Inclusion Criteria:  Volunteered to participate in this study and signed informed consent; Age range from 18 to 70 years; Clinically highly suspected oral cancer and recurrence after treatment, obtaining pathology results and planning surgery; Willing and able to follow schedule visits, treatment plans and laboratory tests; The clinical laboratory general biochemical examination (heart, liver, kidney, blood routine) and other indicators are in the normal range or abnormal without clinical significance.  Exclusion Criteria:  Female patients who plan to become pregnant within 6 months, or are pregnant or breastfeeding; Those who are allergic to test drugs, allergic constitution, or allergic to multiple drugs; People with poor general condition, their heart, lung, liver, kidney and other important organ functions cannot tolerate surgery; Before the injection of 18F-FDG, the fasting blood glucose level exceeded 11.0 mmol/L; The weight exceeds 100 kg; Patients with claustrophobia; Those who cannot tolerate lying supine for 15~30 minutes; Researchers think it is inappropriate to participate in this clinical trial; Those who have participated in clinical trials or are participating in other clinical trials in the past month.