Neurovascular Embolization Coils May Cause Magnetic Imaging Problems: FDA Warns

Federal regulators are warning about potential problems associated with neurovascular embolization coils used to treat aneurysms, which may cause inaccurate magnetic resonance angiography (MRA) imaging and result in a medical misdiagnosis. 

On March 12, the FDA issued a safety alert about the risk of “image artifact” or image voids when MRA is used for patient followups after neurovascular embolization coil procedures. The agency also issued a “Dear Healthcare Provider” letter directly to doctors.

Image artifacts are features that appear on diagnostic imaging, which were not present on the original object that was imaged. Artifacts are often referred to by other terms, such as ghost images. They can be the result of many things, including improper operation of the imager or natural processes of the human body itself.

The FDA warned that use of neurovascular embolization coils containing 304V stainless steel can cause image artifacts, or image voids, which don’t exist, to show up on the final images. This occurs more often with 304V stainless steel coils than with other metals.

Neurovascular embolization coils are used to treat brain aneurysms and other vascular abnormalities. They are medical devices containing stainless steel implanted by a doctor into the aneurysm sac to block blood flow and promote thrombosis.

Aneurysms treated with embolization coils may have residual filling or may recur, putting the patient at risk for late hemorrhage. Thus, followup imaging is often necessary to detect this potential risk.

Typically, digital subtraction angiography (DSA) is the preferred method used for imaging aneurysms after coiling. However, many doctors are using MRA because of advances in MRA image quality and accessibility. MRA reduces patient exposure to ionizing radiation and reduces the risk of embolic stroke.

Despite the benefits of MRA, reduced image quality or voids can occur. The reduced quality of the image can cause inaccurate clinical diagnoses and thus inappropriate medical decisions.

The FDA indicates that doctors should be aware of the presence of 304V stainless steel in the coil system of a patient. If they are uncertain if the coil contains 304V stainless steel, they should contact the manufacturer for information about the coil.

Doctors should also understand that 304V coils may reduce image quality or cause voids, thus x-ray based DSA should be considered for some patients.

Additionally, when using MRA, doctors should attempt to minimize image artifact by using the shortest echo times and high readout bandwidth, the FDA advised.

If a patient or health care professional believes an image artifact or void may have led to the misinterpretation of the image report, misdiagnosis, or to incorrect medical decisions, they should report the incident to the FDA’s MedWatch Adverse Event Reporting Program.