Abstract: Objective:To study the value of Biograph Sensation 16positron emission tomography - computed tomogra -phy (PET-CT) in diagnosing neck lymph node (LN) metastasis of rabbit nasopharyngeal VX 2 carcinoma. Methods:After the establishment of 30rabbit nasopharyngeal VX 2 carcinoma models, 18F-deoxyglucose ( 18F- FDG) PET-CT was performed on the Biograph Sensation 16PET-CT machine and standard uptake value (SUV) was measured. Then anatomical and pathological diagnoses were completed. Neck LN images were observed and compared with the results of the anatomical and pathological findings. Results: (1) A total of 53neck LNs were collected from30nasopharyngeal VX 2 carcinoma rabbits and 42neck LNs were pathologically confirmed with metastasis. Twenty-eight rabbits had neck lymph node metastasis and the metastatic rate was 93.3% (28/30). (2) SUVs of 28positive LNs diagnosed by18F-FDG PET-CT were 3.820 ± 1.658 . Short diameter of positive LNs was significantly longer than that of false negative LNs ( t=5.599 , P=0.000 ), 0.83± 0.37cm and 0.38± 0.15cm, respectively. (3) The diagnostic sensitivity of 18F-FDG PET-CT was0.250 and 0.833 for LNs with the short diameter <0.5cm and ≥0.5cm, respectively, with a significant difference ( t=13.125 , P=0.000 ). The diagnostic accura -cy for LNs with short diameter <0.5cm was significantly different from that for LNs with short diameter ≥0.5cm ( t=4.837 , P=0.028 ). The accuracy was 0.571 and 0.844 , respectively ( t=4.837 , P=0.028 ). (4) When there were micro-metastases only in -side LNs or subcapsular invasion, PET-CT could find some metastatic LNs but with more false negative LNs. Conclusion: Biograph sensation 16PET-CT is a useful tool to detect the neck LN metastasis of rabbit nasopharyngeal VX2 carcinoma. The diagnostic sensitivity and accuracy were high and the specificity was100 %.18F-FDG PET-CT was reliable to detect the neck LNs with short diameter ≥0.5cm. 18F-FDG PET-CT could find micro-metastases only inside LNs or subcapsular invasion.