Early phase 18F-FET PET may help to differentiate tumor progression from treatment-related changes in glioma patients

This is the authors' abstract. We don't add key points for this paper.

Ziel/Aim: Differentiating tumor progression (TP) from treatment-related changes (TRC) in patients with suspected recurrent glioma is challenging and O -(2- 18 F-fluoroethyl)-L-tyrosine ( 18 F-FET) PET may be used during diagnostic work up [ 1 ]. We investigated whether, in addition to standard 18 F-FET PET from 20–40 min p.i., early-phase 18 F-FET PET from 0–2 min p.i. may help to differentiate TP from TRC [ 2 ]. Methodik/Methods: Eighty patients with glioma (WHO grades 2-4) and suspected TP underwent 18 F-FET PET and were retrospectively analysed. Definitive diagnosis was achieved by histopathology or clinico-radiological follow-up (TP, n=64; TRC, n=16). Standard 18 F-FET PET parameters were evaluated in the summed images from 20-40 min p.i. [ 3 ]. In addition tumor-to-brain ratios (TBR) were calculated in early-phase 18 F-FET PET from 0-2 min p.i. using tumour regions-of-interest (ROI) with varying diameters (16 mm (d16); 10 mm (d10)). Receiver operating characteristic analysis was performed and the diagnostic performance to differentiate TP from TRC was assessed using standard 18 F-FET PET parameters, early-phase 18 F-FET PET parameters or combinations thereof. Ergebnisse/Results: Standard 18 F-FET PET parameters based on summed images from 20-40 min p.i. differentiated TP from TRC with a sensitivity, specificity and accuracy of 63%, 75% and 65%, respectively. Early-phase 18 F-FET PET from 0-2 min p.i. yielded a lower diagnostic performance for both ROIs (d16 ROI: sensitivity, 47%; specificity, 94%; accuracy, 56%; d10 ROI: sensitivity, 42%, specificity, 94%; accuracy, 53%). The combination of standard and early-phase 18 F-FET PET increased diagnostic accuracy to differentiate TP from TRC (d16 ROI: sensitivity, 75%, specificity, 75%; accuracy, 75%; d10 ROI: sensitivity, 72%; specificity, 75%; accuracy, 73%). Schlussfolgerungen/Conclusions: The combination of early-phase and standard 18 F-FET PET may help to differentiate TP from TRC in patients with gliomas. Publication History Article published online: 12 March 2025 © 2025. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany