What is a primary limitation of Magnetic Resonance Angiography (MRA)?

Magnetic Resonance Angiography (MRA) indeed has a primary limitation related to its incompatibility with patients who have cardiac pacemakers. This stems from the fact that the strong magnetic fields generated during an MRI can interfere with the function of the pacemaker, potentially leading to malfunction or inappropriate pacing. As a result, patients with implanted cardiac devices are generally contraindicated for MRI procedures, including MRA, to ensure their safety.

In contrast, while other options identify limitations or considerations in the use of MRA, they do not represent the most significant restriction compared to the absolute risk posed by conducting an MRA on a patient with a pacemaker. For instance, high patient cooperation is important for most imaging modalities but does not hold the same critical safety implication. Additionally, while MRA can sometimes underestimate the degree of stenosis and may have limitations in visualizing venous structures, these issues do not carry the immediate risks associated with incompatible medical devices like pacemakers. Therefore, the incompatibility with cardiac pacemakers stands out as a primary limitation of MRA.