PT - JOURNAL ARTICLE AU - Gabriele D. Maurer AU - Daniel P. Brucker AU - Gabriele Stoffels AU - Katharina Filipski AU - Christian P. Filss AU - Felix M. Mottaghy AU - Norbert Galldiks AU - Joachim P. Steinbach AU - Elke Hattingen AU - Karl-Josef Langen TI - <sup>18</sup>F-FET PET Imaging in Differentiating Glioma Progression from Treatment-Related Changes: A Single-Center Experience AID - 10.2967/jnumed.119.234757 DP - 2020 Apr 01 TA - Journal of Nuclear Medicine PG - 505--511 VI - 61 IP - 4 4099 - http://jnm.snmjournals.org/content/61/4/505.short 4100 - http://jnm.snmjournals.org/content/61/4/505.full SO - J Nucl Med2020 Apr 01; 61 AB - In glioma patients, differentiation between tumor progression (TP) and treatment-related changes (TRCs) remains challenging. Difficulties in classifying imaging alterations may result in a delay or an unnecessary discontinuation of treatment. PET using O-(2-18F-fluoroethyl)-l-tyrosine (18F-FET) has been shown to be a useful tool for detecting TP and TRCs. Methods: We retrospectively evaluated 127 consecutive patients with World Health Organization grade II–IV glioma who underwent 18F-FET PET imaging to distinguish between TP and TRCs. 18F-FET PET findings were verified by neuropathology (40 patients) or clinicoradiologic follow-up (87 patients). Maximum tumor-to-brain ratios (TBRmax) of 18F-FET uptake and the slope of the time–activity curves (20–50 min after injection) were determined. The diagnostic accuracy of 18F-FET PET parameters was evaluated by receiver-operating-characteristic analysis and χ2 testing. The prognostic value of 18F-FET PET was estimated using the Kaplan–Meier method. Results: TP was diagnosed in 94 patients (74%) and TRCs in 33 (26%). For differentiating TP from TRCs, receiver-operating-characteristic analysis yielded an optimal 18F-FET TBRmax cutoff of 1.95 (sensitivity, 70%; specificity, 71%; accuracy, 70%; area under the curve, 0.75 ± 0.05). The highest accuracy was achieved by a combination of TBRmax and slope (sensitivity, 86%; specificity, 67%; accuracy, 81%). However, accuracy was poorer when tumors harbored isocitrate dehydrogenase (IDH) mutations (91% in IDH-wild-type tumors, 67% in IDH-mutant tumors, P &lt; 0.001). 18F-FET PET results correlated with overall survival (P &lt; 0.001). Conclusion: In our neurooncology department, the diagnostic performance of 18F-FET PET was convincing but slightly inferior to that of previous reports.