Peripheral MR angiography

Atherosclerotic disease of the lower extremities is a common disorder in we stern society. Its debilitating nature calls for accurate diagnosis and tre atment. The gold standard for diagnosing this disease by depiction of vesse l morphology is X-ray angiography (either conventional or digital subtracti on angiography). However, the invasive nature of this technique and the pos sible harmful effects of iodinated contrast agents have fed to the idea tha t non-invasive MR angiography might be a good alternative for acquiring inf ormation about vessel morphology. Most extensively studied was time-of-flig ht MR angiography. Although first results with this technique were encourag ing, it is now apparent that time-of-flight MR angiography is hampered by t he virtue of which it exists, since blood flow not only generates vessel-to -background contrast, but is also the cause of disturbing artifacts. Howeve r, with the introduction of minimally invasive contrast-enhanced MR angiogr aphy, using gadolinium chelates to reduce the T1 of blood, image quality ha s improved dramatically. Moreover, using contrast-enhanced MR angiography, high-resolution three-dimensional data about the entire peripheral vascular tree can be obtained within several minutes, which might make MR angiograp hy a true competitor of X-ray angiography as a diagnostic tool in the clini cal work-up of a patient with complaints of peripheral atherosclerosis. The purpose of this article is to explain working mechanisms and usefulness of both time-of-flight and contrast-enhanced MR angiography.