ROC analysis of ordered subset expectation maximization and filtered back projection technique for FDG-PET in lung cancer

The purpose of this study was to evaluate the image quality and discriminative ability of fluoro-deoxy-D-glucose positron emission tomography (FDG-PET) images reconstructed by conventional filtered back projection (FBP) and ordered subset expectation maximization (OSEM) in patients with lung cancer. Thirty-six subjects including normal controls and lung cancer patients underwent whole body PET scan (emission 3 min, transmission 1 min) using a GE Advance Scanner after the administration of approximately 370 MBq of FDG. The raw data were then reconstructed by conventional FBP and OSEM. The PET images were interpreted by two observers with random exposure of normal and diseased cases for transverse and coronal sections. The results were evaluated using receiver operating characteristic (ROC) curve analysis. The image quality of 36 subjects including normal controls and lung cancer patients reconstructed by OSEM was generally superior to FBP in terms of visual analysis. FBP without attenuation correction had better image contrast than OSEM, although it had poor image quality. ROC analysis indicated that for this limited set of studies OSEM with attenuation correction out-performed conventional FBP in terms of its discriminative ability of lung cancer with FDG-PET. The results indicated that OSEM provides better image quality and superior discriminative ability than conventional FBP for diagnosis of lung cancer by whole body FDG-PET.