Making RF coils MR-invisible by additive manufacturing using magnetically filled polymer.

PURPOSE: Short-T2 MRI is sensitive not only to targeted tissues but also to signals from materials in RF coils, which can lead to image background artifacts. Current solutions to this problem either compromise imaging performance or impose restrictions on coil design. The goal of the present work is to make RF coils MR-invisible without such drawbacks. METHODS: Effective spoiling of unwanted signals from the housing of RF coils is achieved by filling the material used to construct the housing with magnetic particles. This concept is demonstrated by creating coil formers through additive manufacturing with custom filaments made from magnetite-filled polymer. RESULTS: Unwanted signals from the RF coil are effectively eliminated by using coil formers made from magnetically filled polymer. In this fashion, background-free short-T2 imaging is enabled. CONCLUSION: Making RF coils MR-invisible by using magnetically filled materials simplifies coil design and manufacturing and renders the alteration of MR sequences unnecessary, thereby improving the performance of MRI of tissues with short T2s.