatment plan library based on population shape analysis for cervical adaptive radiotherapy.

External radiotherapy is extensively used to treat cervix carcinoma. It is based on the acquisition of a planning CT scan on which the treatment is optimized before being delivered over 25 fractions. However, large pertreatment anatomical variations, hamper the dose delivery accuracy, with a risk of tumor under-dose and healthy organs over-dose resulting to recurrence and toxicity. We propose to generate a patient-specific treatment library based on a population analysis. First, the cervix meshes of the population were registered towards a template anatomy using a deformable mesh registration (DMR). The DMR follows an iterative point matching approach based on the local shape context (histogram of cylindrical neighbor coordinates and normalized geodesic distance to the cervix base), a topology constraint filter, a thin-plate-spline interpolation and a Gaussian regularization. Second, a standard principal component analysis (PCA) model was generated to estimate the dominant deformation modes of the population. Posterior PCA was computed to generate different potential anatomies of the target. For a new patient, her cervix was registered towards the template and her pre-treatment library was modeled. This method was applied on the data of 19 patients (282 images), using a leave-one-patient-out. The DMR was evaluated using point-to-point distance (mean: 1.3 mm), Hausdorff distance (5.7 mm), dice coeffi- cient (0.96) and mean triangle area difference (0.49 mm2 ). The performances of two modeled libraries (2 and 6 modeled anatomies) were compared to a classic pre-treatment library based on 3 planning CTs, showing better results according to both target and healthy organs coverage.

Tomographie par émission de positons au (18 F)-fluorodésoxyglucose dans les cancers du col utérin: évaluation ganglionnaire et valeur pronostique/prédictive des données de la tumeur primitive [((18)F)-fluorodeoxyglucose PET/CT in cervix cancer: lymph node assessment and prognostic/predictive value of primary tumour analysis].

PURPOSE In cervix carcinoma: (a) to evaluate the ability of ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the lymph node detection; (b) to investigate the prognostic and predictive value of the primary cervical PET parameters. PATIENTS AND METHODS Ninety patients treated for cervix carcinoma and evaluated initially by MRI and FGD PET were included. The performances of FDG-PET for lymph node detection (relatively to the lymph node dissection) have been described (sensitivity, specificity, positive predictive value and negative predictive value). PET tumour parameters analyzed were: maximum standard uptake value (SUVmax), the volume and the maximum diameter. The prognostic and predictive values of these parameters were investigated. The tumour response was evaluated on surgical specimens. RESULTS PET detected the cervical tumour with a sensitivity of 97% (mean values: SUVmax=15.8, volume=27 mm(3), maximum diameter=47). For the detection of the lymph nodes, the values of sensibility, specificity, positive predictive value and negative predictive value were: 86, 56, 69 and 78% in the pelvic, and 90, 67, 50 and 95% for the para-aortic area, respectively. The SUVmax was correlated with histologic response (P=0.04). The frequency of partial histological response was significantly higher for tumour SUVmax>10.9 (P=0.017). The maximum PET diameter and pathologic response had an impact on disease-free survival and overall survival in multivariate analysis (P<0.05). CONCLUSION PET has high sensitivity in detecting pelvic and para-aortic lymph nodes. Some primary cervical tumour PET parameters are useful as prognostic and predictive factors.