22 oral: FDG-PET Guided IMRT for Patients with Cervical Cancer

Abstract

sessed a possible additional value of Ga-68-DOTATOC PET/CT for this aim. Materials: Prior to RT, 48 pat. (31f, 17m, 21-79 y) with 54 scull base (SB) meningiomas were studied by both MRI and Ga-68-DOTATOC PET/CT. 34 of them were pretreated by surgery and/or RT. PET/CT data were acquired using the Biograph 16 scanner (Siemens) and fused with MRI using Brain SCAN 5.1 workstation. The GTV were defined first using CT and MRI data (GTVMRI/CT), and then based on PET data (GTVPET). The overlapping regions of GTVMRI/CT and GTVPET resulted in the GTVcommon, which was enlarged to the GTVfinal by addition of volumes definable in only one of the complementing modalities. The contribution of conventional imaging modalities (MRI, CT) and Ga-68-DOTATOC PET to the GTVfinal was evaluated. Results: 48 of 54 SB menigiomas in 45 patients showed DOTATOC uptake and were further analyzed. The addition of Ga-68-DOTATOC PET resulted in modification GTV in 32/54 meningiomas. The acquisition of PET data on a PET/CT scanner allowed detection of osseous infiltration. There were also intratumoral areas (as identified in CT+MRI) showing no SR-expression (38% of mean GTVfinal). The mean additional GTV, obtained as result of PET, was 9 % of the mean GTVfinal. Conclusions: Ga-68-DOTATOC PET delivers additional information to both CT and MRI, representing a promising method for planning the stereotactic RT in scull base meningiomas. Further studies with histological verification of the PET data are necessary to estimate the sensitivity and specificity of the Ga-68-DOTATOC uptake.