Prospective evaluation of soft tissue masses and sarcomas using fluorodeoxyglucose positron emission tomography

Background: The differentiation of soft tissue sarcoma (STS) from benign ma sses is difficult owing to their clinical and radiological similarities. Ac curate staging is hindered by the large number of sites at which metastases may be found. This study examined the value of whole-body [F-18]2-fluoro-2 -deoxy-D-glucose positron emission tomography (FDG PET) in patients present ing with soft tissue masses. Methods: Thirty patients with a soft tissue mass suspected to be malignant were evaluated with FDG PET. The images were evaluated qualitatively and qu antitatively for uptake of FDG to determine whether benign lesions could be differentiated from malignant tumours, and for the presence of metastases. Results: Thirty-one masses were removed from 30 patients; 12 were benign an d 19 were malignant STSs. Using qualitative assessment of the FDG PET image s, all the high-grade STSs (n = 12) were correctly identified, but low-grad e STS (n = 7) could not be differentiated from a benign lesion. Using a qua ntification assessment, there was a 95 per cent sensitivity and a 75 per ce nt specificity in diagnosing STS. Three patients had metastases at presenta tion; two were correctly identified by FDG PET. Conclusion: FDG PET has a role in distinguishing high-grade STS from low-gr ade or benign STS and may have a role in staging malignant tumours.