Objective: It remains controversial whether positron emission tomography (PET) with 2-deoxy-2-[F-18]fluoro-D-glucose (F-18-FDG) can differentiate between benign and malignant musculoskeletal tumors. To uncover the mechanism of F-18-FDG accumulations, we analyzed the correlation between the F-18-FDG accumulation and the expression of glucose transporter 1 (Glut-1) and hexokinase II (HK-II) in benign and malignant musculoskeletal tumors.
Methods: The maximum standardized uptake values (SUVmax) of F-18-FDG in 24 benign and 26 malignant musculoskeletal tumors were compared with the histologic malignancies, and the expression of Glut-1 and HK-II was analyzed by immunohistochemistry.
Results: The SUVmax for malignant tumors (6.33+/-4.79) was significantly higher than those with benign tumors (3.47+/-3.12, P<0.01). The expression of Glut-1 was high in 12 patients (all malignant) and low in 38 patients (24 benign and 14 malignant), and the expression of HK-II was high in 36 patients (11 benign and 25 malignant) and low in 14 patients (13 benign and 1 malignant). Cases with high expression of Glut-1 and HK-II at immunohistochemistry showed a higher SUVmax than those with low expression (Glut-1 8.03+/-5.10 and 3.98+/-3.53, P<0.01; HK-II 5.73+/-4.49 and 2.99+/-3.02, P<0.01). No significant dividing threshold of the SUVmax of F-18 FDG was found for the differential diagnosis between benign and malignant tumors or for the expression of Glut-1 and HK-II.
Conclusions: The limited capability of F-18 FDG-PET in the differential diagnosis of musculoskeletal tumors is owing partly to the various levels of Glut-1 and HK-II expression in individual tumors.