Objective:To explore the value of arterial spin labeling (ASL) in detecting epileptogenic zone (EZ) in children with drug-refractory epilepsy (DRE).Methods:From March 2018 to December 2019, 28 children with DRE were collected prospectively in Peking University First Hospital. Structural MRI, ASL sequence, and PET-CT were performed on 28 DRE children. All children underwent surgical treatment. Intraoperative electrocorticogram findings combined with postoperative MRI results were considered the gold standard for locating EZ. A total of 29 EZ were resected in 28 children. Based on the pathological results, the EZ was divided into focal cortical dysplasia (FCD) Ⅰb and Ⅱa group ( n=12), FCD Ⅱ b group ( n=11) and malformation of cortical dysplasia (MCD) group ( n=6). Structural MRI was observed for finding any abnormal changes that could induce epilepsy and was divided into the normal MRI group ( n=13) and the abnormal MRI group ( n=16). The spatial relationship between abnormal areas in the cerebral blood flow (CBF) map and PET images and the gold standard was observed, and the accurate detection rate of EZ was calculated. The region of interest (ROI) on CBF and PET images was drawn. ROIs were defined as EZ, EZ contralateral zone (EZCZ), EZ adjacent zone (EZAZ), EZAZ contralateral zone (EZAZCZ). The CBF and maximum standardized uptake value (SUV max) were measured, and the asymmetry index (AI) value of EZ and EZAZ of CBF and SUV max was calculated respectively. One-way ANOVA was used to compare the difference among 4 regions and 3 pathological types of CBF, SUV max, and AI. The independent sample t-test was used to compare the difference in AI between normal and abnormal MRI groups. Results:In CBF map, the EZ was accurately localized in 89.7% (26/29) of the lesions, in which 24 EZ had decreased perfusion, and 2 EZ had increased perfusion. Among the 24 EZ with decreased perfusion, the CBF of EZ, EZCZ, EZAZ, and EZAZCZ were significantly different( F=8.79, P<0.001). In PET-CT, the EZ was accurately localized in 93.1% (27/29) of the lesions, in which 25 EZ had decreased metabolism, and 2 EZ had increased metabolism. Among the 25 EZ with decreased metabolism, the SUV max of EZ, EZCZ, EZAZ, and EZAZCZ were significantly different ( F=6.40, P=0.001). The AI value of CBF and SUV max of EZ in the abnormal MRI group were larger than those of the normal MRI group, and the difference was statistically significant ( t=3.34, 3.09, P=0.002 , 0.004). There was no statistical difference in the AI values of CBF and SUV max among FCD Ⅰb and Ⅱa group, FCD Ⅱb group and MCD group ( F=2.05, 1.54, P=0.149, 0.234). Conclusions:ASL technology is accurate in detecting EZ. The changes in perfusion and metabolism of normal structural MRI EZ are greater than abnormal structural MRI EZ. There is no obvious difference in CBF and SUVmax changes in different pathological EZ.