Intrauterine contraceptive devices (IUD) may be made from nonmetallic materials (e.g., plastic) or a combination of nonmetallic and metallic materials. Copper is typically the metal used in an IUD, however, stainless steel or other metals may also be utilized. The “Copper T” and “Copper 7” both have a fine copper coil wound around a portion of the IUD. Testing conducted to determine MRI issues for the copper IUDs indicated that these objects are safe for patients in the MR environment using MR systems operating at 1.5-Tesla or less. This includes the Multiload Cu375, the Nova T (containing copper and silver), and the Gyne T IUDs. An artifact may be seen for the metallic component of the IUD, however, the extent of this artifact is relatively small because of the low magnetic susceptibility of copper.
Zieman and Kanal (2007) reported 3-Tesla MRI in vitro test results for the Copper T 380A IUD. No significant deflection, torque, heating or artifact was found. Thus, this IUD is acceptable for patients undergoing MRI at 3-Tesla or less.
Importantly, stainless steel IUDs exist and, to date, these devices have not undergone testing to determine if they are acceptable for patients in association with MR procedures.
The Mirena intrauterine system (IUS) is a hormone-releasing device that contains levonorgestrel to prevent pregnancy. This T-shaped device is made entirely from nonmetallic materials that include polyethylene, barium sulfate (i.e. which makes it radiopaque), and silicone. Therefore, the Mirena is safe for patients undergoing MR procedures using MR systems operating at all static magnetic field strengths.
The Implanon implant (Etonogestrel) is a single-rod, nonmetallic, subdermal device that offers women up to three years of contraceptive protection. This implant is acceptable for patients undergoing MR procedures at all static magnetic field strengths (i.e., it is MR Safe).
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