Diagnostic Significance of Single Center, Open and Prospective Evaluation of <Sup>18<Sup>F-FDG PET/CT Dynamic Imaging and Genomic Sequencing in Detecting Metastatic Lesions and Differentiating Multiple Primary Lung Cancer From Intrapulmonary Metastases of Non-small Cell Lung Cancer

Lung cancer is a malignant tumor with the highest morbidity and mortality in China and all over the world, in which non-small cell lung cancer (NSCLC) accounts for more than 85% of all categories [1-2]. Although the precision medicine has greatly improved the survival time of patients with NSCLC, most patients still have recurrence and metastasis after a period of time [3]. The nature of tumorigenesis, development and metastasis is a series of biochemical processes, such as abnormal gene expression and metabolism, dysfunction and structural change. Early prediction of tumor metastasis and accurate and timely clinical intervention will not only help clinicians to formulate treatment plans, but also reduce unnecessary side effects and medical expenses with ineffective treatment. 18F-FDG-PET scans can reflect metabolic changes at cellular and molecular level, and the metabolic information are transmitted earlier than anatomical changes. Detection of 18F-FDG uptake, analysis of tumor metabolism, tissue blood flow perfusion, receptor, and so on, can provide a theoretical basis for monitoring the therapeutic efficacy of lung cancer by PET [4].

As a new imaging technique, 18F-FDG PET/CT plays a more and more important role in the diagnosis of tumor. 18F-FDG PET/CT reflects the process of glucose metabolism in tumor tissue. The diagnosis of benign and malignant tumors is based on the difference of glucose metabolism activity between tumor cells and normal tissue cells. 18F-FDG is the isomer of glucose, which participates in the process of glucose metabolism. Because it cannot produce hexose diphosphate because of its deoxidation, it cannot participate in the next metabolism, and it is retained in cells. Due to the high expression of glucose transport mRNA,the level of Glut-1 and Glut-3 increased, the expression of hexokinase increased, and the level of glucose-6-phosphatase decreased, which resulted in an increase of 18F-FDG uptake in tumor cells [5]. Molecular imaging using 18F-FDG PET / CT can provide metabolic information, which can make benign and malignant tissues differentiate better, and reveal the functional abnormalities before structural damage [6]. However, the current PET/CT scans reported in the relevant literature are based on conventional static scans, i.e. the image data is based on a static take-up image of the tracer in tissue obtained at a fixed time point after the injection of 18F-FDG. To improve, the investigators propose to use dynamic data scanning, which captures the dynamic data of whole body tissues collected from the moment of injecting 18F-FDG to an hour. Dynamic scans can provide information on the dynamic changes in tracer metabolism and distribution in tissues over time, so they provide a richer metabolic and distributional pattern of tumor foci and metastases than static scans. Therefore, the aim of this study is to make up for this gap by performing a dynamic scan of 18F-FDG PET/CT on newly diagnosed patients with non-small cell lung cancer. The lesions and/or metastases are performed for biopsy. Pathological and genomic studies are performed. The differences between tumor images and tissues are compared at the same time. 18F-FDG PET/CT dynamic imaging is explored in non-small cell lung cancer metastases for the diagnostic value.At the same time, the ability to differentiate multiple primary lung cancer from intrapulmonary metastases of 18F-FDG PET/CT dynamic imaging will be dissussed .