Dear Health Care Provider,

The FDA is providing information about the potential for increased image artifact associated with Magnetic Resonance Angiography (MRA) imaging for patient follow-up of certain post neurovascular embolization coil procedures.

Neurovascular embolization coils are used in the treatment of brain aneurysms and other vascular abnormalities. These coils are prescription devices implanted by a physician into the aneurysm sac to occlude blood flow and promote thrombosis. As aneurysms treated with coils may have residual filling or may recur, putting the patient at risk for late hemorrhage, follow-up imaging is performed when necessary post procedure. Digital subtraction angiography (DSA) has traditionally been the method used for imaging aneurysms after coiling. However, with advances in MRA image quality and accessibility, many health care providers may choose to use MRA in lieu of DSA because patients are not exposed to ionizing radiation or embolic stroke risks.

Information reviewed by the FDA, including FDA's Medical Device Reports (MDRs), information from device manufacturers, and published literature, indicates that when MRA is performed on patients implanted with neurovascular embolization coils containing 304V stainless steel (either as part of the coil implant itself, or left behind as part of the detachment process), the images may contain larger than expected MR artifact, or image voids when compared to other metals. In these cases, the reduced quality of the MRA image from increased artifact can result in inaccurate clinical diagnoses (e.g., occlusion status) and subsequent inappropriate medical decisions.

Most neurovascular embolization coils currently on the market are labeled as Magnetic Resonance (MR) Conditional. The MR Conditional information in the product labeling conveys to the user the conditions of safe use of the device when scanned within an MR environment. The product labeling for neurovascular embolization coils does not currently convey the extent of MRA image artifact caused by the device or the MRA imaging parameters that will yield the lowest amount of image artifact if MRA is used for patient follow-up.

RECOMMENDATIONS

The FDA recommends that health care providers:

• Be aware of the presence of 304V stainless steel in the coil system(s) typically used (either as part of the coil implant itself, or left behind as part of the detachment process). If uncertain, the applicable device manufacturer should be contacted for information about the coil, its detachment mechanism, and any specific recommendations regarding the use of MRA with their product.
• Understand that 304V stainless steel-containing embolization coil systems may increase image artifact on MRA exams performed at the time of aneurysm follow-up. In these situations, X-ray based DSA should be considered.
• If choosing to use MRA for follow-up, utilize optimal imaging parameters to minimize image artifact, including:
  • Shortest echo times
  • High readout bandwidth
  In addition, ensure that the MRI system at your site meets all conditions provided in the MRI conditional labeling of the coil system (e.g., magnetic field strength in units of Tesla).
• Report any event of image artifact associated with MRA that might have led to misinterpretation of the image to MedWatch's (FDA Safety Information and Adverse Event Reporting program) Online Voluntary Reporting Form:
  • In your report, please include information on the manufacturer(s), brand(s) of coils used, imaging parameters utilized, and follow-up action taken (e.g., DSA completed, DSA results, and applicable interventions)
• Device manufacturers and user facilities must comply with the applicable Medical Device Reporting (MDR) regulations. Health care personnel employed by facilities that are subject to FDA's user facility reporting requirements should follow the reporting procedures established by their facilities. Prompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices.

FDA ACTIONS

The FDA will continue to monitor this situation and will update this communication if significant new information becomes available.

Included below are additional resources related to the issue:

• Bendel, LP, Shellock FG, Steckel M. (1997). The effect of mechanical deformation on magnetic properties and MRI artifacts of type 304 and type 316L stainless steel. Journal of Magnetic Resonance, 7(6), 1170-1173.
• Thompson BG, Brown RD Jr, Amin-Hanjani S, Broderick JP, Cockroft KM, Connolly ES Jr, Duckwiler GR, Harris CC, Howard VJ, Johnston SC, Meyers PM, Molyneux A, Ogilvy CS, Ringer AJ, Torner J. (2015). On behalf of the American Heart Association Stroke Council, Council on Cardiovascular and Stroke Nursing, and Council on Epidemiology and Prevention. Guidelines for the management of patients with unruptured intracranial aneurysms: a guideline for healthcare professionals from the American Heart Association/ American Stroke Association. Stroke, 46(8), 2360-400.
• FDA's MRI Information for Professionals webpage
• MRI Safety Posters

CONTACT US

If you have questions about this communication, please contact CDRH's Division of Industry and Consumer Education (DICE) at [email protected], 800-638-2041, or 301-796-7100.

Sincerely,
/s/
William Maisel, MD, MPH
Deputy Center Director for Science
Center for Devices and Radiological Health
U.S. Food and Drug Administration