Assessment of soft tissue lesions suspicious for liposarcoma by F18-deoxyglucose (FDG) positron emission tomography (PET)

BACKGROUND: F18-deoxyglucose (FDG) positron emission tomography (PET) is a promising imaging technique. The aim of this study was to investigate the use of FDG PET in patients with suspected liposarcomas (LS). PATIENTS AND METHODS: Forty-two masses were studied. The FDG uptake was estimated in tumor (T) and normal tissue (NT). The data were analyzed with respect to pathological findings. RESULTS: Pathology revealed 11 primary LS, 14 locally recurrent LS, 5 other sarcomas, 1 inflammation, 1 lymphoma and 10 benign lesions. FDG uptake (T-to-NT ratio) in 25 LS corresponded with the histological subtype. Pleomorphic, mixed and myxoid LS showed an increased T-to-NT ratio and were thus visualized. Four out of six well-differentiated LS presented a low FDG uptake. Like subtype, the tumor grade also corresponded to FDG uptake. The T-to-NT ratio of higher grade LS, contrary to low grade LS, was uniformly increased. Primary LS were distinguishable from benign tumors, while other sarcomas, inflammation and lymphoma were not. Recurrence was detected with a sensitivity of 86% and a specificity of 100%. False-negative diagnoses occurred only in well-differentiated recurrences. CONCLUSION: FDG uptake in LS correlates with the histological subtype and tumor grade. The diagnostic value of FDG PET in LS, therefore, is influenced by histomorphological parameters. Our data suggest that pleomorphic, mixed and higher-grade LS recurrences are preferentially amenable to FDG PET imaging.