Magnetic resonance angiography without contrast agents

BackgroundThe use of magnetic resonance imaging (MRI) contrast agents should be minimized in MR angiography.ObjectiveOverview of existing native MRI techniques for MR angiographyMaterial and methodsNative MRI angiography uses the fact that unsaturated flowing blood is hyperintense to static tissue (time-of-flight MRA), that blood flow induces adetectable phase shift (phase contrast MRA), that labeling by selective inversion can dynamically image abolus passage (arterial spin labeling) and that special MRI sequences exist which utilize the contrast properties of blood.ConclusionNative MRI angiography, if properly selected, can reliably delineate vessels such as cerebral arteries and coronary arteries and can provide additional information about the flow dynamics.