Abstract
In glioma patients, the differentiation between tumor progression (TP) and treatment-related changes (TRC) remains challenging. Difficulties in classifying imaging alterations may result in a delay or an unnecessary discontinuation of treatment. Positron emission tomography (PET) using O-(2-[18F]fluoroethyl-)-L-tyrosine (18F-FET) has been shown to be a useful tool for detecting TP and TRC. Methods: We retrospectively evaluated 127 consecutive patients with WHO grade II-IV glioma who underwent 18F-FET PET imaging in order to distinguish between TP and TRC. 18F-FET PET findings were verified by neuropathology (40 patients) or clinico-radiological 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 post injection) were determined. Diagnostic accuracy of 18F-FET PET parameters was evaluated by Receiver-Operating-Characteristic (ROC) analysis and chi-square test. The prognostic value of 18F-FET PET was estimated using the Kaplan-Meier method. Results: TP was diagnosed in 94 patients (74%) and TRC in 33 (26%). For differentiating TP and TRC, ROC analysis yielded an optimal 18F-FET TBRmax cut-off value of 1.95 (sensitivity 70%, specificity 71%, accuracy 70%, AUC 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-wildtype, 67% in IDH-mutant tumors, P < 0.001). 18F-FET PET results correlated with overall survival (P < 0.001). Conclusion: In our neuro-oncology department, diagnostic performance of 18F-FET PET was convincing but slightly inferior to that of previous reports.
- Neurology
- Oncology: Brain
- PET
- 18F-FET PET
- glioma
- pseudoprogression
- treatment-related changes
- tumor progression
- Copyright © 2019 by the Society of Nuclear Medicine and Molecular Imaging, Inc.