@article {Ceccon918, author = {Garry Ceccon and Philipp Lohmann and Jan-Michael Werner and Caroline Tscherpel and Veronika Dunkl and Gabriele Stoffels and Jurij Rosen and Marion Rapp and Michael Sabel and Ulrich Herrlinger and Niklas Sch{\"a}fer and Nadim J. Shah and Gereon R. Fink and Karl-Josef Langen and Norbert Galldiks}, title = {Early Treatment Response Assessment Using 18F-FET PET Compared with Contrast-Enhanced MRI in Glioma Patients After Adjuvant Temozolomide Chemotherapy}, volume = {62}, number = {7}, pages = {918--925}, year = {2021}, doi = {10.2967/jnumed.120.254243}, publisher = {Society of Nuclear Medicine}, abstract = {The goal of this study was to compare the value of contrast-enhanced MRI and O-(2-[18F]fluoroethyl)-l-tyrosine (18F-FET) PET for response assessment in glioma patients after adjuvant temozolomide chemotherapy (TMZ). Methods: After biopsy or resection and completion of radiotherapy with concomitant TMZ, 41 newly diagnosed and histomolecularly characterized glioma patients (glioblastoma, 90\%; age range, 20{\textendash}79 y) were subsequently treated with adjuvant TMZ. MR and 18F-FET PET imaging were performed at baseline and after the second cycle of adjuvant TMZ. We obtained 18F-FET metabolic tumor volumes (MTVs) as well as mean and maximum tumor-to-brain ratios (TBRmean and TBRmax, respectively). Threshold values of 18F-FET PET parameters to predict outcome were established by receiver-operating-characteristic analyses using a median progression-free survival (PFS) of >= 9 mo and overall survival (OS) of >= 15 mo as reference. MRI response assessment was based on the Response Assessment in Neuro-Oncology (RANO) working group criteria. The predictive value of changes of 18F-FET PET and MRI parameters on survival was evaluated subsequently using univariate and multivariate survival estimates. Results: After 2 cycles of adjuvant TMZ chemotherapy, a treatment-induced reduction of MTV and TBRmax predicted a significantly longer PFS and OS (both P <= 0.03; univariate survival analyses) whereas RANO criteria were not significant (P \> 0.05). Multivariate survival analysis revealed that TBRmax changes predicted a prolonged PFS (P = 0.012) and changes of MTV a prolonged OS (P = 0.005) independent of O6-methylguanine-DNA-methyltransferase promoter methylation and other strong prognostic factors. Conclusion: Changes of 18F-FET PET parameters appear to be helpful for identifying responders to adjuvant TMZ early after treatment initiation.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/62/7/918}, eprint = {https://jnm.snmjournals.org/content/62/7/918.full.pdf}, journal = {Journal of Nuclear Medicine} }