Safety of intrauterine devices in MRI

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Simon Bussmann, Roger Luechinger,  Johannes M. Froehlich,  Constantin von Weymarn,  Carolin Reischauer,  Dow Mu Koh,  Andreas Gutzeit

LOS One - Journal of Peer Reviewed Science

October 9, 2018

Standard 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).

Excerpts from the Abstract

The 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.

Results

Gold/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.

Introduction

From a radiological point of view, the lack of safety information on a range of IUDs within a MRI magnet field, poses a relevant clinical problem for radiologists and gynecologists. There is an ongoing and sometimes controversial debate concerning whether every IUD is safe to undergo MRI investigation, whether IUD placement must be checked after scanning or whether these devices may be dangerous for women during MRI. For our study we selected the Nova T 380, Mona Lisa Cu375 (identical to Multiload Cu 375), Gold Luna and the Chinese ring IUD for investigation. Hormonal IUDs have not been included in this study, since these do not include any metallic, magnetic, or conductive materials and therefore can even be labeled as MR safe on a scientific rationale.

To our knowledge, there are no prior published studies investigating the safety behavior of these devices including the Chinese ring; nor has there been a previous systematic investigation of the temperature change and degree of movement of these IUDs induced by magnetic fields on 1.5 T and 3.0 T MR systems.

Hence, the aim of this study was to investigate the safety of the most frequently used IUDs during MRI at 1.5 T and 3.0 T. This study hopes to clarify whether radiologists should apply IUD specific precaution measures in clinical practice and whether the IUD placement of copper/gold IUD needs to be re-verified after MRI examination.

Read the Entire Abstract at PLOS One

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PLOS ONE

PLOS ONE is an inclusive journal community working together to advance science for the benefit of society, now and in the future. Founded with the aim of accelerating the pace of scientific advancement and demonstrating its value, we believe all rigorous science needs to be published and discoverable, widely disseminated and freely accessible to all.