Parametric Imaging in Positron Emission Tomography for Patient With Lung Cancer

In oncology, Positron Emission Tomography imaging with 18Fluor-FDG quantifies glucose metabolism lesions. Conventionally, the metabolism is quantified using the Standard Uptake Value (SUV) from a static acquisition obtained 60 minutes post-injection. Some teams reported SUV variation coefficients as high as 30% in NSCLC lesions for repeated PET examinations in patients without treatment. Moreover, information regarding the binding kinetics of 18Fluor-FDG by tumor cells is not accessible through this method. Much more elaborated FDG quantification methods and considered as reference methods exist in PET imaging (compartmental analysis, Patlak). Simplified kinetic methods have also been proposed which correlate better with Patlak reference method than the conventional SUV. The investigators proposed a new methodological approach to obtain the parametric information in PET. This approach allows to define new indexes (average percentage of FDG-metabolized or not metabolized; time required to metabolize 80% of FDG). The approach has been clinically evaluated in a pilot study for the differentiation between benign and paraganglioma lesions. Tsuchida observed that the parametric PET imaging allowed histological differentiation of subtypes of lung tumors, reflecting the difference in glucose transporters and hexokinase between adenocarcinoma and squamous cell carcinoma. Xue et al showed that the FDG uptake (based on the only SUV) could be a tool to predict the subtype and thus tumor staging in patients suffering from NSCLC. The investigators can then hypothesize that some subtype of lung tumor, with increased proliferation rate (kinetic indexes k3, Ki or other parameters offered by our previous work), will be more sensitive to radiotherapy and thus the evaluation of tumor subtype by PET would allows radiotherapy adaption accordingly. This study is a preliminary methodological study , strictly descriptive and will only assess the comparison of measurements obtained on a parametric imaging and imaging "static" in patients suffering from NSCLC . The measures of the uptake and volumes estimated by two approaches will be correlated and compared with the 1 year clinical outcome (primary objective). An ancillary study will assess the relevance of the approach to detect, at the tumor level , an early recurrence of the disease. For this, the images acquired during the radiotherapy treatment (at 42Gy) will be analyzed retrospectively and the correlation with the images to 3 months or 1 year of relapsing patients will be analyzed.