PET-CT can be highly suggestive of lung cancer, but it does not confirm whether it is lung cancer or not. On PET-CT, if it is lung cancer, the metabolism of the masses in the lungs will be significantly higher. In particular, some mediastinal lymph nodes, some of which cannot be identified on CT as lymph node metastases arising from lung cancer or enlarged lymph nodes caused by benign inflammation. PET-CT can better identify whether these mediastinal lymph nodes are metastases or benign ones, and PET-CT can also better detect whether there are metastases in other parts of the body, so PET-CT is mainly used for clinical staging before treatment and monitoring whether there is recurrence and metastasis of lung cancer after treatment. If you want to diagnose whether it is lung cancer or not, you need to undergo surgical resection or puncture biopsy, take biopsy by bronchoscopy and send it to pathology for laboratory test before the final diagnosis can be made.