Study of the relationship between 18F-FDG coincidence SPECT/CT and histological classification of thymic epithelial tumors

LI Duo; LI Yawei; ZHANG Weihong; WANG Meng; LYU Pingxin

Abstract：Objective To investigate the relationship between 18F-FDG coincidence SPECT/CT and the world health organiza-tion malignant grade of thymic epithelial tumors (TET). Methods The 18F-FDG SPECT/CT imaging and CT imaging of seven-teen patients with pathologically proven thymic epithelial tumors were analyzed retrospectively and histological subtype. CT fea-tures,visual graded of 18F-FDG uptakes,radioactivity of the tumor,mediastinum and lung were recorded. Results There were seven patients classified into low-risk group (one type A,three type AB and three type B1) and ten patients were classified into high-risk group (two type B2, one type B3 and seven type C). WHO histological classification showed significant relationship with visual grade,T/L and T/M (Spearman correlation coefficients were 0.697,0.811 and 0.815, respectively. P value were 0.002,0.000 and 0.000). Accuracy was 88.2% for take visual grade higher than mediastinum as the cut-off to differentiate high-risk from low risk TET. There were no significant different between the two groups considering the CT findings including di-ameter, necrosis, calcification, lobulated, the infiltration of surrounded fat, metastasis, enhancement patten and tumor vessel. There were significant different between the two groups in visual grade(2.0 vs 3.7,P =0.001),T/L(5.4 vs 16.3,P =0.002) and T/M (1.2 vs 10.4, P =0.002). Conclusion There was significant relationship between FDG uptake and histological WHO classification of thymic epithelial tumors. Visual grade higher than mediastinum could be an easy and useful way to predict high-risk thymic epithelial tumors.