Current Status of Magnetic Resonance Angiography

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The principles and clinical applications of the different magnetic resonance angiography (MRA) techniques that are available in clinical settings are described in this paper. Time-of-flight (TOF) MRA is the most common MRA method, performed without the intravenous injection of any contrast material. The high diagnostic accuracy of brain threedimensional TOF MRA in the detection of both steno-occlusive lesions and aneurysms is wellknown. Therefore, MRA is usually performed first in suspected cases of these vascular lesions, with subsequent computed tomography angiography (CTA) or conventional angiography for further examination. Phase-contrast MRA is another magnetic resonance technique that allows for the evaluation of flow directions and flow velocities, which is a specific advantage of MRA as compared with CTA. In peripheral arteries, fresh blood imaging (FBI) or contrast-enhanced MRA is preferable because two-dimensional TOF MRA requires a long acquisition time. FBI is a novel and noninvasive MRA technique. However, this technique has been introduced relatively recently and is not available in many current magnetic resonance systems.