Total Body MRA

Sunday, 29 Sep 2002 14:48:30 GMT

The popularity of MRA is understandable. It provides an accurate depiction of the vascular anatomy over large regions of the body. It produces images of luminal anatomy that can be combined with other MR sequences to show physiological information. It is three-dimensional, enabling the creation of an essentially infinite number of projections of the vascular anatomy, even after the patient has left the MR scanner. More important, it eliminates the risks of ionizing radiation, and gadolinium contrast agents have no clinical nephrotoxicity ^1,2 and are very rarely associated with allergic reactions. ³ Last, MRA is highly accurate. ⁴

There are disadvantages to MRA. Some patients cannot be scanned because of claustrophobia. In older scanners with a long bore, as many as 10% to 20% of patients may experience claustrophobia, but the incidence is greatly reduced in newer scanners with shorter bores. MRA is more expensive than many other noninvasive imaging techniques, though it is certainly much less costly than conventional angiography. Because top-of-the-line scanners are needed for MRA, its availability is limited. And a high level of skill is required to run those scanners, which may also be in short supply in some locations. Finally, there are important contraindications to MRA, including implanted pacemakers, brain aneurysm clips, and orbital metal. ⁵

The opportunity to eliminate ionizing radiation deserves special note. In general, the exposure to ionizing radiation from computed tomographic angiography (CTA) and conventional angiography is within acceptable limits. Nonetheless, a technique that completely eliminates ionizing radiation offers the opportunity to repeat scans over and over, and acquire multiple phases of time-resolved information as the contrast bolus passes through the body. It is also possible to repeat the examination day after day, without worrying about cumulative radiation exposure.

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Total Body MRA