Effect of MRI on Breast Tissue Expanders andRecommendations for Safe Use
Andrew A. Marano1, Peter W. Henderson, MD MBA1, Martin R. Prince, MD PhD2, Stephen Dashnaw, ARMRIT2, Christine H. Rohde, MD MPH2.
1Columbia/Cornell, New York, NY, USA, 2Columbia University, New York, NY, USA.
Background: Ferromagnetic port-containing breast tissue expanders are currently labeled MRI unsafe due to reports of complications with these devices during MRI, as well as a lack of insufficient evidence to counter these reports. As a result, the current practice is to indiscriminately avoid MRI in patients with these devices. We have previously shown that the Natrelle 133MV 400 mL breast tissue expander has no detectable increase in temperature, and is affected minimally by torque and translational forces when exposed to 1.5T MRI. In this study, we explore further ex vivo experiments to determine the effect of filling the device with air or saline, and the potential utility of lying prone.
Methods: An Allergan 133MV 400 mL breast tissue expander was evaluated in a 1.5T MRI environment. Torque was determined qualitatively on a 0-4+ scale, comparing empty, saline-filled, and air-filled expanders. Tissue expanders were inflated in 60 mL increments and torque was evaluated until ferromagnetic port rotation became non-palpable. The weight required to prevent angular displacement of tissue expanders was determined for both air and saline-filled expanders by incrementally adding water to a container fixed atop the expander until the weight prevented detectable rotation.
Results: When filled with saline and air, the Natrelle 400 mL expander exhibited incrementally decreasing palpable torque with increasing volume. The volume at which torque was no longer detectable was 240 mL of saline and 360 mL of air. The amount of force required to prevent angular displacement was 870 g for an empty expander and 120 g for a saline-filled 400 mL tissue expander.
Conclusions: Our results indicate that there may be a benefit to filling tissue expanders with saline or, to a lesser extent, air prior to undergoing MRI. Furthermore, less than 1 kg is required to prevent rotation of the tissue expander, indicating that prone positioning may be useful in preventing palpable movement of the device. Thus, MRI can reasonably be considered in patients with breast tissue expanders when appropriate peri-procedural choices have been made so that the benefits of undergoing MRI outweigh the risks.
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