[Magnetic resonance angiography: fields of exploration, main indications and limitations]

Magnetic resonance angiography (MRA) has become a widely accepted technique with regards to the other available noninvasive techniques in the diagnosis of vascular disease. This paper proposes a review of the different indications of this technique in arterial and venous diseases. Among several MRA pulse sequences, the most frequently used until today consisted of a time-of-flight technique which provided angiograms without any injection of intravascular contrast medium. It required to be performed in a plane perpendicular to the main axis of the vessel to be optimal. New techniques, such as contrast medium bolus-enhanced acquisitions allow examination of vascular segments in a plane parallel to their course (coronal for the aorta and lower limb arteries). An increasing number of clinical applications has raised since the implementation of MRA techniques on MR devices; some of them are widely accepted, whereas some others remain under the scope of extensive validation. With a high level of accuracy in grading carotid artery stenosis, MRA is now routinely used in cerebral arterial occlusive diseases and has in part replaced contrast angiography. MRA of the venous system of the brain plays a major role in the diagnosis and follow up of dural venous thrombosis. Other vascular brain diseases, such as vascular malformations, yet have limited uses. Carotid artery dissections are fairly demonstrated with MRA, which can be used for diagnosis as well as for follow-up. The accuracy of MRA in the diagnosis of venous thrombosis of the cervical/mediastinal veins has been reported as high as 100%. Moreover, MRA allows a precise assessment of collateral vessels in case of complete cervical/mediastinal venous thrombosis.