The accuracy of PET-CT in the diagnosis of T and N stages of lung cancer is higher than that of CT, and the meta-analysis shows that its sensitivity is 85% and specificity is 90%, both of which are higher than that of CT (P<0.001). Some studies have shown that the false positive rate of PET diagnosis of lymph nodes is 13%-22% and the false negative rate is 5%-7%. 2. In the diagnosis of brain metastases, the sensitivity of PET is only 60%, which is usually considered less accurate than CT or MRI. 3. In the diagnosis of bone metastases, new metastatic lesions are found in 7-11% of patients after adding PET to CT and bone scan examinations. A study comparing PET and bone scan showed that the sensitivity of PET was 92% and specificity was 99%, while bone scan was 50% and 92%, respectively. 4. The accuracy of PET in diagnosing adrenal metastases is better, with a false positive rate of 0-8%.