Safety of intrauterine devices in MRI.

Simon Bussmann,Andreas Gutzeit,Roger Luechinger,Carolin Reischauer,Dow Mu Koh,Constantin Von Weymarn,Johannes M Froehlich,Peter Lundberg

doi:10.1371/journal.pone.0204220

Abstract

ObjectivesThe paucity of safety information on intrauterine devices (IUD) for magnetic resonance imaging (MRI) examinations is clinically relevant. The aim of this study is to evaluate the MRI safety of clinically used IUDs composed of copper/gold and stainless steel at 1.5T and 3.0T.Materials and methodsWe assessed and compared the displacement force, torque effects, presence of imaging artifacts and heating of IUDs composed of copper/gold (western IUDs) and stainless steel (China) on 1.5 and 3.0T MRI systems.ResultsGold/Copper IUDs can show small deflection angles of 7° ± 7° in the worst-case field gradient of 40T/m (equivalent to magnetic force of 0.5 mN), while the stainless steel IUD experienced significant magnetic force and deflection (Force > 7.5 N; deflection angle 90° ± 1°). Manual rotation and suspension method show no torque effects on gold/copper IUDs but high torque effects were observed by manual rotation on the stainless steel IUD. Heating measurements showed a temperature increase (rescaled to a wbSAR of 4 W/kg) of 1.4°C at 1.5T / 3.4°C at 3.0 T (stainless steel IUD), 3.2°C at 1.5 T / 3.8°C at 3 T (copper/gold IUD), 3.3°C at 1.5 T / 4.8°C at 3 T (copper 1), 3.8°C at 1.5 T / 4.8°C at 3 T (copper 2). The visible imaging artifacts of the copper and gold IUDs at 3 T MRI reach a diameter of 4 mm ± 1 mm, while the stainless steel IUD resulted in artifacts measuring 200mm ± 10 mm when using gradient echo pulse sequences.ConclusionsStandard IUDs (copper/gold) can be considered as conditional for MR safety at 1.5 T and 3.0 T, demonstrating at wbSAR up to 4W/kg and a magnetic field gradient of up to 40T/m with minimal imaging artifacts. The stainless steel IUD, however, induces unacceptable artifacts and is potentially harmful to patients during MRI due to high magnetic dislocation forces and torque (MR unsafe).

Highlights

With the rising global population in recent decades, effective contraceptive methods which are safe, reliable and cheap are needed for family planning [1]
Manual rotation and suspension method show no torque effects on gold/copper intrauterine device (IUD) but high torque effects were observed by manual rotation on the stainless steel IUD
The visible imaging artifacts of the copper and gold IUDs at 3 T magnetic resonance imaging (MRI) reach a diameter of 4 mm ± 1 mm, while the stainless steel IUD resulted in artifacts measuring 200mm ± 10 mm when using gradient echo pulse sequences

Summary

Introduction

With the rising global population in recent decades, effective contraceptive methods which are safe, reliable and cheap are needed for family planning [1]. The intrauterine device (IUD), a contraceptive method that is locally deployed into the uterine cavity, has been shown to effectively prevent pregnancies [references?]. As IUDs are clinically effective and their effects reversible by removal, many women choose IUD to prevent pregnancies. In Asia, especially in China, recent estimates show that 44% of all Chinese women between 15–45 years of age use IUDs. Until recently, there was a mandatory one-child policy in China, and the deployment of IUDs are particular significant. Many different types of IUDs have been in use in China [4]. One product that was widely used in the 1980’s (more than 90% of all IUDs used in China at that time) is made of stainless steel, and known as the “Chinese ring” [4]. There is only one international publication, which describes this ring from a radiological point of view [6]

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