Abstract: Objective To investigate the value of 18F-FDG PET/CT in differential diagnosis of solitary tubercular nodule (STN) and clinical stageⅠnon-small cell lung cancer (NSCLC). Methods The PET/CT images of STNs confirmed from January 2012 to December 2016 were collected, and the PET/CT images of clinical stageⅠNSCLC diagnosed from January to December 2016 were used as controls. The CT images and metabolic features were compared between the two groups. Results The lesion presented as round or round like were 70.6% in the group of clinical stageⅠNSCLCs and 30.8% in the group of STNs, respectively. The difference was statistically significant (P<0.05). In the group of clinical stageⅠNSCLCs, 26.5% of the lesion was shown with short spikes but no short spikes in the group of STNs. The difference was statistically significant (P<0.05). The distribution, size, and pleural tag of lesions showed no significant differences between the two groups (P>0.05). The average SUVmax in the group of clinical stageⅠNSCLCs was higher than that in the group of STNs, but the difference was not statistically significant (P>0.05). There was no significant differences in terms of tumor metabolic volume (TMV) and total lesion glycolysis (TLG) between the two groups (P>0.05). Twelve cases in the group of STNs received delayed imaging, with the lowest retention index (RI) of 0%, the highest 84% and a mean of 46.53±21.22. Twenty-seven cases in the group of clinical stage I NSCLC received delayed imaging, with 1 case showing an RI of -10.20. Among the 27 cases, the maximum value was 56%, and the mean was 24.91±15.51. The RI of STNs group was significantly higher than that in the group of clinical stageⅠNSCLC (P<0.05). Conclusion The morphology, short spike sign, and the value of RI are key points facilitating the differential diagnosis of STN and clinical stageⅠNSCLC.

Key words: Solitary pulmonary tubercular nodule, Non small cell lung cancer/gradeⅠ, PET/CT, Differential diagnosis