MRI said safe for use with contraceptive devices
New research indicates that use of magnetic resonance imaging (MRI) is safe for use in women who rely on such contraceptive methods as intrauterine devices (IUDs) and implants, as well as in women who have tubal microimplants inserted during hysteroscopic sterilization.1
This review provides reassurance for women using contraceptive devices and clinicians regarding the safety of MRI, says Andrew Kaunitz, MD, professor and associate chair in the Obstetrics and Gynecology Department at the University of Florida College of Medicine — Jacksonville.
As the use of IUDs, subdermal implants, and hysteroscopic sterilization with tubal microimplants continues to increase, addressing the safety of these contraceptive devices when women undergo MRI is relevant, Kaunitz observes. Potential safety concerns during MRI relate to the potential for the intense magnetic field associated with this imaging approach to cause devices to move or become overheated.
To perform the current analysis, Portuguese authors reviewed reports published between 1985 and 2010 that assessed use of MRI in women using contraceptive devices. What prompted the research team's investigation of this subject? "In my hospital, I noticed a woman with a copper intrauterine device that went to consultation with a gynecological ultrasound, which showed that the IUD was embedded in the myometrium thickness," notes the paper's lead author, Lúcia Correia, MD, a physician at the Maternidade Dr. Alfredo da Costa Hospital in Lisbon, Portugal.
The woman had undergone a magnetic resonance imaging procedure, Correia says. From this case, and to understand whether it was a coincidence or if there was a cause-effect relationship, her scientific team began a literature review and published its findings, she states.
In 2005, the American Society for Testing and Materials (ASTM) developed the following three categories to classify MRI use in medical decides:
• MR Safe: devices presenting no risks in all MR environments. This group includes devices made of nonconductive and nonmagnetic elements, such as plastic, silicone, or glass devices.
• MR Conditional: devices presenting no risks in magnetic resonance-specific environments, under specific use conditions. Field conditions that define the MR environment characterization include static magnetic field strength, spatial gradient, time rate of change of the magnetic field, radiofrequency fields, and specific absorption rate.
• MR Unsafe: devices presenting risks in all magnetic resonance environments. Performing MRIs in these cases is contraindicated. This group includes all electromagnetic devices.2
Due to its polyethylene structure, the levonorgestrel intrauterine device (Bayer HealthCare Pharmaceuticals, Wayne, NJ) is included in the group of MR Safe devices, according to the ASTM. Its use does not pose any risk to women in case MRI is performed, the new analysis states.1
Even though copper is not ferromagnetic, there have been some concerns regarding use of MRI on women using a copper IUD (ParaGard CU-IUD, Teva Women's Health, Sellersville, PA). The presence of a device including a metal component in a patient submitted to MRI can lead to injuries deriving from its movement/deflection or from an increase in the device's temperature, the authors of the current paper note. In the case of the copper IUD, this movement/deflection could result in injuries to the endometrium, as well as lead to the possibility of generating image artifacts that would compromise the MRI's diagnostic capability.3
The current analysis found four reports, none of which identified device movement or clinically important overheating associated with MRI and copper IUDs, says Kaunitz. The authors conclude that the copper IUD is rated as MR Conditional.4-7
Although not noted by the authors of this review, the plastic frames of the copper and levonorgestrel IUDs contain the metallic element barium to make them radiopaque with conventional X-rays, notes Kaunitz. Barium presents no safety concerns with MRI, states Kaunitz.
Can MRI be safely used in women with the contraceptive implant Implanon (Merck & Co., Whitehouse Station, NJ)? According to the current paper, the absence of metallic elements and the plastic composition of the implant both justify its classification as an MR Safe device, meaning that under no circumstances will its use pose a risk for women submitted to an MRI.
When it is not possible to clinically identify the location of an Implanon implant, the MRI is considered a second-line diagnostic examination after soft tissue ultrasound, the authors note.
Kaunitz notes the study authors did not consider Nexplanon, the second generation implant. In contrast to Implanon, which is not radio-opaque and contains no barium, Nexplanon includes barium, which makes it radio-opaque. "Although high resolution ultrasound or MRI may be needed to image nonpalpable Implanon implants, Nexplanon implants should be visible with conventional X-rays," says Kaunitz. "This is why barium was added to Nexplanon."
Tubal microimplants used for hysteroscopic sterilization (Essure, Conceptus, San Carlos, CA) contain stainless steel, nickel, and titanium. Two published reports did not identify clinically important microimplant movement or heating associated with magnetic resonance,3,8 Kaunitz notes.
"Published studies on the application of MRI on women using Cu-IUD and Essure have all concluded that it is a safe procedure, provided that the MRI is of a maximum of 3.0 Tesla; thus, Cu-IUD and Essure are classified as MR Conditional," authors of the current paper state. "The only identified effect was a slight increase in the temperature of the device and its surroundings — in vivo, these effects were shown to be nonsignificant."
References
- Correia L, Ramos AB, Machado AI, et al. Magnetic resonance imaging and gynecological devices. Contraception 2012; 85(6):538-543.
- Shellock FG, Woods TO, Crues III JV. MR labeling information for implants and devices: explanation of terminology. Radiology 2009; 253:26-30.
- Shellock FG. New metallic implant used for permanent contraception in women: evaluation of MR safety. Am J Roentgenol 2002;178:1,513-1,516.
- Mark AS. Hricak H. Intrauterine contraceptive devices: MR imaging. Radiology 1987; 162:311-314.
- Hess T, Stepanow B, Knopp MV. Magnetic resonance imaging. Safety of intrauterine contraceptive devices during MR imaging. Eur Radiol 1996; 6:66-68.
- Pasquale SA, Russer TJ, Foldesy R, et al. Lack of interaction between magnetic resonance imaging and the copper-T380A IUD. Contraception 1997; 55:169-173.
- Zieman M, Kanal E. Copper T 380A IUD and magnetic resonance imaging. Contraception 2007; 75:93-95.
- Shellock FG. Biomedical implants and devices: assessment of magnetic field interactions with a 3.0-tesla MR system. J Magn Reson Imaging 2002; 16:721-732.
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