Lee JN, et al. - The target of this research was to investigate the effect of initial cortical transit time (CTT) on technetium-99m mercaptoacetyltriglycerine (MAG3) diuretic renogram on the necessity for surgery in children with antenatally detected unilateral hydronephrosis caused by ureteropelvic junction (UPJ) stenosis. Based on the findings, it was discovered that CTT on an initial MAG3 scan could serve as a beneficial predictor of the requirement for surgery in the study cohort.