%0 Journal Article %A Reema Goel %A Kwaku Domfe %A Alexandra Miller %A Simone Krebs %A Robert Young %A Christian Grommes %A Viviane Tabar %A Mark Dunphy %T Initial experience with 18F-Flouroglutamine PET/CT imaging in brain tumor response assessment %D 2019 %J Journal of Nuclear Medicine %P 327-327 %V 60 %N supplement 1 %X 327Objectives: Reliable assessment of therapeutic response and progression in brain malignancy is challenging for neurooncologists, as current standard neuroradiologic tumor biomarkers, including conventional MRI, FDG PET and FLT PET, have suboptimal diagnostic specificity. Pseudoprogression, an apparent increase in contrast-enhancing tumor volume on post-treatment MRI, is a treatment related change seen in a significant number of glioblastoma patients receiving chemoradiotherapy. This study highlights our initial experience evaluating the efficacy of 18F- Flouroglutamine PET for distinguishing true tumor progression from treatment related changes in human subjects. Methods: 20 patients (Gliomas: 5 high grade astrocytomas, 1 anaplastic oligodendroglioma, 1 anaplastic ependymoma and 9 glioblastoma multiforme ; Non gliomas: 3 brain metastases from lung cancer, 1 brain metastases from breast cancer;) with suspected early pseudoprogression (within 12 weeks after completion of radiochemotherapy in gliomas ;n= 14) or late pseudoprogression (>12 weeks post completion of radiation therapy/chemoradiation including gliomas and metastases ; n=6) and equivocal findings on MRI underwent 18F- Fluoroglutamine PET/CT imaging at 15, 90 and 180 minutes post injection. Qualitative and quantitative evaluation (maximum and peak tumor-to-brain and tumor to blood pool ratios (TBRmax, TBRpeak, TBP max, TBPeak) and ROC curve analysis with AUC >0.8 as the cut off was performed. Reference standard was based on the clinical course, follow-up MR imaging and/or histopathological findings. Results: Overall 18F- Fluoroglutamine PET showed sensitivity of 94% [CI 72.4-99.9%] and specificity of 67% [CI 9.5-99.2%] in differentiating true tumor progression from treatment related changes (TP=16; FP=1;TN=2;FN=1). On ROC curve analysis, SUV max, and TBPmax at 90 and 180 min and TBRpeak at 180 min had AUC >0.8. SUVmax at a threshold of 1.35 had a sensitivity and specificity of 100% and 67% at 90 min and 100% and 86% at 180 min. At 180 min, TBPmax at a threshold of 1.73 had a sensitivity and specificity of 79% and 100% and TBRpeak at a threshold of 3.59 had sensitivity and specificity of 69% and 100% respectively. Conclusions: 18F-Fluoroglutamine PET appears sensitive for diagnosis of early/late progression of brain tumor progression post-treatment. %U