Are Nitinol Stents Safe for MRI?

Nitinol stents are generally considered safe for patients to undergo MRI (magnetic resonance imaging) scans after placement. However, there are some important considerations:

Nitinol is non-ferromagnetic, meaning it will not be attracted to the strong magnetic fields of an MRI machine like some other metals. This reduces risks.

However, nitinol stents can still cause image artifacts that distort the MRI pictures in the area around the stent. This needs to be taken into account when interpreting scans.

Heating is a theoretical concern, as the rapidly changing electromagnetic fields of MRI could cause nitinol temperatures to rise very slightly. However studies have not shown significant clinical heating.

Movement or dislodgment of the stent during scanning is highly unlikely given how firmly nitinol adheres to tissues once implanted.

Still, out of an abundance of caution, non-urgent MRI scans are typically only recommended ≥4-6 weeks after bare-metal stent placement to ensure adequate healing/endothelialization first.

Drug-eluting stents may pose a higher theoretical risk than bare-metal due to coating ingredients, so non-urgent MRI is usually delayed up to a year after DES placement when possible.

So in summary - while not 100% risk-free, nitinol stents are generally viewed as safe for MRI when clinically necessary, especially once adequately incorporated in the vessel wall. However, artifacts and safety profiles of recent stents need considering.