MAGNETIC RESONANCE ANGIOGRAPHY (MRA)
By Brad A. Paulson, MD
Magnetic resonance angiography (MRA) has vastly improved in recent years due to new imaging techniques and contrast. It is now possible to study major arteries with great detail, and we are currently able to see second and third order pulmonary artery branches. In addition to the major arteries of the body, it is possible to study the peripheral arteries of the legs and calves with great detail. Resolution is comparable to digital subtraction angiography.
Patients with suspected renal artery stenosis are ideal candidates for MRA studies. High resolution images are obtained of the renal arteries. Patients with post prandial pain and possible mesenteric ischemia are also ideal to study with MRA.
MRA requires 30 - 60 minutes of imaging time to perform. MR contrast used is non-nephrotoxic and can safely be used in patients with renal insufficiency. The MR contrast is given as a venous injection. Timing is such that the arteries of interest enhance with the contrast, and a 3-D volume is obtained, which can later be evaluated on a workstation in any plane.
In addition to arterial studies, many venous applications exist, including evaluation of the portal vein, IVC, and studies for DVT.
In summary, MRA is an excellent non-invasive method to evaluate the thoracic aorta, pulmonary arteries, abdominal aorta and its branches (renal and mesenteric arteries), and the runoff vessels of the legs. Neuro application are, of course, possible and include carotid arteries and cerebral vasculature. Typically two or three sets of images are obtained and the venous applications are also easily obtainable.
