Are double pigtail biliary stents safe for MRI?

Yes, double pigtail biliary stents are generally considered safe for MRI exams. Here are a few key points about using double pigtail biliary stents with MRI:

- Double pigtail biliary stents are primarily made from non-ferromagnetic materials like medical grade plastics or nitinol metal alloy. This means they pose very little risk of being affected by the strong magnetic fields or causing imaging artifacts.

- Nitinol stents contain some nickel which can rarely cause artifacts. However the stents are designed specifically for MRI safety.

- There have been extensive tests on these stents that confirm their MRI safety and compatibility. Heating, migration, or other issues are very unlikely.

- Patients with double pigtail biliary stents can be safely scanned using any MRI field strength. No specific restrictions are required.

- The only exception could be stents that contain certain radiofrequency identification (RFID) tags to allow X-ray visibility. The RF signals can interfere with MRI scanning. These tagged stents are uncommon. 

 - As with any medical implant, the radiologist and technician should be informed about the presence of stents before an MRI exam in case any special precautions are needed.

- Some facilities may request clearance from the stent manufacturer just to verify MRI safety documentation. 

However, this is generally considered a very safe and routine MRI procedure. 

So given all the available safety data, double pigtail biliary stents pose very minimal risk for patients undergoing MRI scans when standard safety guidelines are followed.