PT - JOURNAL ARTICLE AU - Garry Ceccon AU - Philipp Lohmann AU - Jan-Michael Werner AU - Caroline Tscherpel AU - Veronika Dunkl AU - Gabriele Stoffels AU - Jurij Rosen AU - Marion Rapp AU - Michael Sabel AU - Ulrich Herrlinger AU - Niklas Schäfer AU - Nadim J. Shah AU - Gereon R. Fink AU - Karl-Josef Langen AU - Norbert Galldiks TI - Early Treatment Response Assessment Using <sup>18</sup>F-FET PET Compared with Contrast-Enhanced MRI in Glioma Patients After Adjuvant Temozolomide Chemotherapy AID - 10.2967/jnumed.120.254243 DP - 2021 Jul 01 TA - Journal of Nuclear Medicine PG - 918--925 VI - 62 IP - 7 4099 - http://jnm.snmjournals.org/content/62/7/918.short 4100 - http://jnm.snmjournals.org/content/62/7/918.full SO - J Nucl Med2021 Jul 01; 62 AB - 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, 20–79 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 &gt; 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.