Neurovascular Embolization Coils May Cause Artifacts on MRA Images


The U.S. Food and Drug Administration (FDA) has issued a letter to healthcare providers warning them that neurovascular embolization coils containing 304V stainless steel may increase image artifact when magnetic resonance angiography imaging is used to image a patient’s aneurysm after coiling.

The implanted coils are used to treat brain aneurysms and vascular abnormalities by occluding blood flow and encouraging thrombosis. Residual filling of the aneurysm may develop or the aneurysm may recur; therefore, postprocedure follow-up imaging is performed when needed to prevent late hemorrhage.

Digital subtraction angiography (DSA) is the traditional imaging method; however, many healthcare providers prefer MRA because it does not expose patients to ionizing radiation or put them at risk for embolic stroke.

After reviewing information, the FDA determined that neurovascular embolization coils containing 304V stainless steel can cause images to contain "larger than expected MR artifact, or image voids when compared to other metals," the FDA explains in the healthcare provider letter. This can lead to inaccurate clinical diagnoses and inappropriate medical decisions.

Most such coils currently on the market are labeled as Magnetic Resonance (MR) Conditional. The MR Conditional information included in product labeling specifies the conditions under which the device can safely be scanned by MR equipment but does not describe the extent of MRA image artifact caused by the coil system or list the MRA imaging parameters that will result in the lowest amount of image artifact.

FDA Recommendations

  1. Be aware of whether commonly used neurovascular coil systems contain 304V stainless steel. If this is unclear, contact the manufacturer for information related to the coil, its detachment mechanism, and whether there are any specific instructions about MRA use with the product.

  2. Know that embolization coil systems containing 304V stainless steel may increase image artifact on follow-up MRA exams and consider using x-ray–based DSA instead.

  3. When using MRA in these situations, minimize image artifact by using optimal imaging parameters, including shortest echo times and high readout bandwidth.

  4. Ensure that the MR imaging system in use complies with all conditions identified in the MRI conditional labeling of the coil system (eg, magnetic field strength in units of Tesla).

  5. The FDA will continue to follow this situation and will release additional information if it becomes available.

Reporting Instructions

  1. If image artifact associated with MRA leads to misinterpretation of the image, submit a report using MedWatch's (FDA's Safety Information and Adverse Event Reporting Program) Online Voluntary Reporting Form.

  2. Include information about the manufacturer or manufacturers, brand(s) of coils used, imaging parameters used, and what, if any, follow-up action was taken (eg, whether DSA was completed; DSA results, if any; and applicable interventions).

  3. Device manufacturers and user facilities must follow applicable Medical Device Reporting regulations, and healthcare personnel employed by such facilities should follow their facility's reporting procedures.

  4. Healthcare professionals and patients should report adverse events or side effects related to the use of neurovascular embolization coils to the FDA's MedWatch Safety Information and Adverse Event Reporting Program online or by requesting the reporting form by telephone at 1-800-332-1088.