CT Angiography and Magnetic Resonance Angiography
MRA and CTA are considered noninvasive imaging methods to visualize arterial and venous structures with out the need for direct placement of a catheter into a patient’s vessel of interest. The benefit to the patient is that CTA and MRA may be no more uncomfortable than placement of an IV needle into the arm with the subsequent injection of a peripheral arm vein. MRA and CTA are less expensive than the alternative traditional Xray contrast angiographic study and without the risks of needle placement into a groin vessel with subsequent threading of a catheter into the vessel of interest. MRA, as opposed to CTA and traditional angiography, does not require iodine based contrast agents and is safe for patients with renal insufficiency.
Candidates for these procedures are typically patients with increased risk for intracranial aneurysm, arterial narrowing of vessels of the neck, vascular occlusive disease of the lower extremities, or suspected renal arterial narrowing in patients with uncontrolled hypertension. There are also applications in patients with abdominal aortic aneurysm and dissection of the aorta.
MRA and CTA do not replace traditional angiography in every patient as there is still slightly better detail shown on the latter invasive procedure. In some patients there will be findings that require further evaluation by the traditional angiographic exam. The potential advantage of the traditional angiographic exam is that it may allow intravascular treatment of the demonstrated anatomic abnormalities during the same procedure. Many patients will have the MRA and CTA as a screening exam and if results are normal may not need to undergo the traditional angiographic study with its associated discomfort, risks, and relatively high cost.