QUANTITATIVE EVALUATION OF THERAPEUTIC RESPONSE BY FDG PET-CT IN METASTATIC BREAST CANCER

Purpose To assess the therapeutic response for metastatic breast cancer with 18F-FDG PET, this retrospective study aims to compare the performance of 6 different metabolic metrics with PERCIST, PERCIST with optimal thresholds and an image-based parametric approach.MethodsThirty six metastatic breast cancer patients underwent 128 PET scans and 123 lesions were identified. In a per-lesion and per-patient analysis, the performance of 6 metrics: SUVmax (maximum Standardized Uptake Value), SUVpeak, SAM (Standardized Added Metabolic activity), SUVmean, metabolic volume (MV), TLG (total lesion glycolysis) and a parametric approach (SULTAN) were determined and compared to the gold standard (defined by clinical assessment and biological and conventional imaging according RECIST 1.1). The evaluation was performed using PERCIST thresholds (for per-patient analysis only) and optimal thresholds (determined by the Youden criterion from the Receiver Operating Characteristic curves).ResultsIn the per-lesion analysis, 210 pairs of lesion evolutions were studied. Using the optimal thresholds, SUVmax, SUVpeak, SUVmean, SAM and TLG were significantly correlated with the gold standard. SUVmax, SUVpeak and SUVmean reached the best sensitivity (91 %, 88 % and 83% respectively), specificity (93%, 95% and 97% respectively) and negative predictive value (NPV, 90%, 88% and 83% respectively). For the per-patient analysis, 79 pairs of PET were studied. The optimal thresholds compared to the PERCIST threshold did not improve performance for SUVmax, SUVpeak and SUVmean. Only SUVmax, SUVpeak, SUVmean and TLG were correlated with the gold standard. SULTAN also performed equally: 83% sensitivity, 88% specificity and NPV 86%.ConclusionsThis study showed that SUVmax and SUVpeak were the best parameters for PET evaluation of metastatic breast cancer lesions. Parametric imaging is helpful in evaluating serial studies

CLINICAL AND SURVIVAL IMPACT OF FDG PET IN PATIENTS WITH SUSPICION OF RECURRENT OVARIAN CANCER: A 6-YEAR FOLLOW-UP

Background: The aim of this retrospective study was to evaluate the contribution of FDG PET to the clinical management and survival outcome of patients (pts) suspected of recurrent ovarian carcinoma, with the hypothesis that early diagnosis of recurrent ovarian cancer may improve overall survival. Methods: 53 FDG PET/CT scans were retrospectively analyzed for 42 pts. CT and PET/CT findings were confirmed by imaging and clinical follow-up, and/or pathology which was considered as the gold standard diagnosis. The treatment plan based on CT staging was compared with that based on PET/CT findings. Medical records were reviewed for pts characteristics, progression free survival (PFS) and overall survival (OS). Progression-free survival (PFS) and overall survival (OS) were analyzed using the Cox proportional hazards regression model. Results: The final diagnosis of recurrence was established pathologically (n=16), or by a median clinical follow-up of 6.5 years (range 0.5-7.5) after the PET/CT (n=37). PET/CT provided a higher detection sensitivity (92.2%, 47/51) than CT (60.8%, 31/51) (p<0.001). Globally, PET/CT modified the treatment plan in 56.6% (30/53) of and in 65,2% (14/23) when the CT was negative prior to PET/CT. In 30 cases, that benefited from a modified treatment plan, these changes led to the intensification of a previous treatment procedure in 83.3% (25/30), and to a reduction in the previous treatment procedure in 16.6% of cases (5/30). The Cox regression multivariate analysis showed that the number of lesions visualized by CT, and presence of lung lesions detected by PET/CT, were significantly associated with PFS (p=0.002 and p = 0.035, respectively). Conclusion: On account of its impact on treatment planning, and especially patient outcome, FDG PET is a valuable diagnostic tool for cases of suspected ovarian cancer recurrence