What are the limitations of MR Angiography?
MRA does not image calcium, as does CT angiography. The procedure should be avoided in any patient having a pacemaker, implanted neurostimulator, metallic ear implant, or metallic object within the eye socket. It should also be avoided if there is a bullet fragment or if the patient has a port for delivering insulin or chemotherapy. For patients who are very claustrophobic, adequate nursing staff must be on hand to monitor sedation. The clearness of MRA images does not yet match those obtained by conventional angiography. MRI of small vessels, in particular, may not be adequate for diagnosis and treatment planning. Sometimes it may be difficult to separate images of arteries from veins by MRA.
