title: [Magnetic resonance angiography].
abstract: BACKGROUND
  MR angiography (MRA) is a group of MRI techniques capable of producing projectional images of arteries and veins without the use of ionising radiation or catheters.
  
  
  METHODS
  This review describes two of the main techniques, time-of-flight (TOF) MRA and phase contrast MRA, that provide high signal-intensity vessels due to flow phenomena, and a third main technique, contrast-enhanced MRA, which relies on intravenous injection of contrast media. Contrary to the iodine-containing x-ray contrast media, the contrast media for MRA are not nephrotoxic, making contrast-enhanced MRA a good alternative for patients with reduced renal function. MRA is indicated in several vascular areas, especially head and neck arteries and veins, the large thoracic and abdominal arteries and veins, and the lower extremity arteries.
  
  
  CONCLUSIONS
  For several indications, the sensitivity and specificity of MRA is approaching those of the gold standard, x-ray angiography. There are reasons to believe that most diagnostic angiographic procedures will soon be performed as MRA.
authors.affiliation: Røntgen-Radiumavdelingen, Rikshospitalet, Oslo. h.j.smith@rh.uio.no
authors.forename: H J
authors.initials: HJ
authors.lastname: Smith
mesh_terms: D001027:Aortography; D001161:Arteriosclerosis / Q000175:diagnosis; D002533:Cerebral Angiography; D003287:Contrast Media; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods; D012680:Sensitivity and Specificity; D013895:Thoracic Arteries / Q000000981:diagnostic imaging; D020246:Venous Thrombosis / Q000175:diagnosis
chemical_list: D003287:Contrast Media