[Biologic characterization of soft tissue sarcomes by positron emission tomography (initial results)]

Positron emission tomography (PET) with fluorine-18-fluorodeoxyglucose (FDG), carbon-11-labeled aminoisobutyric acid (AIB) and oxygen-15-labeled water (15O-labeled water) was evaluated for imaging soft tissue sarcomas (STS). Eleven pathologically confirmed STS were evaluated by PET using FDG, AIB and 15O-labeled water. All radiotracers showed an increased activity in viable tumor with a significant differentiation from normal tissue (muscle). An increased glucose metabolism in STS allowed a differentiation from normal tissue (muscle) with FDG. Furthermore, STS showed an increased AIB activity suggesting an increased "A-type" aminoacid transport. AIB therefore can be used for evaluation of STS. 15O-labeled water demonstrated an increased uptake with an overlap with blood vessel activity. These radiotracers supply information about biological properties of STS. Five patients with suspicious lesions in conventional radiodiagnostic but negative PET scans were free of local recurrence, diagnosed either by surgery or by follow-up. Two patients with PET findings suggesting local failure, ultimately demonstrated local recurrence. The differentiation of local recurrence from benign postoperative tissue alterations is encouraging and requires further evaluation.