he role of interim FDG PET-CT to predict treatment response is still a controversy for the pediatric Non- Hodgkin lymphoma (NHL). In order to evaluate disease status, Deauville Scoring (DS) system is a well-known entity, while total lesion glycolysis (TLG) and metabolic tumor volume (MTV) are new players of semiquantitative assessment. The aim of this study is tocompare the diagnostic and predictive performance of DS, TLG and MTV for pediatric NHL patients. Materials and Methods: PET images of staging, interim and treatment response of pediatric FDG avid NHL patients were evaluated retrospectively. Staging and interim PET-CT studies were evaluated for MTV2.5 and TLG2.5 values with “SUVmax cut-off: 2.5”, as well as DS of interim scans, and assessed for a relation with treatment response status. For interim PET-CT, MTV2.5 and TLG2.5 values “>0” and DS “≥3” are accepted as the residual disease. Sensitivity, specificity, negative predictive values of each parameter were evaluated and a ROC analysis is done. Results: The study group included 45 PET scans of 15 children (F/M: 5/10, mean age:9y (range 5-15) diagnosed as NHL. Median MTV2.5 is 117.1 cm3 (range: 25-2084) and TLG2.5 is 494.8 (range: 76-6242) on staging PET studies. No significant relationship was observed in staging PET studies of TLG2.5 and MTV2.5 values for treatment response prediction. On interim PET scans, median MTV2.5 is 0 cm3 (range: 0-16), TLG2.5 is 0 (range: 0-40) and DS is 1 (range: 0-4). Visual analysis showed 4 positive, 11 negative interim scans in the TLG2.5 and MTV2.5 group, while 6 positive and 9 negative interim scans in the DS group. On treatment response evaluation 3 patients had the residual disease and 12 patients were disease-free. When the treatment response was accepted as the gold standard, sensitivity is 66.7% for all groups, but specificity of TLG2.5 and MTV2.5 is higher than the DS group (83.3% vs 66.7% respectively). Negative predictive value of TLG2.5 and MTV2.5 group is higher than DS (91% vs 88% respectively). ROC analysis showed that AUC of TLG2.5 and MTV2.5 group is higher than DS (0.75 vs 0.67), respectively. Conclusion: The results of this study suggest that MTV2.5 and TLG2.5 values on interim PET-CT scans predict treatment response better than Deauville Score in pediatric patients with NHL.