Tumour oxygenation assessed by 18F-fluoromisonidazole PET and polarographic needle electrodes in human soft tissue tumours.

BACKGROUND AND PURPOSE: The aim of the study was to identify hypoxia in human soft tissue sarcomas (STS) by PET scanning using the hypoxia marker 18F]-fluoromisonidazole (18F]FMISO) and invasive oxygen sensitive probes (Eppendorf pO2 Histograph, Germany). MATERIALS AND METHODS: Thirteen patients with tumours suspected to be STS were examined by 18F]FMISO PET scanning, and eleven of these patients completed a set of Eppendorf pO2 Histograph measurements following the scanning. RESULTS AND DISCUSSION: By histopathological diagnosis, seven tumours were shown to be STS and six tumours were benign. Ratios between tumour and muscle radioactivity and time activity curves for tumours and muscle tissue were examined in defined regions of interest. Only two malignant tumours showed 18F]FMISO uptake in higher amounts than muscle tissue over time. Hypoxia was present in both benign and malignant tumours as measured by the oxygen electrode method. CONCLUSIONS: 18F]FMISO PET in our setting seemed not to be feasible for the detection of tumour hypoxia in human soft tissue tumours. Neither did it reflect the extent of hypoxia as determined with the oxygen electrode measurements.