[(18)F]Fluoroethyltyrosine- positron emission tomography-guided radiotherapy for high-grade glioma

<p<Abstract</p< <p<Background</p< <p<To compare morphological gross tumor volumes (GTVs), defined as pre- and postoperative gadolinium enhancement on T<sub<1</sub<-weighted magnetic resonance imaging to biological tumor volumes (BTVs), defined by the uptake...
Ausführliche Beschreibung

<p<Abstract</p< <p<Background</p< <p<To compare morphological gross tumor volumes (GTVs), defined as pre- and postoperative gadolinium enhancement on T<sub<1</sub<-weighted magnetic resonance imaging to biological tumor volumes (BTVs), defined by the uptake of <sup<18</sup<F fluoroethyltyrosine (FET) for the radiotherapy planning of high-grade glioma, using a dedicated positron emission tomography (PET)-CT scanner equipped with three triangulation lasers for patient positioning.</p< <p<Methods</p< <p<Nineteen patients with malignant glioma were included into a prospective protocol using FET PET-CT for radiotherapy planning. To be eligible, patients had to present with residual disease after surgery. Planning was performed using the clinical target volume (CTV = GTV ∪ BTV) and planning target volume (PTV = CTV + 20 mm). First, the interrater reliability for BTV delineation was assessed among three observers. Second, the BTV and GTV were quantified and compared. Finally, the geometrical relationships between GTV and BTV were assessed.</p< <p<Results</p< <p<Interrater agreement for BTV delineation was excellent (intraclass correlation coefficient 0.9). Although, BTVs and GTVs were not significantly different (<it<p </it<= 0.9), CTVs (mean 57.8 ± 30.4 cm<sup<3</sup<) were significantly larger than BTVs (mean 42.1 ± 24.4 cm<sup<3</sup<; <it<p </it<< 0.01) or GTVs (mean 38.7 ± 25.7 cm<sup<3</sup<; <it<p </it<< 0.01). In 13 (68%) and 6 (32%) of 19 patients, FET uptake extended ≥ 10 and 20 mm from the margin of the gadolinium enhancement.</p< <p<Conclusion</p< <p<Using FET, the interrater reliability had excellent agreement for BTV delineation. With FET PET-CT planning, the size and geometrical location of GTVs and BTVs differed in a majority of patients.</p< Ausführliche Beschreibung