Use of FET PET in glioblastoma patients undergoing neurooncological treatment including tumour-treating fields: initial experience
We present our first clinical experience with O-(2-18F-fluoroethyl)-l-tyrosine (FET) PET in patients with high-grade glioma treated with various neurooncological therapies including tumour-treating fields (TTFields) for the differentiation of tumour progression from treatment-related changes.
We retrospectively assessed 12 patients (mean age 51 ± 12 years, range 33–72 years) with high-grade glioma (11 glioblastomas, 1 gliosarcoma) in whom the treatment regimen included TTFields and who had undergone FET PET scans for differentiation of tumour progression from treatment-related changes. Mean and maximum tumour-to-brain ratios (TBRmean, TBRmax) were calculated. The definitive diagnosis (tumour progression or posttherapeutic changes) was confirmed either by histopathology (4 of 12 patients) or on clinical follow-up.
In all nine patients with confirmed tumour progression, the corresponding FET PET showed increased uptake (TBRmax 3.5 ± 0.6, TBRmean 2.7 ± 0.7). In one of these nine patients, FET PET was consistent with treatment-related changes, whereas standard MRI showed a newly diagnosed contrast-enhancing lesion. In two patients treated solely with TTFields without any other concurrent neurooncological therapy, serial FET PET revealed a decrease in metabolic activity over a follow-up of 6 months or no FET uptake without any signs of tumour progression or residual tumour on conventional MRI.
FET PET may add valuable information in monitoring therapy in individual patients with high-grade glioma undergoing neurooncological treatment including TTFields.
KeywordsTTFields Amino acid PET Glioma Treatment-related changes Tumour progression
This work was supported by the Wilhelm-Sander Stiftung, Germany (grant number 2016.069.1).
Compliance with ethical standards
Conflicts of interest
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the principles of the1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Informed written consent was obtained from all individual participants included in the study.