To test two-dimensional cardiac-gated phase-contrast (2DGPC) magnetic resonance (MR) imaging in the evaluation of cerebral arteriovenous malformations (AVMs) and the alterations in flow that accompany embolization therapy. A 2DGPC sequence was used to measure flow velocity in the feeding vessels and corresponding contralateral vessels (CCVs) of seven patients (six men and one woman, 21-55 years of age; mean, 37 years) with cerebral AVMs and in the vessels of four healthy volunteers (all men; mean age, 22 years). In the patients, the flow in the feeding vessels exceeded the flow in the CCVs by a margin far greater than the asymmetry in flow in the volunteers. The mean reduction in flow after embolization was 54.9% +/- 11.1 in embolized feeding vessels (n = 6) and 5.3% +/- 2.8 in nonembolized vessels (n = 3). Postembolization flow enhancement was observed in the CCV (n = 2), which suggests a degree of autoregulatory dysfunction. This technique can be used to evaluate the flow patterns of AVMs and the hemodynamic changes that occur with embolization.