Fluorine-18-fluorodeoxyglucose PET imaging of soft-tissue sarcoma

PET with 18F-fluoro-2-deoxy-D-glucose (FDG) was used to study soft-tissue lesions. The goals of the study were to establish FDG uptake in soft-tissue sarcoma, to determine the sensitivity of this technique, to investigate the correlation between histologic grade and glucose consumption and to determine whether FDG-PET can discriminate between benign and malignant lesions.

PET imaging was performed in 18 patients with soft-tissue sarcoma and 4 patients with a benign soft-tissue lesion. Glucose consumption in the tumors was calculated using Patlak's graphical analysis with an assumption made for the lumped constant. Standardized uptake values also were calculated.

All soft-tissue sarcomas were clearly depicted. The median glucose consumption was 13.0 mumole/100 g/min (range 2.9-41.8 mumole/100 g/min). A correlation was found between glucose metabolism and the histopathologic malignancy grade. Such a correlation was not demonstrated for the standardized uptake values. One benign lesion was also visualized. Benign lesions were not visualized in two patients and in the remaining patient an equivocal scan was obtained. Benign lesions could be distinguished from high-grade malignant lesions but not consistently from lesions with low or intermediate malignancy grades.

PET with FDG is an effective technique to visualize soft-tissue sarcomas. We found a sensitivity of 100%. There is a correlation between glucose metabolic rate and tumor malignancy grade. FDG appears to be unsuitable for discriminating benign lesions from soft-tissue sarcomas with low or intermediate malignancy grades.