Objective: To evaluate positron emission tomography (PET) using 2-fluoro-2-deoxy-D-glucose (FDG) for clinical application in soft tissue sarcomas.
Summary and background data: FDG PET is a promising noninvasive method for the preoperative assessment of soft tissue sarcomas and may complement radiologic tomography.
Methods: Data from 50 consecutive patients with 59 masses, either suspicious for primary or locally recurrent soft tissue sarcoma, were prospectively gathered. The semiquantitative FDG uptake (standardized uptake values [SUVs]) was calculated in tumor and normal tissue (muscle). Histopathology of surgical specimens and follow-up data were used as control criteria.
Results: In primary soft tissue sarcomas, PET displayed a sensitivity of 91% and a specificity of 88%. Local recurrence was detected with a sensitivity of 88% and a specificity of 92%. All intermediate-grade and high-grade soft tissue sarcomas (primary and locally recurrent) were visualized with a precise differentiation from muscle. Fifty percent of the low-grade sarcomas showed an FDG uptake equivalent to muscle (false-negative results in one primary and three recurrent soft tissue sarcomas). Benign soft tissue tumors (e.g., lipoma, leiomyoma, ganglion) did not accumulate FDG. Inflammation resulted in an increased FDG uptake. The semiquantitative FDG uptake (SUVs) correlated with tumor grade but not with size and histologic type.
Conclusion: High-grade and intermediate-grade soft tissue sarcomas are amenable to PET imaging, whereas low-grade lesions may not be depicted. SUVs for FDG correlate with tumor grade in soft tissue sarcomas. Benign soft tissue tumors are differentiated from higher-grade soft tissue sarcomas. These data show that FDG-PET can complement preoperative radiologic assessment for soft tissue sarcomas and that FDG-PET is a powerful diagnostic tool for detecting high-grade and intermediate-grade local recurrence.