“…Recently, CT was recommended by the National Comprehensive Cancer Network for the screening of lung cancer in high risk groups. However, little evidence supported this recommendation, and lots of problems still exist in the application of this technique (Field et al, 2012;Spiro and Navani., 2012;Tanner et al, 2012;Xiang et al, 2013). Similarly, PET technique also has limitations in detecting and staging lung cancer, including low spatial resolution, and inconspicuous contrast among different tissues, etc (De Wever et al, 2007).…”