Functional imaging and detection of local recurrence in soft tissue sarcomas by positron emission tomography

Besides anatomically-based radiodiagnostics, functional imaging may be used for characterizing soft tissue sarcomas (STS). This study evaluates positron emission tomography (PET) with three different radiotracers (fluorine-18 deoxyglucose [FDG], carbon-11 aminoisobutyric acid [AIB] and oxygen-15-labeled water [O15-water]) for imaging STS and the detection of local recurrence.

21 patients presented with 9 primary STS, 5 recurrent STS and 10 lesions suspicious for local recurrence (radiological tomography). Standardized uptake values (SUV) were calculated in tumor and normal tissues (muscle/blood vessels). Surgery with pathological examination or follow-up data were referred to as control criteria.

All tracers accumulated in STS with no difference between primary and locally recurrent tumors. The uptake in STS was increased compared to muscle (FDG, P < 0.0001; AIB, P = 0.0039; O15-water, P = 0.002) and to blood vessels for FDG (P < 0.0001) as well as AIB (P = 0.0038). Of 10 patients with suspected recurrence, 6 presented neither PET criteria for recurrence nor local failure in the specimens or during follow-up, while 4 cases with positive PET scans were ultimately diagnosed with local failure.

Besides FDG, AIB and O15-water were shown to accumulate in primary and recurrent STS of different histologic type. A precise differentiation from normal muscle was found for all tracers. FDG and AIB differentiated viable tumor from blood vessels. PET using FDG, AIB and O15-water is suitable for functional imaging of STS and the detection of sarcoma recurrence.