The FDA sent a letter to health care providers warning of the potential for increased image voids when using magnetic resonance angiography (MRA) imaging for follow-up of certain post neurovascular embolization coil procedures.
Because aneurysms treated with coils may have residual filling or may recur, patients are at risk for late hemorrhage, so follow-up imaging is performed as needed.
When MRA is performed on patients implanted with neurovascular embolization coils containing 304V stainless steel — either as part of the coil implant, 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, the agency said
The reduced quality of the MRA images in these cases can result in inaccurate clinical diagnoses and inappropriate medical decisions.
Digital subtraction angiography (DSA) has traditionally been used for imaging aneurysms after coiling, but as MRA image quality and accessibility improve, more health care providers are choosing to use MRA imaging, the agency noted.
The FDA is “not asking manufacturers to phase out the non-MR conditional products,” FDA spokesperson Stephanie Caccomo told FDAnews.
However, the agency recommends that health care providers “be aware of the presence of 304V stainless steel in the coil system(s).” If they are uncertain about a particular coil system, they should contact the device manufacturer for specific recommendations regarding the use of MRA with their product.
If the implanted coil system contains 304V stainless steel, health providers should consider using an X-ray-based DSA instead of an MRA, the agency said.
If health care providers use devices without any labeled information about their safety in the MR environment, said Caccomo, the devices “should be assumed to be MR unsafe.” The FDA did not disclose which devices contain 304V stainless steel because “materials used by manufacturers are considered proprietary information,” she said.
When choosing to use MRA for follow-up, providers should use imaging parameters including a high readout bandwidth and the shortest possible echo times to minimize image artifact, and they should be certain that the MRI system meets all conditions provided in the MRI conditional labeling of the coil system (e.g., magnetic field strength in units of Tesla).”
The agency urged providers to report any image artifacts via the Medwatch online reporting form, including the manufacturer, the brand of coil, the imaging parameters used and any follow-up action taken. — Donna Scaramastra Gorman