Application of Dynamic 18 F-FDG PET/CT for Distinguishing Intrapulmonary Metastases from Synchronous Multiple Primary Lung Cancer

It has been a big challenge to distinguish synchronous multiple primary lung cancer (sMPLC) from primary lung cancer with intrapulmonary metastases (IPM). We aimed to assess the clinical application of dynamic 18 F-FDG PET/CT in patients with multiple lung cancer nodules. We enrolled patients with multiple pulmonary nodules who had undergone dynamic 18 F-FDG PET/CT and divided them into sMPLC and IPM groups based on comprehensive features. The SUV max , fitted [Formula: see text] value based on dynamic scanning, and corresponding maximum diameter ([Formula: see text]) from the two largest tumors were determined in each patient. We determined the absolute between-tumor difference of [Formula: see text] and [Formula: see text] ([Formula: see text]; [Formula: see text]) and assessed the between-group differences. Further, the diagnostic accuracy was evaluated by ROC analysis and the correlation between [Formula: see text] and [Formula: see text] from all groups was determined. There was no significant difference for [Formula: see text] between the IPM and sMPLC groups, while the IPM group had a significantly higher [Formula: see text] than the sMPLC group. The AUC of [Formula: see text] for differentiating sMPLC from IPM was 0.80 (cut-off value of [Formula: see text], sensitivity 79%, specificity 75%, [Formula: see text]). There was a good correlation (Pearson [Formula: see text], 95% CI: 0.79-0.96, [Formula: see text]) between [Formula: see text] and [Formula: see text] in the IPM group but not in the sMPLC group (Pearson [Formula: see text], [Formula: see text]). Dynamic 18 F-FDG PET/CT could be a useful tool for distinguishing sMPLC from IPM. [Formula: see text] calculation based on Patlak graphic analysis could be more sensitive than SUV max in discriminating IPM from sMPLC in patients with multiple lung cancer nodules.