In patients with vein of Galen malformations, high-flow shunting decreases cerebral perfusion. By reducing or eliminating these shunts, transarterial embolization can improve cerebral perfusion and clinical outcomes. Quantifying pre- and postembolization shunt blood flow may help determine the optimal timing and efficacy of embolization and may provide prognostic information. The authors used magnetic resonance imaging noninvasive optimal vessel analysis as a novel modality to measure volumetric blood flow through vein of Galen malformation shunts in a neonate and an infant before and after transarterial embolization.