ABSTRACT
Objective To study 18F-deoxyglueose positron emission tomography computed tomo graphy(18 FDG PET-CT) in the diagnosis of cervical lymph node(LN) metastasis from rabbit nasopharyngeal VX2 carcinoma.Methods Nasopharyngeal VX2 carcinoma model using 30 rabbits was established. 18 FDG PET-CT,MRI and pathological diagnosis were performed and compared.ResultsFifty-three cervi cal LNs were picked up from resected specimens of 30 rabbits with nasopharyngeal VX2 carcinoma.There were 42 pathologically confirmed positive LNs.Positivity rate was significantly correlated with the volume and the shortest diameter of the LNs (r = 9.18,P =0.007 ; r = 2.77,P = 0.008).The diagnostic sensitivity of PET-CT was 96% (24/25) and 29% (5/17) for LNs with volume >0.5 cm3 and ≤0.5 cm3 ,83% (25/30) and 33% (4/12) for LNs with the shortest diameter ≥0.5 cm and < 0.5 cm,respectively.The diagnostic sensitivity,specificity and accuracy of PET-CT was 69% (29/42) ,100% (11/11) and 95% (40/42) ,com paring with 60% (25/42) ,91% (10/11) and 83% (35/42) of MRl,respectively.The volume measured by PET-CT images was not significantly different from the pathologically measured volume (t =-1.23,P = 0.233) ,while the volume measured by MRI was significantly different from the pathologically measured vol ume (t =-3.99,P = 0.001).Conclusions The sensitivity,specificity and accuracy of PET-CT are better than those of MRl,especially for the cervical lymph nodes with volume >0.5 cm3 or the shortest diameter ≤ 0.5 cm.PET-CT also can be used to detect the smaller metastatic lymph nodes,though the false negative rate is higher.